IS-QZSS Ver. 1.6
Quasi-Zenith Satellite System
Navigation Service
Interface Specification for QZSS
(IS-QZSS)
V1.6
This document is effective until the operational QZSS ground system (established and operated 15 years from 2018 by QuasiZenith Satellite System Services Inc. (QSS)) is completed and the operation of "MICHIBIKI" with the established system
is started (currently, scheduled after Sept. 2016).
After starting the operation of "MICHIBIKI" with new ground system, the signal and service will be supplied depending on
"Performance Standard of Quasi-Zenith Satellite System Services" and "interface Specification of Quasi-Zenith Satellite
System Services".
Japan Aerospace Exploration Agency
November 28, 2014
IS-QZSS Ver. 1.6
Preface
JAXA is pleased to announce the publication of "IS-QZSS Version 1.6" on the data publication website for
Quasi-Zenith Satellite System (QZSS) "MICHIBIKI" ("QZ-vision": URL: qz-vision.jaxa.jp/USE/isqzss/index_e.html) on 28 November 2014. This is a revision notice on the IS-QZSS Version 1.5 previously
released on March 2013. Main items to be updated are following;
(1)
Adding notes on QZSS signals to be modified according to the updating specification of GPS
signals in the future IS-QZSS update.
(2)
Updating information for QZS-1 based on the actual operation after the launch.
(3)
Updating information for L1-SAIF signal.
(4)
Updating information for LEX signal (adding the description of MADOCA-LEX and deleting that
of GSI-LEX (test message of Geographical Survey Institute of JAPAN (GSI)).
JAXA will invite comments on the document from user communities as it was done for previous
publication of IS-QZSS. JAXA always welcomes comments and questions from users as part of our
commitment to continually improve both this IS-QZSS document and the QZSS. If you have any questions
or suggestions for improvements, we would like you to send a mail to the secretariat
(
). We also welcome communication with receiver manufacturers concerning the
design and manufacturing of receivers.
This specification describes the user interface specification of Quasi Zenith Satellite-1 "MICHIBIKI"
operated by "JAXA" until operation by QSS Inc. starts. After starting the operation of "MICHIBIKI" with
new ground system, the signal and service will be provided depending on "Performance Standard of
Quasi-Zenith Satellite System Services" and "Interface Specification of Quasi-Zenith Satellite System
Services.
Disclaimer
(1) IS-QZSS and L-band Positioning Signal transmitted from QZS-1 (hereinafter referred to as "Signals" collectively) is provided
without any warranty including but not limited to accuracy, usefulness, Positioning Signal continuity and fitness for a particular
purpose of use of the Signals.
(2) No liability is assumed for any direct or indirect damages resulting from the use of the Signals, or from any product or service
developed based on the Signals.
IS-QZSS Ver. 1.6
REVISION RECORD
LTR
DESCRIPTION
1.0
Initial release
DATE
17 June 2008
1.1
Adding new message type "No. 20" to LEX signal for the experiment
to be conducted by Geographical Survey Institute.
Adding notes on items to be modified according to the progress of
GPS L1C design.
31July 2009
1.2
Adding notes on QZSS L1C message description to be modified
according to the progress of GPS L1C message design.
Adding the information for L1-SAIF+ message
Adding the information for QZSS Website and Operational
information and Data
Adding notes on items to be modified according to the progress of
developing IMES(Indoor Messaging System)
Typo or editorial correction
25 Feb. 2011
1.3
Adding notes on QZSS L1C message description to be modified
according to the progress of GPS L1C message design.
Adding the information for SPAC-LEX signal
Adding updating information for QZS-1 operating after the
launching
Typo or editorial correction
22 June 2011
1.4
Adding updating information for QZS-1 operating after the
launching
Typo or editorial correction
28 Feb. 2012
1.5
(1) Adding notes on QZSS signals to be modified according to the
updating specification of GPS signals in the future IS-QZSS
update.
(2) Updating information for QZS-1 based on the actual operation
after the launch.
(3) Updating information in the timing of Ephemeris parameters,
Almanacs and UTC parameters update.
(4) Updating information for L1-SAIF signal.
(5) Updating information for LEX signal.
(6) Adding notes on items to be modified according to the progress
of developing IMES (Indoor Messaging System).
(7) Typo or editorial correction.
27 March, 2013
1.6
(1) Updating information for QZS-1 based on the actual operation
after the launch.
(2) Adding notes on QZSS signals to be modified according to the
updating specification of GPS signals in the future IS-QZSS
update.
(3) Updating information for L1-SAIF signal.
(4) Updating information for LEX signal (adding the description of
MADOCA-LEX and deleting that of GSI-LEX (test message of
Geographical Survey Institute of JAPAN (GSI)).
(5) Typo or editorial correction.
28 Nov., 2014
APPROVED
IS-QZSS Ver. 1.6
Table of Contents
1 SCOPE ............................................................................................................................................................. 1
2 APPLICABLE DOCUMENTS ................................................................................................................... 3
3 OVERVIEW OF QZSS ................................................................................................................................ 4
3.1 OVERVIEW OF QZSS ....................................................................................................................... 5
3.1.1 System Overview .................................................................................................................... 5
3.1.2 Operation .............................................................................................................................. 12
3.1.3 Signals transmitted by QZS = QZS Signals ....................................................................... 18
3.1.4 Time System and Coordinate System ................................................................................. 24
3.2 INTERFACE WITH OTHER SYSTEMS ............................................................................................... 25
3.2.1 QZSS Time System Relative to Other GNSS ..................................................................... 25
3.2.2 QZSS Coordinate System Relative to Other GNSS ........................................................... 25
4 QZSS COVERAGE, AVAILABILITY AND PERFORMANCE ...................................................... 27
4.1 QZSS SERVICE AREA .................................................................................................................... 27
4.1.1 Single QZS Coverage Area ................................................................................................... 27
4.1.2 QZSS Coverage Area ............................................................................................................ 28
4.1.3 Elevation Angle Variation for QZSS Constellation ............................................................ 29
4.1.4 QZSS constellation availability ........................................................................................... 30
4.1.5 Target Regions for Ionospheric Parameters Transmitted by QZS .................................... 30
4.1.6 Availability Improvement when QZSS and Galileo are combined with GPS ................... 31
4.2 SERVICE AVAILABILITY.................................................................................................................. 37
4.2.1 The fixed initial right ascension of ascending node depending on the launch time ........ 37
4.3 SYSTEM PERFORMANCE ................................................................................................................ 39
4.3.1 Availability ............................................................................................................................ 39
4.3.2 Alert flag, URA, Health Data and Integrity Data .............................................................. 39
4.3.3 Accuracy ................................................................................................................................ 40
5 QZSS SIGNAL PROPERTIES .............................................................................................................. 42
5.1 QZS POWER LEVELS, BANDWIDTHS AND CENTER FREQUENCIES ................................................ 42
5.1.1 Overview of signal properties .............................................................................................. 43
5.1.2 Navigational messages......................................................................................................... 49
5.2 L1C/A SIGNAL ............................................................................................................................... 53
5.2.1 RF characteristics................................................................................................................. 53
5.2.2 Messages ............................................................................................................................... 53
5.3 L1C SIGNAL .................................................................................................................................. 64
5.3.1 RF Characteristics................................................................................................................ 64
5.3.2 Messages ............................................................................................................................... 65
5.4 L1-SAIF SIGNAL ........................................................................................................................... 82
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5.4.1 RF characteristics................................................................................................................. 82
5.4.2 Error Correction Code .......................................................................................................... 82
5.4.3 Message ................................................................................................................................. 82
5.5 L2C SIGNAL ................................................................................................................................ 106
5.5.1 RF characteristics............................................................................................................... 106
5.5.2 Message ............................................................................................................................... 106
5.6 L5 SIGNAL ................................................................................................................................... 121
5.6.1 RF characteristics............................................................................................................... 121
5.6.2 Message ............................................................................................................................... 121
5.7 LEX SIGNAL................................................................................................................................ 137
5.7.1 RF Signal Characteristics .................................................................................................. 137
5.7.2 LEX Messages..................................................................................................................... 140
6 USER ALGORITHMS ............................................................................................................................. 182
6.1 CONSTANTS................................................................................................................................. 182
6.1.1 Speed of Light ..................................................................................................................... 182
6.1.2 Angular Velocity of the Earth's Rotation .......................................................................... 182
6.1.3 Earth's Gravitational Constant ......................................................................................... 182
6.1.4 Circular Constant ............................................................................................................... 182
6.1.5 Semi-Circle.......................................................................................................................... 182
6.2 USER ALGORITHMS RELATING TO TIME SYSTEMS AND COORDINATE SYSTEMS ............................ 182
6.2.1 User algorithms relating to time systems ........................................................................ 182
6.2.2 User Algorithms relating to Coordinate Systems ............................................................ 183
6.3 COMMON GNSS ALGORITHMS .................................................................................................... 184
6.3.1 Time Relationships ............................................................................................................. 184
6.3.2 User Algorithm for SV Clock Offset .................................................................................. 186
6.3.3 Ionospheric Delay Correction for Dual Frequency Users ................................................ 187
6.3.4 Correction of Inter-Signal Group Delay Error by Users of Only One Signal ................. 190
6.3.5 Calculation of Satellite Orbit using Ephemeris Data ...................................................... 191
6.3.6 Calculation of Satellite Orbit and SV Clock Offset using Almanac Data ....................... 191
6.3.7 Calculation of Coordinated Universal Time (UTC) using the global standard time
parameter..................................................................................................................................... 193
6.3.8 Correction of Ionospheric Delay Using Ionospheric Parameters .................................... 193
6.3.9 Correction Using NMCT (L1C/A Signal) and DC Data (L1C, L2C and L5 Signals) ...... 193
6.3.10 User Algorithms Relating to Interoperability with Other Satellite Navigation Systems
194
6.4 L1 SAIF ALGORITHM.................................................................................................................. 195
6.4.1 Validity period (Time-out period) ...................................................................................... 195
6.4.2 Error Correction Algorithm ............................................................................................... 195
6.4.3 Algorithm for Integrity information .................................................................................. 202
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6.4.4 Calculation of QZSS satellite Position .............................................................................. 204
6.5 LEX ALGORITHM ........................................................................................................................ 205
6.5.1 Reed Solomon Coding/Decoding Algorithm for LEX Navigation Message ..................... 205
6.5.2 Considerations for using Message Type 12 (MADOCA-LEX) ......................................... 208
6.6 OTHER INFORMATION ................................................................................................................. 210
6.6.1 Instrumental Bias in Receivers ......................................................................................... 210
7 PROVISION OF QZSS OPERATIONAL INFORMATION AND DATA VIA THE INTERNET
211
7.1 QZSS WEBSITE FOR OPERATIONAL INFORMATION AND DATA .................................................... 211
7.2 RELEASE OF QZSS INFORMATION AND DATA ............................................................................. 211
7.2.1 NAQU (NOTICE ADVISORY TO QZSS USERS) ............................................................ 212
7.2.2 Experimental Schedule ...................................................................................................... 212
7.2.3 Evaluation result for System Performances ..................................................................... 212
7.2.4 User Operation Support Tool ............................................................................................. 212
7.2.5 Provision of Precise Orbit & Clock for QZSS and GPS .................................................... 213
7.2.6 Detailed Information for Precise Orbit & Clock Estimation for research purposes ...... 213
8 DIFFERENCES WITH GPS .................................................................................................................. 214
8.1 DIFFERENCES IN NAVIGATION MESSAGES .................................................................................. 214
8.1.1 Differences with GPS in terms of L1C/A signal ............................................................... 214
8.1.2 Differences with GPS in terms of CNAV message on L2C and L5 signals ..................... 216
8.1.3 Differences with GPS in terms of CNAV2 message on L1C signals................................ 218
8.2 DIFFERENCE OF RF CHARACTERISTICS ...................................................................................... 220
8.2.1 Difference of Modulated Diffusion Method of Signal ....................................................... 220
8.2.2 Difference of Signal Phase Relation of LIC Signal........................................................... 220
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List of Figures
Figure 3.1.1-1 System overview ............................................................................................. 5
Figure 3.1.1-2 QZSS Orbit and Ground Track Diagram for the Three-Satellite Constellation
.......................................................................................................................................... 6
Figure 3.1.1-3 Constellation Orbit Track Diagram (EPOCH=2009/Dec/26/12:00UTC) for the
Three-Satellite Constellation .......................................................................................... 6
Figure 3.1.1-4 QZS Orbit Ground Tracks ............................................................................... 8
Figure 3.1.1-5 QZS .................................................................................................................. 9
Figure 3.1.1-6 QZS Block Diagram ........................................................................................ 9
Figure 3.1.1-7 Mapping of Ground Stations ........................................................................ 10
Figure 3.1.1-8 MCS ................................................................................................................ 11
Figure 3.1.1-9 TT&C Antenna ............................................................................................... 11
Figure 3.1.2-1 System data flow ........................................................................................... 12
Figure 3.1.2-2 An example of the update timing of the navigation message ..................... 13
Figure 3.1.2-3 An example of uplink timing of the navigation message ............................ 14
Figure 3.1.2-4 Relationship between "Alert" flag and URA/NSC switching ...................... 16
Figure 3.1.2-5 Range of Orbital Maintenance ..................................................................... 17
Figure 3.1.3-1 Power Spectral Density of QZS Signals ....................................................... 18
Figure 3.1.3-2 Examples of relative velocity of signals (Change rate of distance) between
each city and QZS-1 (See Table 3.1.1-1 for calculation condition. Observation EPOCH
= 2009/Dec/26/12:00UTC. Horizontal axis means elapsed time from EPOCH.) ......... 20
Figure 3.1.3-3 Examples of Elevational and Azimuthal angles for each city (See Table
3.1.1-1 for calculation condition. Observation EPOCH = 2009/Dec/26/12:00 UTC) .... 22
Figure 3.1.3-4 Examples of changes of received signal power level for each city (See Table
3.1.1-1 for calculation condition. Observation EPOCH = 2009/Dec/26/ 12:00 UTC.
Horizontal axis means elapsed time from EPOCH.) .................................................... 23
Figure 3.2.1-1 Diagram of Time System Relationships between QZSS, GPS and Galileo 25
Figure 3.2.2-1 Convergence of Geodetic Coordinate Systems ............................................. 26
Figure 4.1.1-1 Percentage of Time during which a Single QZS can be seen at an Elevation
Angle of 10° or more ....................................................................................................... 27
Figure 4.1.1-2 Percentage of Time during which a Single QZS can be seen at an Elevation
Angle of 60° or more ....................................................................................................... 27
Figure 4.1.2-1 Percentage of Time during which at least One QZS in the 3-satellite QZSS
constellation can be seen at an Elevation Angle of 10° or more .................................. 28
Figure 4.1.2-2 Percentage of Time during which at least One QZS in the 3-satellite QZSS
constellation can be seen at an Elevation Angle of 60° or more .................................. 28
Figure 4.1.3-1 Example for Variation of QZSS Constellation (for 3 satellites) Elevation
Angles for eight cities (See Table 3.1.1-1 for calculation condition of QZS-1. It is
assumed that the right ascension of ascending node for QZS-2 and -3 is ± 120 deg from
that value of QZS-1. Observation EPOCH = 2009/Dec/26/12:00UTC Horizontal axis
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IS-QZSS Ver. 1.6
means elapsed time from EPOCH.) .............................................................................. 29
Figure 4.1.4-1 Average Number of QZS Satellites that can be seen at an Elevation Angle of
10° or more with the 3-satellite QZSS Constellation ................................................... 30
Figure 4.1.5-1 Target Regions for Ionospheric Parameters Transmitted by QZS .............. 30
Figure 4.1.6-1 Percentage of Time when PDOP < 6 for an Elevation Angle Mask of 20° and
40° (1/2)........................................................................................................................... 32
Figure 4.1.6-2 Average Number of Visible Satellites for an Elevation Angle Mask of 10°, 20°
and 40° (1/3) ................................................................................................................... 34
Figure 4.2.1-1 Initial Single-satellite QZSS Visibility Time for eight Reference Locations.
(See Table 4.2.1-1 for calculation condition. Dark shaded areas represent elevation
angles of 60[deg] or more; light blue areas represent elevation angles of 10[deg] to
60[deg] and white is less than 10[deg]; vertical scale is hours on UTC and JST.) ...... 38
Figure 4.3.2-1 "Alert" flag, URA, Health Data and Integrity Data Maximum Notification
Time ................................................................................................................................ 40
Figure 5.1.1-1 Phase Relations of LI Signal for QZS-1 and GPS-III
(Counterclockwise
rotation means phase leading of the signal. Each signal phase means relative phase at
modulation bit="0") ........................................................................................................ 44
Figure 5.1.1-2 Phase Noise of all QZS signals ..................................................................... 45
Figure 5.1.1-3 Definition of code jitter σjitter ......................................................................... 46
Figure 5.1.1-4 Definition of delay time, Δ, for PRN code rising/falling edge ...................... 46
Figure 5.1.2-1 QZS URA and Health Data on L1C/A signal ............................................... 49
Figure 5.3.1-1 L1C Signal Structure .................................................................................... 64
Figure 5.3.2-1 Relationship between TOI, ITOW & time of week ...................................... 68
Figure 5.4.2-1 FEC Generation Method ............................................................................... 82
Figure 5.4.3-1 Message Block Format .................................................................................. 83
Figure 5.6.1-1 L5 Signal Structure .....................................................................................121
Figure 5.7.1-1 LEX Signal Structure ..................................................................................137
Figure 5.7.1-2 Block diagram of LEX code generation .......................................................138
Figure 5.7.1-3 Timing Relationship between the LEX Short Code and Long Code ..........139
Figure 5.7.2-1 LEX Message Structure ...............................................................................140
Figure 5.7.2-2 Reed-Solomon Encoding ..............................................................................142
Figure 5.7.2-3 Data Part, Message Type 10 – Signal Health, Ephemeris & SV Clock .....143
Figure 5.7.2-4 Data Part, Message Type 11 – Signal Health, Ephemeris & SV Clock and
Ionospheric Correction ..................................................................................................144
Figure 5.7.2-5 Signal Health Packet Structure ..................................................................146
Figure 5.7.2-6 Ephemeris & SV Clock Packet Content ......................................................149
Figure 5.7.2-7 Ionospheric Correction Packet Content ......................................................156
Figure 5.7.2-8 LEX message structure of Message Type 12...............................................160
Figure 6.4.2-1 Definition of interpolation with four surrounding IGPs ............................199
Figure 6.4.2-2 Definition of interpolation with three surrounding IGPs ..........................200
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Figure 6.5.2-1 The timeline chart of the transmitting sequence for Clock Correction
Messages in RTCM .......................................................................................................208
Figure 6.5.2-2 Example of the generation of "GPS Clock Correction message" (MT=1058)
with Clock Correction information in MADOCA-LEX ................................................209
Figure 6.5.2-3 Example of the generation of "GPS Clock Correction message" (MT=1058)
with dummy data. .........................................................................................................209
List of Tables
Table 3.1.1-1 Calculation condition for QZS-1 nominal orbit ................................................ 8
Table 3.1.1-2 Location of Ground Station ............................................................................ 10
Table 3.1.3-1 General Specifications for QZS Signals ......................................................... 19
Table 3.1.3-2 Doppler coefficients for signals....................................................................... 21
Table 4.2.1-1 QZS-1 Visibility Time for eight reference locations (from 2014/Jan. to
2014/Dec.) ....................................................................................................................... 37
Table 4.3.3-1 Positioning Accuracy by means of Availability Enhancement Signals ......... 41
Table 4.3.3-2 Positioning Accuracy by means of Performance Enhancement Signals ....... 41
Table 5.1-1 QZS signal specifications ................................................................................... 42
Table 5.1.1-1 Configuration of QZS signals ......................................................................... 43
Table 5.1.1-2 Differences in Pseudo Random Noise (PRN) code phases among QZS signals
........................................................................................................................................ 47
Table 5.1.2-1 Details of Health (5-bit health) code for all QZSS signals ............................ 50
Table 5.2.2-1 Content identification using Data ID and Space Vehicle ID ......................... 57
Table 5.2.2-2 GPS page number and the reference of data structure corresponding to the
broadcasted Data-ID and SV-ID .................................................................................... 57
Table 5.2.2-3 Sequence of Satellite Health in the frame when Data-ID="11"(B)................. 59
Table 5.2.2-4 Sequence of NMCT in the frame when Data-ID="11"(B) ................................ 63
Table 5.3.2-1 Definition of Ephemeris parameters and SV clock parameters for
Navigational Message DL1C ........................................................................................... 67
Table 5.3.2-2 Definition of page number and Maximum transmit Intervals for Navigational
Message DL1C .................................................................................................................. 71
Table 5.3.2-3 Definition of UTC parameters and Ionospheric parameters for Navigational
Message DL1C .................................................................................................................. 72
Table 5.3.2-4 Definition of GPS GNSS Time Offset and Earth Orientation Parameters for
Navigational Message DL1C ........................................................................................... 74
Table 5.3.2-5 Definition of Reduced Almanac parameters for Navigational Message DL1C 75
Table 5.3.2-6 Definition of Midi Almanac parameters for Navigational Message DL1C ..... 78
Table 5.3.2-7 Definition of DC data for Navigational Message DL1C .................................. 80
Table 5.4.3-1 SAIF Message Types ....................................................................................... 84
Table 5.4.3-2 Message Type 1: PRN Mask Data .................................................................. 86
Table 5.4.3-3 PRN Slot Assignments to GNSS Satellites .................................................... 87
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Table 5.4.3-4 Message Types 2 ~ 5: Fast Correction ............................................................ 88
Table 5.4.3-5 UDRE value .................................................................................................... 88
Table 5.4.3-6 Message Type 6: Integrity Data ..................................................................... 89
Table 5.4.3-7 Message Type 7: Fast Correction Degradation Factor .................................. 89
Table 5.4.3-8 Message Type 10: Degradation Parameter .................................................... 90
Table 5.4.3-9 Message Type 18 Format: IGP Mask ............................................................. 91
Table 5.4.3-10 Specification of IGP locations ....................................................................... 92
Table 5.4.3-11 Message Type 24 (Fast & Long-term Corrections) ...................................... 96
Table 5.4.3-12 Message Type 25: Long-Term Correction ..................................................... 97
Table 5.4.3-13 Partial message format of Message Type 25 ................................................ 97
Table 5.4.3-14 Information to specify the ephemeris of GLONASS .................................... 98
Table 5.4.3-15 Message Type 26: Ionospheric Delay Correction ......................................... 99
Table 5.4.3-16 GIVEI Value .................................................................................................. 99
Table 5.4.3-17 Message Type 28: Clock – Orbit Covariance ...............................................100
Table 5.4.3-18 Message Type 63 (Null Message) ................................................................100
Table 5.4.3-19 Message Type 12: Timing Information ........................................................101
Table 5.4.3-20 Message Type 52: TGP Mask .......................................................................101
Table 5.4.3-21 Specification of TGP locations (1/2) .............................................................102
Table 5.4.3-22 Message type 53: Zenith Tropospheric Delay Correction ...........................104
Table 5.4.3-23 Message Type 56: Inter Signal Bias Correction Data ................................104
Table 5.4.3-24 QZS Ephemeris Data ...................................................................................105
Table 5.5.2-1 Definitions of message types for Navigational Message DL2C ......................107
Table 5.5.2-2 Maximum Transmit Intervals for Navigational Message DL2C....................108
Table 5.5.2-3 Definition of Ephemeris parameters for Navigational Message DL2C .........109
Table 5.5.2-4 Definition of SV clock parameters for Navigational Message DL2C ............. 111
Table 5.5.2-5 Definition of ionospheric parameters for Navigational Message DL2C ........ 112
Table 5.5.2-6 Group Delay Differential Correction Parameters (TGD, ISC) for Navigational
Message DL2C ................................................................................................................. 113
Table 5.5.2-7 Ephemeris related parameter (WNop) for Navigational Message DL2C ....... 113
Table 5.5.2-8 Definition of Midi Almanac parameters for Navigational Message DL2C .... 114
Table 5.5.2-9 Definition of Reduced Almanac parameters for Navigational Message DL2C
....................................................................................................................................... 115
Table 5.5.2-10 Definition of parameters for DC data for Navigational Message DL2C ...... 119
Table 5.5.2-11 Definition of GPS GNSS Time Offset (GGTO) parameters for Navigational
Message DL2C .................................................................................................................120
Table 5.6.2-1 Definitions of message types for Navigational Message DL5 .......................122
Table 5.6.2-2 Maximum Transmit Intervals for Navigational Message DL5 .....................123
Table 5.6.2-3 Definition of Ephemeris parameters for Navigational Message D L5 ..........125
Table 5.6.2-4 Definition of SV clock parameters for Navigational Message D L5 ..............127
Table 5.6.2-5 Definition of ionospheric parameters for Navigational Message D L5 .........128
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Table 5.6.2-6 Group Delay Differential Correction Parameters (TGD, ISC) for Navigational
Message D L5 ..................................................................................................................129
Table 5.6.2-7 Ephemeris related parameter (WNop) for Navigational Message DL2C .......129
Table 5.6.2-8 Definition of Midi Almanac parameters for Navigational Message DL5 ......130
Table 5.6.2-9 Definition of Reduced Almanac parameters for Navigational Message DL5131
Table 5.6.2-10 Definition of parameters for DC data for Navigational Message DL5........135
Table 5.6.2-11 Definition of GPS GNSS Time Offset (GGTO) parameters for Navigational
Message DL5 ..................................................................................................................136
Table 5.7.1-1 LEX code phase assignment ..........................................................................139
Table 5.7.2-1 Definition of message type.............................................................................141
Table 5.7.2-2 Definition of ephemeris parameters for Navigational Message DLEX navigation
message .........................................................................................................................150
Table 5.7.2-3 Definition of SV clock and group delay differential correction parameters for
Navigational Message DLEX navigation messages .......................................................154
Table 5.7.2-4 Definition of ionospheric correction parameters for LEX navigation messages
.......................................................................................................................................155
Table 5.7.2-5 Message type 10,11: transmitting interval, update interval and validity period
.......................................................................................................................................158
Table 5.7.2-6 Message type number list of SSR Packet transmitted by MADOCA-LEX
Message .........................................................................................................................161
Table 5.7.2-7 SSR GPS Orbit Correction Messages (Message Type Number: 1057) .........163
Table 5.7.2-8 SSR QZSS Orbit Correction Messages (Message Type Number: 1246) .......164
Table 5.7.2-9 QZSS Satellite ID ...........................................................................................165
Table 5.7.2-10 SSR Galileo Orbit Correction Messages (Message Type Number: 1240) ..166
Table 5.7.2-11 SSR GLONASS Orbit Correction Messages (Message Type Number: 1057)
.......................................................................................................................................167
Table 5.7.2-12 SSR GPS Code Bias Correction Messages (Message Type Number: 1059)
.......................................................................................................................................168
Table 5.7.2-13 SSR QZSS Code Bias Correction Messages (Message Type Number: 1248)
.......................................................................................................................................169
Table 5.7.2-14 Indicator to specify the QZSS signal and tracking .....................................170
Table 5.7.2-15 SSR Galileo Code Bias Correction Messages (Message Type Number: 1059)
.......................................................................................................................................171
Table 5.7.2-16 SSR GLONASS Code Bias Correction Messages (Message Type Number:
1059) ..............................................................................................................................172
Table 5.7.2-17 SSR GPS URA Messages (Message Type Number: 1061) ..........................173
Table 5.7.2-18 SSR QZSS URA Messages (Message Type Number: 1250) ........................174
Table 5.7.2-19 SSR Galileo URA Messages (Message Type Number: 1244) ......................175
Table 5.7.2-20 SSR GLONASS URA Messages (Message Type Number: 1061) ................176
Table 5.7.2-21 SSR GPS High Rate Clock Correction Messages (Message Type Number:
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1062) ..............................................................................................................................177
Table 5.7.2-22 SSR QZSS High Rate Clock Correction Messages (Message Type Number:
1248) ..............................................................................................................................178
Table 5.7.2-23 SSR Galileo High Rate Clock Correction Messages (Message Type Number:
1242) ..............................................................................................................................179
Table 5.7.2-24 SSR GLONASS High Rate Clock Correction Messages (Message Type
Number: 1065)...............................................................................................................180
Table 5.7.2-25 Update intervals of the SSR Messages in message type 12. ......................181
Table 6.4.1-1 Validity Periods for L1-SAIF Message Parameters ......................................195
Table 6.4.3-1 Relations of integrity and Constants "K" ......................................................202
Table 7.2-1 Provision of QZSS Information and Data ........................................................ 211
Table 7.2.3-1 Test Evaluation Public Release Data List ....................................................212
Table 8.1.1-1 Parameters with definitions unique to QZSS in terms of LNAV message (1/2)
.......................................................................................................................................214
Table 8.1.2-1 Parameters with definitions unique to QZSS in terms of CNAV message (1/2)
.......................................................................................................................................216
Table 8.1.3-1 Parameters with definitions unique to QZSS in terms of CNAV2 message (1/2)
.......................................................................................................................................218
ix
IS-QZSS Ver. 1.6
1 Scope
This Interface Specification (IS-QZSS) presents an overview of the Quasi-Zenith Satellite System
(QZSS 1) being developed by the Japan Aerospace Exploration Agency (JAXA) and defines the interface
between the Space Segment (SS) provided by the Quasi-Zenith Satellites (QZS 2), and the User Segment
(US) of the QZSS. IS-QZSS was prepared to encourage the use of the positioning, navigation and timing
services of QZSS which are freely available for peaceful means to anyone who has visibility to one or
more QZS.
QZSS signals have been designed and developed so as to maximize the interoperability with the
NAVSTAR Global Positioning System (GPS) operated by the United States (U.S.) as well as to provide
compatibility of QZSS with GPS and other space-based systems that comprise the Global Navigation
Satellite System (GNSS). The QZSS signal design reflected in this document was established through
closely collaborated discussion with in the U.S.-Japan GPS QZSS Technical Working Group.
IS-QZSS provides general information regarding the QZSS system and services and also covers service
performance, QZSS signal characteristics and recommended user algorithms. QZSS is designed to work in
conjunction with, and enhance, the civil services of GPS. Therefore, this document makes reference to the
public domain GPS interface specification documents listed in Section 2 below. IS-QZSS describes in
detail all differences with respect to GPS that user equipment designers must be aware of to make full use
of the enhanced capabilities possible when QZSS signals are received in addition to GPS signals.
This specification is intended for all users of QZSS and includes information about utilizing the L1C/A,
L1C, L1-SAIF (L1-band Submeter-class Augmentation with Integrity Function), L2C, L5 and LEX (Lband EXperiment) signals transmitted by Quasi-Zenith Satellites (QZS).
This IS-QZSS document has been updated several times since the publication of the first draft edition for
QZS-1 due to the progress of the system design and development. In this IS-QZSS Version 1.6 release, the
signal types signal strengths, signal structures, and other elements from the previous release of IS-QZSS
have been updated. JAXA welcomes and encourages feedback from QZSS users. IS-QZSS will be
reviewed and revised in response to valuable user feedback in addition to the status of the QZSS operation
after the launch of the first QZS, etc., from the viewpoints of manner of operation, handling of data,
readability, and others. Upon the release of the next revision of IS-QZSS, the comments of users will again
be taken into consideration.
1
2
QZSS is an abbreviation for Quasi Zenith Satellite System and refers to the system as a whole.
QZS is an abbreviation for Quasi Zenith Satellite and refers specifically to these satellites.
1
IS-QZSS Ver. 1.6
Application demonstration will be mainly conducted by the private sector. Satellite Positioning Research
and Application Center (SPAC) will be a coordinator for user interface among related organizations.
Section 3 of IS-QZSS presents an overview of the Quasi-Zenith Satellite System. The availability,
geographical coverage and system performance provided by QZSS are introduced in Section 4. Sections 5
to 8 contain the details of the interface specification and signal description. Section 5 specifies the QZSS
signal properties including RF characteristics, message structure and data format. Section 6 contains user
algorithms to be incorporated in receiver designs. Section 7 provides information regarding obtaining
QZSS operational data via the internet. Finally, the differences between QZSS and GPS messages are
summarized in Section 8 for the convenience of users.
The specification for L1-SAIF signal in Section 4.3.2 "Alert flag, URA, Health Data", Section 4.3.3.5
"Positioning Accuracy by means of Performance Enhancement Signals", Section 5.4 "L1-SAIF signal" and
Section 6.4 "L1 SAIF Algorithm" are development results by Electronic Navigation Research Institute.
And also, the information about "L1-SAIF+ message" in Section 5.4.3.1.2 and 5.4.3.5 reflects the fruits of
research and development by Satellite Positioning Research and Application Center. The detailed
specification defined the interface have been issued by Satellite Positioning Research and Application
Center separately (in Section 2 "Applicable Document" (6)).
The detailed specifications for messages type 156 - 255 in Section 5.7.2.2.4 have been issued by Satellite
Positioning Research and Application Center (in Section 2 "Applicable Document" (6)).
2
IS-QZSS Ver. 1.6
2 Applicable Documents
(1)
Navstar GPS Space Segment/Navigation User Interface, Interface Specification, IS-GPS-200. Rev.
H, Sept. 2013.
(2)
Navstar GPS Space Segment/User Segment L5 Interfaces, Interface Specification, IS-GPS-705.
Rev. D, Sept. 2013.
(3)
Navstar GPS Space Segment/User Segment L1C Interfaces, Interface Specification, IS-GPS-800.
Rev. D, June 2013.
(4)
International Standards and Recommended Practices, Aeronautical Telecommunications, Annex 10
to the Convention on International Civil Aviation, vol. I, ICAO, Nov. 2002.
(5)
Minimum Operational Performance Standards for Global Positioning System/Wide Area
Augmentation System Airborne Equipment, DO-229C, RTCA, Nov. 2001.
(6)
SPAC-RI-100630-15, Augmentation Message Specification for Application Demonstration with
Quazi-Zenith Satellite System, Satellite Positioning Research and Application Center, May 2014.
(7)
RTCM SPECIAL COMMITTEE NO. 104, RTCM Paper 228-2013-SC104-STD, RTCM
STANDARD 10403.2 DIFFERENTIAL GNSS (GLOBAL NAVIGATION SATELLITE SYSTEMS)
SERVICES – VERSION 3 with Amendment 2, Nov, 2013.
3
IS-QZSS Ver. 1.6
3 Overview of QZSS
The Quasi-Zenith Satellite System (QZSS) is a regional space-based positioning system that uses a
constellation of satellites placed in multiple orbital planes. The satellites have the same orbital period as a
traditional equatorial geostationary orbit, however, they have a large orbital inclination and therefore move
with respect to the Earth. The QZS orbits are also elliptical and are sometimes known as "highly-inclined
elliptical orbits" or HEO. The system covers regions in East Asia and Oceania centering on Japan and is
designed to enable users in the coverage area to receive QZS signals from a high elevation angle at all
times.
QZSS enhances GPS services in the following two ways: 1) Availability enhancement (improving the
availability of GPS signals) and 2) Performance enhancement (increasing the accuracy and reliability of
GPS signals).
By broadcasting signals that are similar to and compatible with GPS, QZSS enhances standalone GPS
availability for any user that has visibility to, and can track, one or more QZS. This enhancement will be
the greatest for users in the region of Japan because the constellation design is optimized for that area.
However, users in many other Asia-Pacific areas will also benefit from the enhanced geometric
arrangement made possible by QZSS. This increases the area and times at which positioning is possible in
both urban and mountainous areas where a portion of the sky is often blocked from view.
To ensure interoperability and compatibility with modernized GPS civil signals, the GPS availability
enhancement signals transmitted from QZSS satellites use modernized GPS civil signals as a base,
transmitting the L1C/A, L1C, L2C and L5 signals. This minimizes changes to specifications and receiver
designs. Additionally, L1C and L5 of above signals transmitted by QZSS have interoperability with not
only GPS but also Galileo and other GNSS in future multi-GNSS era.
QZSS further improves standalone GPS accuracy by means of ranging correction data provided through
the transmission of submeter-class performance enhancement signals L1-SAIF and LEX from QZS. It also
improves reliability by means of failure monitoring and system health data notifications. QZSS also
provides other support data to users to improve GPS satellite acquisition.
4
IS-QZSS Ver. 1.6
3.1 Overview of QZSS
3.1.1 System Overview
QZSS consists of (a) the QZSS Space Segment (SS) comprised of a constellation of Quasi-Zenith
Satellites (QZS) orbiting the Earth, and (b) the QZSS Ground Segment (GS) comprised of Monitor
Stations (MS), a Master Control Station (MCS), Tracking Control Stations (TCS) and Time
Management Station (TMS). A system diagram is provided in Figure 3.1.1-1.
QZS signals are transmitted from the QZS and monitored by the MS. The MCS collects the MS
monitoring results and estimates and predicts the QZS time and orbit. The MCS also gathers other data
as well and generates navigation messages, and uplinks to the QZS via the Tracking Control Station.
The Tracking Control Stations constantly monitor the status of the QZS and function in cooperation
with the MCS to provide appropriate services as needed. In addition, approximately once per year, the
TCS exercise orbital control to ensure that the QZS is maintained in the correct orbital position.
Figure 3.1.1-1 System overview
3.1.1.1 Overview of QZSS Space Segment
The QZSS Space Segment (SS) consists of initially one satellite, and ultimately three (or more)
satellites having the characteristics described below.
3.1.1.1.1 QZSS Constellations
The baseline QZSS constellation is comprised of three satellites as illustrated below. All QZS are
in orbits that have the same "figure-8" ground track (passing over Southeast Asia, Australia, etc.)
as shown in Figure 3.1.1-2 and Figure 3.1.1-4. The orbit tracks of the 3 satellites are shown in Figure
3.1.1-3.
5
IS-QZSS Ver. 1.6
Figure 3.1.1-2 QZSS Orbit and Ground Track Diagram for the Three-Satellite Constellation
Figure 3.1.1-3 Constellation Orbit Track Diagram (EPOCH=2009/Dec/26/12:00UTC) for the
Three-Satellite Constellation
6
IS-QZSS Ver. 1.6
3.1.1.1.2 Orbits
The parameters defining the QZS nominal orbits are provided below. The satellites have the same
orbital period as a traditional equatorial geostationary satellite (about 23 hours 56 minutes), however,
they have a large orbital inclination so they do not remain in the equatorial plane and therefore move
with respect to the Earth. The QZS orbits are also elliptical and are sometimes known as "highlyinclined elliptical orbits" or HEO. The QZS will orbit somewhat further from the Earth in the
Northern Hemisphere than in the Southern Hemisphere. These orbits result in a longer period of
high elevation angle service for the region of Japan. Ultimately a single satellite will be deployed
in each of the three orbital planes, thereby providing continuous coverage at high elevation angles
for the primary service areas (including all Japanese territory).
3.1.1.1.2.1 Semi-Major Axis (A)
A = 42164 [km] (average)
3.1.1.1.2.2 Eccentricity (e)
e = 0.075 ± 0.015
3.1.1.1.2.3 Orbital inclination (i)
i = 43°± 4°
3.1.1.1.2.4 Right Ascension of Ascending Node (Ω)
With the argument of perigee, the right ascension of ascending node for each satellite is designed
to maintain the central longitude of the ground track (see Section 3.1.1.1.2.6). The initial right
ascension of ascending node of Quasi-Zenith Satellite-1 (QZS-1) Ω0 is set at about 195 [deg].
3.1.1.1.2.5 Argument of Perigee (ω)
ω = 270°± 2°
3.1.1.1.2.6 Central Longitude of Ground Trace
The central longitude of ground trace is the center of the 8-figure ground trace, and is the center
of two longitudes of ascending and descending. The longitude value is maintained 135° East ±
5°. (The range of the central longitude might exceed ± 5° in order to improve the availability with
the high elevation property of QZS-1.)
7
IS-QZSS Ver. 1.6
3.1.1.1.3 QZS orbit Ground Tracks
Figure 3.1.1-4 shows the QZS orbit ground tracks (See Table 3.1.1-1 for calculation condition).
Figure 3.1.1-4 QZS Orbit Ground Tracks
Table 3.1.1-1 Calculation condition for QZS-1 nominal orbit
No.
Item
Setting
1
Epoch
26 Dec. 2009, 12:00:00 (UTC)
2
Semi-Major Axis [km]
42164.16945
3
Eccentricity
0.075
4
Orbital inclination [deg]
43.0
5
Right Ascension of Ascending Node [deg]
195.0
6
Argument of Perigee [deg]
270.0
7
Mean Anomaly [deg]
305.0
3.1.1.1.4 QZS
Figure 3.1.1-5 shows an illustration of a QZS. It has two deployable solar cell array panels, an Lband transmission antenna (L-ANT), an L1-SAIF transmission antenna (LS-ANT), Telemetry,
Tracking and Command (TT&C) antennas, and a Ku-band Time Transfer Antenna (Ku-ANT). The
QZS utilizes fixed (non-steerable) antennas mounted on one side of the spacecraft. The QZS attitude
is controlled to ensure that these antennas always point toward the center of the Earth. Yaw steering
controls the orientation of the solar cell arrays to optimize reception of sunlight.
The L-ANT is made up of a helical antenna array. The gain curve formed by this array is designed
to provide signals with constant power levels at any location on the ground by compensating for the
Earth’s surface shape.
8
IS-QZSS Ver. 1.6
Ku-ANT
Solar Paddle
TT&C Antenna
L-ANT
LS-ANT
Figure 3.1.1-5 QZS
The QZS includes the equipment shown in Figure 3.1.1-6 that is used to generate and transmit QZS
signals. QZS signals comprise a carrier wave that uses a rubidium atomic clock as a frequency
reference and that is modulated by PRN (Pseudo-Random Noise) codes and navigation messages
generated by the MCS. These signals are transmitted toward the Earth from the L-ANT and LSANT.
QZS
L1-SAIF-Ant
Rb
Atomic
ＲｂAtomic
Clock
Clock
Time
Time
Keeping
Keeping
Unit
Unit
Synthesizer
Synthesizer
Navigation
Navigation
Onboard
Operation
Computer
Computer
Modulator
Modulator
Amplifier
Amplifier
MUX
L-Ant
TLM
Control
Phase Error
Navigation Message, CMD
TT&C
Subsystem
TT&C
Uploaded Data
(including Remote Synchronization
Signal)
Navigation Signal
Time
Time
Comparison
Comparison
Unit
Unit
Laser
Reflector
Time Transfer
Time Transfer
System
System
RF portion
RF portion
Sine Wave
Baseband Signal (Navigation Message + PRN Code)
Ku-Ant
Signal of Two Way Satellite Time and Frequency Transfer
Figure 3.1.1-6 QZS Block Diagram
3.1.1.2 Overview of Ground Segment
The QZSS Ground Segment consists of multiple Earth-based stations. These comprise Monitor
Stations (MS) that are widely distributed and observe QZS and GPS signals on the ground; a Master
Control Station (MCS) that collects the results of monitoring from all of the MS, estimates and
predicts QZSS and GPS clock offsets and orbits, generates navigation messages, etc.; Tracking
Control Stations that uplink navigation messages and monitor QZS status, and the Time Management
Station (TMS) for time transfer.
There are nine MS dispersed throughout the area from which QZS signals can be received (Refer to
Figure 3.1.1-7). The MCS (Refer to Figure 3.1.1-8) and TMS are located in Japan. The rough locations
of each Ground Stations are shown in Table 3.1.1-2.
9
IS-QZSS Ver. 1.6
90
Sarobetsu
60
Koganei
Latitude
Tsukuba
Okinawa
30
Hawaii
Bangalore
0
Chichijima
Guam
Bangkok
-30
Master Control Station
QZSS Monitor Station
Tracking Control Station
Canberra
-60
-90
0
30
60
90
120
150
180
210
240
270
300
330
Longitude
Figure 3.1.1-7 Mapping of Ground Stations
Table 3.1.1-2 Location of Ground Station
No.
Place
Location (Longitude and Latitude)
1
Koganei
East longitude
139.4882°
North latitude
35.7078°
2
Sarobetsu
East longitude
141.7489°
North latitude
45.1636°
3
Okinawa
East longitude
127.8444°
North latitude
26.4986°
4
Chichi-Jima
East longitude
142.2154°
North latitude
27.0792°
5
Hawaii
West longitude
159.6650°
North latitude
22.1262°
6
Guam
East longitude
144.7948°
North latitude
13.4774°
7
Bangkok
East longitude
100.6130°
North latitude
14.0823°
8
Bangalore
East longitude
77.5116°
North latitude
13.0343°
9
Canberra
East longitude
149.0104°
South latitude
35.3160°
10
360
IS-QZSS Ver. 1.6
Figure 3.1.1-8 MCS
Several Tracking Control Stations are strategically positioned at locations that enable continuous
monitoring and control of the QZS. Two Tracking Control Stations are constructed in the Okinawa
Tracking and Communication Station for the first development phase of Quasi-Zenith Satellite System.
Figure 3.1.1-9 shows the type of TT&C antenna with which each Tracking Control Station is equipped.
Figure 3.1.1-9 TT&C Antenna
11
IS-QZSS Ver. 1.6
3.1.2 Operation
3.1.2.1 Data
3.1.2.1.1 Data Flow
Figure 3.1.2-1 shows an overview of the QZSS data flow.
(1) QZS signals and signals from other GNSS are received by the Monitor Stations
(MS).
(2) The results of monitoring by the MS are sent to the Master Control Station (MCS)
where QZSS and other GNSS orbits and times are estimated and propagated to
predict future satellite positions and system times.
(3) Based on the results of orbit and time estimates and predictions, navigation
messages are generated and sent to the Tracking Control Stations.
(4) At the Tracking Control Stations, the navigation messages are uploaded to the QZS
On-board Control Computer by way of the Telemetry Command Subsystem.
(5) On-board the QZS, a signal with the navigation messages superimposed are
generated and transmitted to the Earth via the L-band transmission antenna and the
L1-SAIF transmission antenna.
Figure 3.1.2-1 System data flow
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IS-QZSS Ver. 1.6
3.1.2.1.2 Navigation Message Update and Uplink
The navigation messages in the QZS signals, except the L1-SAIF and LEX signals, are updated
with the timing shown in Figure 3.1.2-2. For this purpose, QZSS uplinks the appropriate navigation
messages at the necessary intervals by way of the Tracking Control Stations.
Ephemeris data (including SV Clock parameters) are updated every 900 seconds (at minimum).
URA of the signals are updated every 30 seconds for L1C/A, every 18 seconds for L1C, every 48
seconds for L2C and every 24 seconds for L5. Other information are depends on navigation pattern
table (see Section 7.2.4.3). Orbit Parameters of Ephemeris data is valid for 7200 seconds (at
minimum), and SV Clock Parameters are valid for 1800 seconds (at minimum).
The navigation messages of the L1-SAIF and LEX signals are uploaded from MCS, superimposed
upon navigation signals on QZS and transmitted to the Earth continuously.
Time of Week
00:00:00
(Week Number = n)
TOW
00:00:00
(WN = n+1)
1week = 604800s
(1) Other than (2)(3)
(2) Ephemeris, SV Clock
Parameter
3600s
900s
900s
3600s
900s
900s
900s
900s
300s
300s
300s
300s
3600s
900s
900s
900s
900s
900s
900s
900s
300s
300s
(3) Differential Data
Figure 3.1.2-2 An example of the update timing of the navigation message
13
IS-QZSS Ver. 1.6
Further Navigation message timing details are provided in Figure 3.1.2-3.
5min(300s)
Hour
(Overall message update)
Hour
(Overall message update)
time
Overall message
at 15-min intervals
L1C/A
Ephemeris, Clock
at 30-s intervals
URA INDEX, NMCT,
AODO
Overall message
at 15-min intervals
Ephemeris, Clock
L2C
at 5-min intervals
EDC, CDC
at 48-s intervals
URA INDEX
Overall message
at 15-min intervals
Ephemeris, Clock
at 5-min intervals
L5
EDC, CDC
at 24-s intervals
URA INDEX
Overall message
at 15-min intervals
Ephemeris, Clock
L1C
at 5-min intervals
EDC, CDC
at 18-s intervals
URA INDEX
Figure 3.1.2-3 An example of uplink timing of the navigation message
3.1.2.1.3 Uplink of "Alert" Flag, URA, Health Data and Differential Data
The "Alert" flag, URA, Health data and differential data described below are transmitted to the user
by QZSS on the L1C/A, L1C, L2C, L5 and LEX signals. See Section 5.4 for information regarding
the L1-SAIF signal.
3.1.2.1.3.1 "Alert" flag (on L1C/A, L1C, L2C, L5 and LEX)
QZSS monitors QZS signals and status and, once per second, makes a determination as to whether
or not the Signal-In-Space (SIS) accuracy of any QZS signal is worse than 9.65 [m] and whether
there is any detected problem with the QZS. If the determination is that a QZS signal is not
suitable for use, the user is notified within the time limits specified for each signal in Section
4.3.2.2, of the detection of the problem via the corresponding "Alert" flag.
Also when the QZS is in its maintenance operations which are described in Section 3.1.2.2.1.1
and Section 3.1.2.2.1.2, the "Alert" flag in its navigation message is set to indicate it to users and
to notify to users that the QZS signal cannot be used.
14
IS-QZSS Ver. 1.6
3.1.2.1.3.2 URA (on L1C/A, L1C, L2C, L5 and LEX)
URA stands for "User Range Accuracy". The SIS accuracy, quantified as URA, is reported in a
timely manner when the Ephemeris data being provided to the user and the SV clock parameters
are used.
QZSS monitors the QZS signals and, once per second, estimates the SIS accuracy of the signals
in the direction of the QZS Line of Sight vector. The data are uploaded to the QZS within the time
limits specified for each signal in Section 4.3.2.2, and the absolute value of the estimated URA
(SIS accuracy) will be sent to the user within 30 seconds of the corresponding QZS signal
transmission from MCS.
3.1.2.1.3.3 Health Data (on L1C/A, L1C, L2C, L5 and LEX)
QZSS monitors the QZS signals and QZS status and, once per second, makes a determination as
to power level, modulation status and whether or not any message errors have occurred. At the
same time, QZSS also monitors the signals of SVs of other GNSS systems and judges power level
and modulation status, and, once per second estimates the SIS accuracy of these signals. The data
are uploaded to the QZS immediately at the time when abnormal events are detected or confirmed
that events are ended and return to nominal condition, therefore the users will be notified of the
results within the seconds, which is specified in Section 4.3.2.2, of the corresponding QZS and
other SV signal transmissions.
3.1.2.1.3.4 NMCT (on L1C/A), EDC and CDC (on L1C, L2C and L5)
NMCT stands for "Navigation Message Correction Table". EDC stands for "Ephemeris
Differential Correction". CDC stands for "Clock Differential Correction". By using the
differential data provided by QZSS in these three correction terms, user receivers are able to
mathematically remove most of the errors inherent in the Ephemeris data and SV clock parameters.
QZSS monitors the QZS signals and the signals of other GNSS systems and, once per second,
estimates the SIS error in the direction of the Line of Sight vector. The results of these estimates
are uploaded to the QZS every 30 seconds for NMCT, and 300 seconds for EDC and CDC, as
differential data.
d
UDRA (on L1C, L2C and L5)
dt
UDRA stands for "User Differential Range Accuracy". This value is used together with its time
d
UDRA , to enable users to determine the SIS accuracy after correction with the
derivative,
dt
EDC and CDC.
3.1.2.1.3.5 UDRA and
This indicates the accuracy of the SIS error estimates calculated by the QZSS MCS in the
direction of the Line of Sight vector for QZS signals and the signals of other GNSS systems. The
value is uploaded to the QZS every 300 seconds.
3.1.2.1.3.6 NSC switching
NSC stands for "Non-Standard Code".
The NSC is an invalid pseudo-random noise (PRN) code sequence (i.e., one that is not valid for
use by any GNSS receiver). An operator of QZSS may switch manually from transmitting its
normal ranging PRN code to transmitting the NSC to protect users under a system error.
At such times, the transmission of NSC will ensure that users are not able to receive signals from
the affected QZS. The time to switch to NSC from standard PRN code is within 15 seconds.
15
IS-QZSS Ver. 1.6
・Other system error has occurred (Manually)
URA broadcast
・URA exceeds value which is assured in this specification
Error Occurs
／maintenance
(Automatically)
・Actual URA exceeds index which has been broadcasted (Automatically)
・SIS accuracy exceeds the range by the URA’s bit length (Automatically)
・The QZS can not be used because of the maintenance (Manually)
Alert flag
broadcast
investigation
・If corrected→Alert canceled (Manually)
Switch to NSC
・If corrected→Alert canceled (Manually), switch to standard code
(Manually)
investigation
・If not corrected→broadcast suspended (Manually)
Figure 3.1.2-4 Relationship between "Alert" flag and URA/NSC switching
3.1.2.2 Maintenance, Failure, Restoration and Testing
3.1.2.2.1 Satellite System Maintenance
Two or more QZS will never halt service at the same time due to the orbit maintenance or attitude
maintenance described below.
3.1.2.2.1.1 Orbit Maintenance
The QZS orbit is affected by forces of various types (the Earth's gravitation, the solar radiation
and etc.). As a result, it will slowly drift from its intended orbit. For this reason, QZSS conducts
orbit maintenance once every 150 days (average). Service is halted for up to two days during orbit
maintenance.
The notification way of the orbit maintenance information to the users are referred to chapter
7.2.1. Moreover, immediately prior to orbit maintenance, the "Alert" flag is set to "1". When orbit
maintenance is complete, the "Alert" flag is cleared (set to "0").
As a result of orbit maintenance, the QZS orbit will be maintained within the range shown in
Figure 3.1.2-5.
16
IS-QZSS Ver. 1.6
: Nominal (See Section 3.1.1.1.2)
: Nominal longitude of ascending
+/- 5[deg.]
: Nominal Inclination +/- 4[deg.]
Figure 3.1.2-5 Range of Orbital Maintenance
3.1.2.2.1.2 Momentum Management
The attitude of the QZS is affected primarily by the solar radiation pressure. The solar radiation
pressure is absorbed by reaction wheels on the QZS to prevent it from affecting the QZS attitude.
However, once per more than 30 days (average 40 days), momentum management (in which this
angular momentum is unloaded) must be performed. During this momentum unloading process,
service will be halted for a period of up to one day.
Users will be notified in advance regarding the occurrence of the unloading process through the
medium of the Internet, etc. Moreover, immediately before unloading, the "Alert" flag is set to
"1". When unloading is complete, the "Alert" flag is cleared (set to "0").
3.1.2.2.1.3 QZS failure and restoration
In the event that a certain QZS experiences an unexpected satellite-wide failure, notification of
the failure of that QZS is sent from another QZS by means of the Navigation message (see Section
5.1.2.1.3). Transmission of the QZS signals from the failed QZS is halted or switched over to
NSC.
In the event that one of the sub-systems in a certain QZS fails, notification of the failure and repair
of that sub-system is sent by means of the Navigation message (see Section 5.1.2.1.3) using
signals that include identification of any remaining valid signals of that QZS.
In addition, users are notified regarding the status of these systems through the medium of the
Internet, etc shown in Section 7 of "PROVISION OF QZSS OPERATIONAL INFORMATION
AND DATA VIA THE INTERNET".
3.1.2.2.2 Ground Segment system maintenance
Ground Segment maintenance will be performed in a manner that does not adversely affect QZSS
availability.
17
IS-QZSS Ver. 1.6
3.1.2.2.3 Testing
Depending on the nature of the tests, it may not always be possible to provide the specified
positioning performance to users during certain QZSS tests. At such times, the standard transmitted
PRN codes may be switched to NSC in order to protect users. In such cases, users will generally be
given advance notice through the medium of the Internet, etc shown in Section 7 of "PROVISION
OF QZSS OPERATIONAL INFORMATION AND DATA VIA THE INTERNET" regarding the
period of time during which such testing will occur.
3.1.3 Signals transmitted by QZS = QZS Signals
3.1.3.1 Types of Signals Transmitted by QZS
QZSS satellites transmit six positioning signals: L1C/A signal, L1-SAIF signal, L1C signal, L2C
signal, LEX signal and L5 signal. Four of these -- L1C/A, L1C, L2C and L5 -- are known as
positioning availability enhancement signals (or simply availability enhancement signals) in the sense
that they complement the existing Global Navigation Satellite System (GNSS). The remaining two
signals -- L1-SAIF and LEX -- are known as positioning performance enhancement signals (or simply
performance enhancement signals) in the sense that they enhance performance through the
transmission of existing GNSS differential data and integrity data concerning GNSS signals as
determined by QZSS.
3.1.3.2 Spectrum of QZS Signals
The six positioning signals transmitted by QZS have four center frequencies. With the reference
frequency set to f0= 10.23[MHz], these carrier frequencies are 154×f0 for L1, 125×f0 for LEX, 120×f0
for L2, 115×f0 for L5.
Figure 3.1.3-1 shows the power spectral density of the six QZS signals versus frequency. Note that
this is the power spectral density at the input of user antenna on the ground.
L2 center frequency: 1227.60 [MHz]
L5 center frequency: 1176.45 [MHz]
L1 center frequency: 1575.42 [MHz]
LEX center frequency: 1278.75 [MHz]
Power Spectral Density (dB(W/Hz))
-215
L2C
-220
L1C
L1C/A
L1-SAIF
LEX
L5
-225
-230
-235
-240
-245
-250
-255
-260
1125.30
1176.45
1227.60
1278.75
1329.90
1585.65
Frequency (MHz)
Figure 3.1.3-1 Power Spectral Density of QZS Signals
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IS-QZSS Ver. 1.6
3.1.3.3 General Specifications for QZS Signals
Table 3.1.3-1 shows the general specifications for QZS signals.
Table 3.1.3-1 General Specifications for QZS Signals
I/Q channel
Spreading
Signal name
Center frequency
identification
frequency
L1C/A *
L1C *
1575.42[MHz]
L1-SAIF
L2C *
1227.60[MHz]
L5 *
1176.45[MHz]
LEX
1278.75[MHz]
–
0.1 × f0
Data channel
0.1 × f0
Pilot channel
0.1 × f0
–
–
(2 channels time
multiplexed)
I channel
0.1 × f0
1 × f0
Q channel
1 × f0
–
*GPS availability enhancement signal
19
0.1 × f0
0.5 × f0
IS-QZSS Ver. 1.6
3.1.3.4 QZS Signal Doppler
The Doppler values for QZS signals received at eight reference locations equals to Relative velocity
of signals (Change rate of distance) between each city and QZS-1 (shown in Figure 3.1.3-2) multiplied
by the Doppler coefficients for each positioning signal frequency (Center frequency/Speed of light)
(listed in Table 3.1.3-2).
600
600
400
400
Relative Velocity (m/sec)
Relative Velocity (m/sec)
In Figure 3.1.3-2, the gaps in the plots of relative velocity correspond to times when the QZS is below
10 degrees elevation angle for the corresponding location. The upper and lower solid lines represent
the upper and lower ranges of the relative velocity, respectively.
200
0
-200
-400
-600
200
0
-200
-400
-600
0
3
6
9
12
15
Time (Hr)
18
21
24
0
3
6
600
400
400
200
0
-200
-400
-600
21
24
18
21
24
18
21
24
18
21
24
200
0
-200
-400
3
6
9
12
15
Time (Hr)
18
21
24
0
3
6
9
Okinawa
12
15
Time (Hr)
Seoul
600
600
400
400
Relative Velocity (m/sec)
Relative Velocity (m/sec)
18
-600
0
200
0
-200
-400
-600
200
0
-200
-400
-600
0
3
6
9
12
15
Time (Hr)
18
21
24
0
3
6
Bangkok
9
12
15
Time (Hr)
Singapore
600
600
400
400
Relative Velocity (m/sec)
Relative Velocity (m/sec)
12
15
Time (Hr)
Tokyo
600
Relative Velocity (m/sec)
Relative Velocity (m/sec)
Wakkanai (Hokkaido, Japan)
9
200
0
-200
-400
-600
200
0
-200
-400
-600
0
3
6
9
12
15
Time (Hr)
18
21
24
Sydney
0
3
6
9
12
15
Time (Hr)
Perth
Figure 3.1.3-2 Examples of relative velocity of signals (Change rate of distance) between each
city and QZS-1 (See Table 3.1.1-1 for calculation condition. Observation EPOCH =
2009/Dec/26/12:00UTC. Horizontal axis means elapsed time from EPOCH.)
20
IS-QZSS Ver. 1.6
Table 3.1.3-2 Doppler coefficients for signals
Signal
Doppler scale
L1C/A, L1C, L1-SAIF
5.3
L2C
4.1
L5
3.9
LEX
4.3
21
IS-QZSS Ver. 1.6
3.1.3.5 Elevation and Azimuthal Angles
Examples of the plots of elevational and azimuthal angles to QZS for eight reference locations are
shown in Figure 3.1.3-3 as they vary over the course of the QZS orbit.
N
N
10
10
30
30
60
60
W
E
W
E
S
S
Wakkanai (Hokkaido, Japan)
Tokyo
N
N
10
10
30
30
60
60
W
E
E
W
S
S
Okinawa
Seoul
N
N
10
10
30
30
60
60
W
W
E
E
S
S
Bangkok
Singapore
N
N
10
10
30
30
60
60
W
W
E
E
S
S
Sydney
Perth
Figure 3.1.3-3 Examples of Elevational and Azimuthal angles for each city (See Table 3.1.1-1
for calculation condition. Observation EPOCH = 2009/Dec/26/12:00 UTC)
22
IS-QZSS Ver. 1.6
3.1.3.6 Received Signal Power Level at Reference Locations
Examples of the User Received Power Levels for each QZS signal at eight reference locations are
shown in Figure 3.1.3-4 as a function of time as they vary over the course of the QZS orbit.
In Figure 3.1.3-4, the gaps in the plots of signal power correspond to times when the QZS is below
10 degrees elevation angle for the corresponding location.
-150
-150
-152
L5
-154
LEX
-156
L1C
L1-C/A
L2C
L1-SAIF
-158
-160
URP (dBW)
URP (dBW)
-152
L5
-154
LEX
-156
L1C
L1-C/A
L2C
L1-SAIF
-158
-160
-162
-162
0
3
6
9
12
15
18
21
24
0
3
6
9
12
Time (Hr)
Wakkanai (Hokkaido, Japan)
L5
-152
LEX
-154
URP (dBW)
URP (dBW)
21
24
15
18
21
24
15
18
21
24
18
21
24
-150
-152
L1C
-156
L1-C/A
-158
L2C
L1-SAIF
-160
L5
-154
LEX
-156
L1C
L1-C/A
L2C
L1-SAIF
-158
-160
-162
-162
0
3
6
9
12
15
18
21
24
0
3
6
9
12
Time (Hr)
Time (Hr)
Okinawa
Seoul
-150
-150
L5
-152
-154
L1C
-156
L5
LEX
-152
LEX
URP (dBW)
URP (dBW)
18
Tokyo
-150
L1-C/A
-158
L2C
-154
L1C
-156
L1-C/A
L2C
-158
L1-SAIF
L1-SAIF
-160
-160
-162
-162
0
3
6
9
12
15
18
21
24
0
3
6
9
Time (Hr)
12
Time (Hr)
Bangkok
Singapore
-150
-150
-152
-152
L5
-154
URP (dBW)
URP (dBW)
15
Time (Hr)
LEX
-156
L1C
-158
L1-C/A
L2C
L1-SAIF
-160
L5
-154
LEX
-156
L1C
-158
L1-C/A
L2C
L1-SAIF
-160
-162
-162
0
3
6
9
12
15
18
21
24
0
Time (Hr)
3
6
9
12
15
Time (Hr)
Sydney
Perth
Figure 3.1.3-4 Examples of changes of received signal power level for each city (See Table
3.1.1-1 for calculation condition. Observation EPOCH = 2009/Dec/26/ 12:00 UTC. Horizontal
axis means elapsed time from EPOCH.)
23
IS-QZSS Ver. 1.6
3.1.4 Time System and Coordinate System
3.1.4.1 Time System
The QZSS time system is called QZSST and has the following characteristics. QZSST conforms to
UTC (NICT) and the offset with respect to the GPS time system, GPST, is controlled.
(1) One-second length
The length of one second is identical to International Atomic Time (TAI). It is also the same for
GPS and Galileo.
(2) Integer second offset for TAI
The integer second offset for TAI is the same as for GPS and TAI is always 19 seconds ahead
of QZSST.
(3) Starting point of Week Number for QZSST
The starting point of the Week Number for QZSST is identical to GPST. Therefore, this
parameter is just referred to as "Week Number" (and not specified as corresponding to QZSST
or GPST).
3.1.4.2 Coordinate System
The QZSS geodetic coordinate system is known as the Japan satellite navigation Geodetic System
(JGS). This coordinate system is defined as follows so as to approach the International Terrestrial
Reference System (ITRS).
(a) Origin:
(b) Z-axis:
(c) X-axis:
(d) Y-axis:
Same as defined for the GRS80 3 ellipsoid (earth’s center of mass)
The geometrical center of the GRS80 ellipsoid is established as the Earth’s
center of mass.
Same as the rotation axis of the GRS80 Ellipsoid.
The direction of the International Earth Rotation and Reference Systems
Service (IERS 4) Reference pole (IRP)
Intersection of the IERS Reference Meridian (IRM) and the equatorial plane
passing through the origin and normal to the Z-axis
Complete a right-handed, Earth-Centered, Earth-Fixed orthogonal coordinate
system
3 Background:
Abbreviation for Geodetic Reference System 1980. GRS80 defines the shape of the earth, gravitational
constants, angular velocity and other physical constants and computational expressions that were adopted in 1979 by the
International Association of Geodesy (IAG) and the International Union of Geodesy and Geophysics (IUGG). In GRS80, the
shape of the ellipsoid, the direction of axes and the earth’s center of gravity were established and define a reference ellipsoid
known as the GRS80 ellipsoid.
4 Background:
Abbreviation for International Earth Rotation and Reference Systems Service. IERS is an international
organization formed with the objective of defining and maintaining a common global standard coordinate system, determining
global time and so on. Its parent organizations are the International Union of Geodesy and Geophysics (IUGG) and the
International Association of Geodesy (IAG).
24
IS-QZSS Ver. 1.6
3.2 Interface with Other Systems
3.2.1 QZSS Time System Relative to Other GNSS
UTC
broadcasted on GPS signal
Steered
<50ns (modulo 1 s)
GPS SV Clock relative to GPST
Normalized frequency
accuracy GST relative to
UTC < 3 x 10^-13
GPS satellites’ Clocks
QZSS satellites’ Clocks
0s
QZSS SV Clock relative to GPST
broadcasted on QZS signal
<5ns (2-sigma)
GPST(GPS-TIME)
GST (GALILEO-TIME)
GALILEO SV Clock relative to GST
broadcasted on GALILLEO signal
GALILEO satellites’ Clocks
GGTO
broadcasted on both GPS
and GALILEO
19s
Steered <50ns,28ns (2-sigma)
TAI
Figure 3.2.1-1 Diagram of Time System Relationships between QZSS, GPS and Galileo
3.2.1.1 Interface with GPS
The SV clocks for QZS and GPS satellites are both controlled with respect to the offset from the GPS
time scale (GPST). The size of the offset is corrected by the SV clock parameter included in the
Navigation message that is transmitted by each satellite.
3.2.1.2 Interface with Galileo
TBD
3.2.2 QZSS Coordinate System Relative to Other GNSS
The GPS coordinate system (WGS84) and the Galileo coordinate system have been prepared so as to
approach ITRS (the International Terrestrial Reference System). Accordingly, under the definition of
JGS in Section 3.1.4, all systems are operated so the differences are maintained as specified in Section
4.3.3.2.2.
Figure 3.2.2-1 shows a conceptual diagram of the relationships between past and future geodetic
coordinate systems. Note that as time moves on, all systems are expected to converge toward ITRS.
25
IS-QZSS Ver. 1.6
Figure 3.2.2-1 Convergence of Geodetic Coordinate Systems
26
IS-QZSS Ver. 1.6
4 QZSS Coverage, Availability and Performance
4.1 QZSS Service Area
4.1.1 Single QZS Coverage Area
Figure 4.1.1-1 and Figure 4.1.1-2 show the availability (the percentage of time during which the
specified minimum elevation angle condition is fulfilled) of a single QZS satellite across the surface of
the Earth.
Figure 4.1.1-1 Percentage of Time during which a Single QZS can be seen at an Elevation
Angle of 10° or more
Figure 4.1.1-2 Percentage of Time during which a Single QZS can be seen at an Elevation
Angle of 60° or more
27
IS-QZSS Ver. 1.6
4.1.2 QZSS Coverage Area
Figure 4.1.2-1 and Figure 4.1.2-2 show the availability (the percentage of time during which the
specified minimum elevation angle condition is fulfilled) of a single QZS across the surface of the Earth
due to the QZSS constellation. For the 3-satellite QZSS constellation (It is assumed that the right
ascension of ascending node for QZS-2 and -3 is ± 120° from that value of QZS-1.), at least one QZS
is available 100% of the time not only in Japan but in almost all parts of Southeast Asia and Oceania at
an elevation angle of 10° or more. In Japan, at least one QZS is available 100% of the time at an elevation
angle of 60° or more.
Figure 4.1.2-1 Percentage of Time during which at least One QZS in the 3-satellite QZSS
constellation can be seen at an Elevation Angle of 10° or more
Figure 4.1.2-2 Percentage of Time during which at least One QZS in the 3-satellite QZSS
constellation can be seen at an Elevation Angle of 60° or more
28
IS-QZSS Ver. 1.6
4.1.3 Elevation Angle Variation for QZSS Constellation
Example for the variation of QZS elevation angles for the 3-satellite QZSS constellation at eight
reference locations is shown in Figure 4.1.3-1 as a function of time as they vary over the course of the
QZS orbit.
QZS1
QZS2
QZS3
0
3
6
9
12
15
Time(Hr)
18
21
90
80
70
60
50
40
30
20
10
0
Elevation Angle (deg)
Elevation Angle (deg)
90
80
70
60
50
40
30
20
10
0
QZS1
QZS2
QZS3
0
24
3
6
9
Wakkanai (Hokkaido, Japan)
6
9
12
15
Time(Hr)
18
21
90
80
70
60
50
40
30
20
10
0
0
24
3
6
9
9
12
15
Time(Hr)
18
21
3
6
9
12
15
Time(Hr)
18
21
18
21
90
80
70
60
50
40
30
20
10
0
Elevation Angle (deg)
Elevation Angle (deg)
9
12
15
Time(Hr)
24
Singapore
QZS1
QZS2
QZS3
6
24
QZS1
QZS2
QZS3
0
24
90
80
70
60
50
40
30
20
10
0
3
21
90
80
70
60
50
40
30
20
10
0
Bangkok
0
18
Elevation Angle (deg)
Elevation Angle (deg)
QZS1
QZS2
QZS3
6
12
15
Time(Hr)
Seoul
90
80
70
60
50
40
30
20
10
0
3
24
QZS1
QZS2
QZS3
Okinawa
0
21
Elevation Angle (deg)
Elevation Angle (deg)
QZS1
QZS2
QZS3
3
18
Tokyo
90
80
70
60
50
40
30
20
10
0
0
12
15
Time(Hr)
QZS1
QZS2
QZS3
0
24
Sydney
3
6
9
12
15
Time(Hr)
Perth
18
21
24
Figure 4.1.3-1 Example for Variation of QZSS Constellation (for 3 satellites) Elevation Angles
for eight cities (See Table 3.1.1-1 for calculation condition of QZS-1. It is assumed that the
right ascension of ascending node for QZS-2 and -3 is ± 120 deg from that value of QZS-1.
Observation EPOCH = 2009/Dec/26/12:00UTC Horizontal axis means elapsed time from
EPOCH.)
29
IS-QZSS Ver. 1.6
4.1.4 QZSS constellation availability
For the 3-satellite QZSS constellation (It is assumed that the right ascension of ascending node for QZS2 and -3 is ± 120° from that value of QZS-1.), Figure 4.1.4-1 shows the average number of QZS satellites
visible from the Earth’s surface. Note that two or more satellites are always visible not only from Japan
but also from virtually every region of Southeast Asia and Oceania as well.
Figure 4.1.4-1 Average Number of QZS Satellites that can be seen at an Elevation Angle of 10°
or more with the 3-satellite QZSS Constellation
4.1.5 Target Regions for Ionospheric Parameters Transmitted by QZS
Each QZS transmits ionospheric parameters that are effective in the geographical regions shown in
Figure 4.1.5-1. The accuracy of these parameters is detailed in Section 4.3.3.3. These ionospheric
parameters should not be used in regions other than those target regions shown in Figure 4.1.5-1. Instead,
ionospheric parameters transmitted by GPS satellites, or GPS ionospheric parameters retransmitted by
the QZS should be used outside of the target regions.
Figure 4.1.5-1 Target Regions for Ionospheric Parameters Transmitted by QZS
30
IS-QZSS Ver. 1.6
4.1.6 Availability Improvement when QZSS and Galileo are combined with GPS
Figure 4.1.6-1 (1/2) and Figure 4.1.6-1 (2/2) show the improvement in GNSS availability when QZSS
(the 3-satellite QZSS constellation : It is assumed that the right ascension of ascending node for QZS-2
and -3 is ± 120° from that value of QZS-1.) and Galileo are combined with the existing GPS
constellation (as of NOV 2006). Each of the two figures includes the cases of GPS alone, GPS with
QZSS and GPS with QZSS and Galileo.
Figure 4.1.6-1 (1/2) and Figure 4.1.6-1 (2/2) provide plots of the percentage of time when the Position
Dilution of Precision (PDOP) is less than 6 for GNSS receiver mask angles of 20° and 40°, respectively.
Figure 4.1.6-2 show the average number of visible satellites for GNSS receiver mask angles of 10°, 20°
and 40°, respectively.
31
IS-QZSS Ver. 1.6
GPS (mask angle 20°)
QZSS + GPS (mask angle 20°)
QZSS + GPS + Galileo (mask angle 20°)
Figure 4.1.6-1 Percentage of Time when PDOP < 6 for an Elevation Angle Mask of 20° and 40°
(1/2)
32
IS-QZSS Ver. 1.6
GPS (mask angle 40°)
QZSS + GPS (mask angle 40°)
QZSS + GPS + Galileo (mask angle 40°)
Figure 4.1.6-1 Percentage of Time when PDOP < 6 for an Elevation Angle Mask of 20° and 40°
(2/2)
33
IS-QZSS Ver. 1.6
GPS (mask angle 10°)
QZSS + GPS (mask angle 10°)
QZSS + GPS + Galileo (mask angle 10°)
Figure 4.1.6-2 Average Number of Visible Satellites for an Elevation Angle Mask of 10°, 20°
and 40° (1/3)
34
IS-QZSS Ver. 1.6
GPS (mask angle 20°)
QZSS + GPS (mask angle 20°)
QZSS + GPS + Galileo (mask angle 20°)
Figure 4.1.6-2 Average Number of Visible Satellites for an Elevation Angle Mask of 10°, 20°
and 40° (2/3)
35
IS-QZSS Ver. 1.6
GPS (mask angle 40°)
QZSS + GPS (mask angle 40°)
QZSS + GPS + Galileo (mask angle 40°)
Figure 4.1.6-2 Average Number of Visible Satellites for an Elevation Angle Mask of 10°, 20°
and 40° (3/3)
36
IS-QZSS Ver. 1.6
4.2 Service Availability
Each QZS transmits positioning signals 24 hours a day, 365 days a year. However, the time
of day during which a particular QZS satellite is visible to a given location varies with the
date.
4.2.1 The fixed initial right ascension of ascending node depending on the launch time
Because the initial right ascension of ascending node was fixed depending on the exact launch time, the
visibility time was also fixed after the launch. For orbital calculation after the QZS-1 launch, the
longitude of the ascending node at weekly epoch would be published as a QZSS almanac via "QZSS
Website for Operational Information and Data" in Section 7.1. The visibility time (from 2014/Jan. to
2014/Dec.) from each location can be seen in Figure 4.2.1-1 (the calculation condition is shown in Table
4.2.1-1).
Table 4.2.1-1 QZS-1 Visibility Time for eight reference locations (from 2014/Jan. to 2014/Dec.)
No.
1
Item
Epoch
2
3
4
5
Semi-Major Axis [km]
Eccentricity
Orbital inclination [deg]
Longitude
of
the
Ascending Node [deg]
Argument of Perigee
[deg]
Mean Anomaly [deg]
6
7
Setting
7 Dec. 2013,
13:00:48 (UTC)
42164.16945
0.075
40.558
145.175
Remark
270.0
Nominal value (see Table 3.1.1-1)
320.194
*1
Nominal value (see Table 3.1.1-1)
Nominal value (see Table 3.1.1-1)
*1
*2
*1 The values of Orbital Inclination and Mean Anomaly are come from Almanac data of the Epoch time.
*2 The values of Longitude of the Ascending Node is modified from almanac data at Epoch time to set the
central longitude of the ground around E135 [deg.].
37
24
9
7
22
7
20
5
20
5
18
3
18
3
16
1
16
1
14
23
14
23
UTC
9
7
20
5
20
5
18
3
18
3
16
1
16
1
14
23
14
23
12
21
12
21
10
19
10
19
8
17
8
17
6
15
6
15
4
13
4
13
2
11
2
11
0
9
0
9
24
9
24
9
22
7
22
7
20
5
20
5
18
3
18
3
16
1
16
1
14
23
14
23
12
21
12
21
10
19
10
19
8
17
8
17
6
15
6
15
4
13
4
13
2
11
2
11
0
9
0
9
24
9
24
9
22
7
22
7
20
5
20
5
18
3
18
3
16
1
16
1
14
23
14
23
12
21
12
21
10
19
10
19
8
17
8
17
6
15
6
15
4
13
4
13
2
11
2
11
0
9
0
9
Dec
2014
Nov
2014
2014
Sep
2014
Oct
Dec
2014
Nov
2014
Sep
Oct
2014
2014
2014
Aug
Jul
2014
May
Jun
2014
2014
Mar
Apr
2014
Feb
2014
2014
Jan
Dec
2014
Nov
2014
Sep
Oct
2014
2014
2014
Aug
Jul
2014
May
Jun
2014
2014
Mar
Apr
2014
Feb
2014
2014
Jan
UTC
2014
Dec
2014
Nov
2014
Sep
Oct
2014
2014
Aug
2014
Jul
2014
May
Jun
2014
2014
Mar
Apr
2014
2014
Aug
UTC
UTC
2014
Dec
2014
Nov
2014
Sep
Oct
2014
2014
Aug
2014
Jul
2014
May
Jun
2014
2014
Mar
Feb
Apr
2014
2014
2014
Feb
2014
2014
2014
Jul
May
Jun
2014
2014
Mar
2014
Apr
Feb
2014
2014
2014
Jan
Dec
2014
Nov
2014
2014
Oct
2014
Sep
2014
Aug
2014
Jul
May
2014
Jun
2014
Mar
2014
Apr
Feb
2014
2014
2014
Jan
Jan
Sydney
JST
2014
Singapore
JST
Jan
Bangkok
JST
2014
Seoul
JST
UTC
JST
JST
UTC
Tokyo
Okinawa
UTC
2014
Dec
9
22
2014
Nov
24
7
Wakkanai (Hokkaido, Japan)
2014
Oct
9
22
2014
Sep
24
2014
Aug
9
2014
Jul
0
2014
Jun
9
2014
May
11
0
2014
Apr
2
2014
Feb
11
2014
Mar
13
2
2014
Jan
4
2014
Dec
13
2014
Nov
15
4
2014
Oct
6
2014
Sep
15
2014
Aug
17
6
2014
Jul
8
2014
Jun
17
2014
May
19
8
2014
Apr
21
10
2014
Feb
12
19
2014
Mar
21
2014
Jan
12
10
JST
24
22
JST
UTC
IS-QZSS Ver. 1.6
Perth
Figure 4.2.1-1 Initial Single-satellite QZSS Visibility Time for eight Reference Locations. (See
Table 4.2.1-1 for calculation condition. Dark shaded areas represent elevation angles of
60[deg] or more; light blue areas represent elevation angles of 10[deg] to 60[deg] and white is
less than 10[deg]; vertical scale is hours on UTC and JST.)
38
IS-QZSS Ver. 1.6
4.3 System Performance
4.3.1 Availability
4.3.1.1 QZSS Availability in the case of a Single Satellite
With regard to the transmission of availability enhancement signals, QZSS availability (the percentage
of the normal use signal in visibility time (10 [degrees] elevation angle or higher)) in the case of a
single satellite shall be 95% or better.
With regard to the transmission of performance enhancement signals (L1-SAIF signal), availability
(the percentage of the normal use signal in visibility time (10 degrees elevation angle or higher) during
apogee ± 4 [hours] in the target region of performance enhancement experiment (same area shown in
Figure 4.1.5-1)) shall be 95% or better.
As to LEX signal, specific value on the availability is not defined during the demonstration phase.
4.3.1.2 QZSS Availability in the case of a 3-satellite constellation
TBD
4.3.2 Alert flag, URA, Health Data and Integrity Data
4.3.2.1 Notification of Alert flag, URA, Health Data and Integrity Data
In L1, L2 and L5 signals, data relating to the status of the QZS signals and other GNSS systems’
signals are sent to the user by means of the "Alert" flag, URA and health data. In the case of L1-SAIF
signal, Integrity Data Index (UDREI=User Differential Range Error Index) would be used.
"Alert" flag will set to "1" in the case that SIS accuracy exceeds 9.65 [m] or other troubles for QZS
happens (Default case: "Alert" flag="0").
4.3.2.2 Maximum Notification Times
The maximum notification times relating to URA, the "Alert" flag, and health data are defined as the
worst case (longest) time required from the moment of detecting anomaly by a QZSS Monitor Station
until the total notification message arrives at the user's antenna input terminal.
In the case of L1-SAIF signal, the maximum notification times relating to UDREI is defined as the
worst case (longest) time required from the moment of detecting anomaly by a L1-SAIF Master
Station until the total notification message arrives at the user's antenna input terminal through MCS.
Figure 4.3.2-1 shows the maximum notification times for "Alert" flag, URA, Health data and integrity
data.
4.3.2.3 False Alarm Probability
The probability that the "Alert" flag will be erroneously set to "1" (even though the corresponding
QZS signal is normal and can be used) shall be 1×10–6or less.
4.3.2.4 Miss-Detection Probability
The probability that the "Alert" flag will erroneously not be set to "1" (even though an error has
occurred with respect to the QZS signal and the signal should not be used) shall be 1×10–3 or less.
39
IS-QZSS Ver. 1.6
0
(Event Occurrence)
50
100
150
200
250
300
time
Alert
30s
60s
URA
L1C/A
Health (Subframe 1)
90s
Health (Subframe 4,5) ※
L1C
900s
Alert (L1C Health)
90s
URA
90s
Health ※
240s
Alert
40s
URA
L2C
70s
Health (MSG Type 10)
90s
Health (MSG Type 53) ※
Alert
240s
30s
URA
L5
60s
Health (MSG Type 10)
90s
Health (MSG Type 53) ※
L1-SAIF
LEX
240s
UDREI
24s
Alert
24s
URA
Health
400s
24s
※Target is the health information of Other GNSS systems
Figure 4.3.2-1 "Alert" flag, URA, Health Data and Integrity Data Maximum Notification Time
4.3.2.5 L1-SAIF Signal Specifications
The appropriate protection level* shall be computed within 30 [seconds] by user receivers at any
location in the service area even when an error condition occurs. The probability of the user
positioning error exceeding the protection level shall be 0.00001[/hour] or less.
*Protection level: Protection Level provides a bound on the position error with a probability derived
from the integrity requirement, in the case of L1-SAIF, 99.999%.
4.3.3 Accuracy
4.3.3.1 SIS Accuracy provided by QZSS Availability Enhancement Signals
The SIS accuracy provided by all QZS signals (except the L1-SAIF and LEX signals) shall be such
that the URA will not exceed 2.60 [m] with a probability of 95% or better including the error of the
time systems’ offset and the coordinate systems’ offset between QZSS and GPS.
4.3.3.2 Accuracy of Interoperability with Existing GNSS
4.3.3.2.1 Time System Offset
The QZSS time scale offset from GPS time shall not exceed 2.0 [m] (about 6.67 [ns]) with a
probability of 95% or better. The QZSS time scale offset from Galileo shall not exceed TBD [m]
(TBD [ns]) with a probability of 95% or better.
4.3.3.2.2 Coordinate System Offset
The QZSS coordinate system offset from GPS and Galileo shall be 0.02 [m] or less
40
IS-QZSS Ver. 1.6
4.3.3.3 Accuracy of Ionospheric Parameters
The accuracy available from the ionospheric parameters transmitted by the QZS shall be such that
user receivers in the regions indicated in Section 4.1.5 will be able to correct the associated range
measurements to within 14.0 [m] or better, with the exception of intervals during large ionospheric
disturbances (about 5% in a year).
4.3.3.4 Positioning Accuracy by means of Availability Enhancement Signals
The horizontal positioning accuracy shown in Table 4.3.3-1 shall be provided 95% of the time or more,
through QZS signals (except L1-SAIF and LEX signals) used in combination with GPS signals,
assuming all signals arrive at 10 degrees elevation angle or higher.
Table 4.3.3-1 Positioning Accuracy by means of Availability Enhancement Signals
Horizontal Positioning accuracy
Notes
Equivalent to modernized GPS signal (horizontal
positioning accuracy 95%)
Single frequency: 21.9 [m]
Dual frequency: 7.5 [m]
Single frequency (user ranging error: 7.3 [m])
Dual frequency (user ranging error: 2.5 [m])
4.3.3.5 Positioning Accuracy by means of Performance Enhancement Signals
The positioning accuracy shown in Table 4.3.3-2 shall be achievable with the QZSS L1-SAIF signal,
except in cases of large multipath error or a large ionospheric disturbance.
Table 4.3.3-2 Positioning Accuracy by means of Performance Enhancement Signals
Positioning accuracy
Notes
Submeter class: 1 [m] (RMS)
(wide-area DGPS performance enhancement)
L1-SAIF signal use
more than 5 [degree] elevation angle
41
IS-QZSS Ver. 1.6
5 QZSS Signal Properties
QZSS provides six types of signals to users.
Section 5.1 describes the fundamental properties of all QZS signals. Subsequent sections provide details
such as the signal configuration, carrier wave properties, code properties and navigation message
configuration and content for each of the six signals transmitted by QZS satellites.
5.1 QZS Power Levels, Bandwidths and Center Frequencies
All QZS signals are right-hand circularly polarized spread spectrum signals. Table 5.1-1
shows the center frequencies, bandwidths and received minimum power levels of these
signals.
After being superimposed with a navigation message, the baseband QZS signals are
modulated with a spread spectrum pseudorandom noise (PRN) code and then up-converted
by an RF carrier at the indicated center frequency.
Table 5.1-1 QZS signal specifications
Signal name
I/Q channel
identification
L1C/A
L1CA
Center frequency
Frequency
Bandwidth*1
24.0 [MHz]
(±12.0 [MHz])
L1CD
L1C
L2C
–
1227.60 [MHz]
–157.0 [dBW]
(Total)
24.0 [MHz]
(±12.0 [MHz])
–161.0 [dBW]
24.0 [MHz]
(±12.0 [MHz])
–160.0 [dBW]
(total)
24.9 [MHz]
(±12.45 [MHz])
–157.9 [dBW]
24.9 [MHz]
(±12.45 [MHz])
–157.9 [dBW]
39.0 [MHz]
(±19.5 [MHz])
–155.7 [dBW]
(total)
–154.9 [dBW]
(Total)
1176.45 [MHz]
L5Q
LEX
–158.5 [dBW]
–158.25 [dBW]
L5I
L5
–
Power
–163.0 [dBW]
L1CP
–
Received
24.0 [MHz]
(±12.0 [MHz])
1575.42 [MHz]
L1-SAIF
Minimum
Level*1,*2
1278.75 [MHz]
*1: Please note that the specifications are applied only to QZS-1.
*2: This is defined in Section 5.1.1.8.
42
IS-QZSS Ver. 1.6
5.1.1 Overview of signal properties
5.1.1.1 QZS Signal configuration
Table 5.1.1-1 shows a summary of the ranging code, modulation method and navigation message
structure for each of the QZS signals.
Table 5.1.1-1 Configuration of QZS signals
Signal name
(abbreviation)
L1C/A signal
(QZS-L1)
L1C signal
(QZS-L1C)
Channel
identification
–
L1CD
Ranging code and modulation method
Navigational message
One of the PRN codes* for the GPS C/A
signal in Applicable Document (1).
Modulation method is BPSK (Bi-Phase Shift
Key) (1).
Same data structure, bit rate and coding
method as the C/A signal in Applicable
Documentation (1) in Chapter 2; same
type of navigation message.
One of the PRN codes* for the GPS PRN
code specified in Applicable Document (3).
Modulation method of QZS-1 is BOC
(Binary Offset Carrier) (1, 1).
Same data structure, bit rate and coding
method
as
in
Applicable
Documentation (3) in Chapter 2; same
type of navigation message.
Modulated using the same code
sequence as the overlay code in
Applicable Documentation (3) in
Chapter 2.
Same data structure, bit rate and coding
method
as
in
Applicable
Documentation (4) in Chapter 2; same
type of navigation message.
Same type of Navigation message with
the same data structure, bit rate and
coding method as in Applicable
Document (1).
Dataless (i.e., no data is modulated onto
this
signal)
Same type of Navigation message with
the same data structure, bit rate and
coding method as in Applicable
Document (2).
Dataless
L1 signals
L1CP
L1-SAIF signal
(QZS-L1SAIF)
L2C signal
(QZS-L2C)
L5 signal (QZS-L5)
LEX signal
(QZS-LEX)
–
One of the PRN codes* for the GPS C/A
signal in Applicable Document (1).
Modulation method is BPSK (1).
–
One of the PRN codes* for
the GPS L2C signal in
Applicable
Document
(1). Modulation method is
BPSK (1).
L2C (CM)
code
L2C (CL)
code
I channel
One of the PRN codes* for the GPS L5 signal
in Applicable Document (2). Modulation
method is BPSK (10).
Q channel
One of the PRN codes for the GPS L5 signal
in Applicable Document (2). Modulation
method is BPSK (10).
Small Kasami sequence.
Short code
Modulation method is
BPSK (5).
2 channels are obtained by
chip by chip time
multiplexing.
Long code
–
2000 [bits/frame] At the beginning of the
frame, in addition to the preamble there
is a type ID that identifies the content
of the frame. 250 [sps] x 8 = 2 [kbps]
by means of code-shift keying. A ReedSolomon code is added.
Dataless
* According to applicable document (1), (2) and (3), the PRN codes were extended for the correspondence to GPS-III, but it have
not been supported by QZS-1 in the current MCS.
43
IS-QZSS Ver. 1.6
5.1.1.1.1 Signal configuration of L1 signals
QZS transmits three signals using the L1 center frequency: the L1C/A signal, the L1C signal and
the L1-SAIF signal.
The L1 availability enhancement signals include two carrier waves (L1C/A、L1CD and L1CP) that
are designed to maintain a specified phase relationship. The I-channel contains L1C/A and L1CD
while the orthogonal Q-channel contains L1CP. The phase relationship specifications are given in
Section 5.1.1.6.1.
L1C/A, L1CD and L1CP are BPSK modulated with bit strings equivalent to the L1C/A signal, the
L1C signal data channel, and the L1C signal pilot channel, respectively. When the L1CD modulation
bit of QZS-1 is "0", the phase of the L1CD carrier wave is 0°. The L1CD carrier wave is 180° reversed
when the L1CD modulation bit is "1". When the L1CP modulation bit is "1", the phase of the L1CP
carrier wave is 90° advanced. When the L1CP modulation bit is "0", the phase of the L1CP carrier
wave is 90° delayed.
The phase relation of LI signal for QZS-1 is not same as GPS-III (Refer to Applicable Documents
(3). L1CD and L1CP for QZS-1 are orthogonal each other at right angles, but L1CD and L1CP for GPSIII are in phase (Figure 5.1.1-1).
QZS-1
GPS-Ⅲ
L1CD、L1C/A
L1CP
L1CD、L1CP
L1C/A
Figure 5.1.1-1 Phase Relations of LI Signal for QZS-1 and GPS-III
(Counterclockwise rotation means phase leading of the signal. Each signal phase means
relative phase at modulation bit="0")
5.1.1.1.2 L2C signal configuration
The L2C signal has a single carrier wave. This carrier wave is BPSK modulated using a certain bit
string CL2C. This bit string is generated by two types of bit strings CL2CM, CL2CL (corresponding to
two channels) that are selected alternately in a time-multiplexed manner.
5.1.1.1.3 L5 signal configuration
The L5 signal has two carrier waves that are orthogonal with respect to one another. The phase
relationship specifications are given in Section 5.1.1.6.1.
Each of these carrier waves is BPSK modulated by two types of bit strings CL5I5, CL5Q5
(corresponding to the two channels). When the L5I modulation bit is "0", the phase of the L5I carrier
wave is 0°. The L5I carrier wave is 180° reversed when the L5I modulation bit is "1". When the L5Q
modulation bit is "1", the phase of the L5Q carrier wave is 90° advanced. When the L5Q modulation
bit is "0", the phase of the L5Q carrier wave is 90° delayed.
44
IS-QZSS Ver. 1.6
5.1.1.1.4 L1-SAIF signal configuration
The L1-SAIF signal has a single carrier wave. This carrier wave is BPSK modulated by a certain
bit string CL1SAIF.
5.1.1.1.5 LEX signal configuration
The LEX signal has a single carrier wave. This carrier wave is BPSK modulated by a certain bit
string CLEX. This bit string is generated by two types of bit strings CLEXS and CLEXL (corresponding
to two channels) that are selected alternately in a time-multiplexed manner.
5.1.1.2 QZS Operational Frequency
The operational QZS frequency, fs, is offset with respect to the reference frequency of f0 = 10.23
[MHz], in order to provide compensation for the relativistic effect to which the QZS satellites are
subjected due to their orbital motion. The frequency is as follows:

∆f 
 × f 0 = 1 − 5.399 × 10 −10 × 10230000 [Hz ] ≅ 10229999.994476823 [Hz ]
f s = 1 +
f0 

(
)
Since the QZS orbits are elliptical, the impact of the relativistic effect will slowly fluctuate. However,
the equations in Section 6.3.2 (2) can be used to compensate for this. In addition, the equations in
Section 6.3.2 (1) with the SV clock parameters (af0, af1, af2,) included in the QZSS navigation messages
can be used to compensate for the fluctuation of QZSST depended on other sources.
5.1.1.3 Correlation loss
Correlation loss is defined as the difference between the SV power received in the specified signal
bandwidth (e.g., ± 12 [MHz] for the L1 carrier) and the signal power recovered in an ideal receiver of
the same bandwidth, which perfectly correlates using an exact replica of the waveform within an ideal
(sharp cut-off) bandpass filter with linear phase. For all QZSS signals, the correlation loss that occurs
in the navigation payload of the QZS satellite shall not exceed 0.6 [dB].
5.1.1.4 Carrier phase noise
For all QZSS signals, the spectral density of the phase noise for the unmodulated carrier wave (i.e.,
prior to modulation with the PRN code and navigation message) shall be such that a phase-locked
loop (PLL) with single-sided bandwidth of 10 [Hz] will be able to track the carrier phase to an
accuracy of 0.1 [radians] (RMS).
Figure 5.1.1-2 shows the phase noise requirements for all QZSS signals in more detail.
Phase Noise Density (dBc/Hz)
0
-20
-40
-47
-47
-60
-77
-80
-94
-100
-101
-105
-110
-120
1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06
Offset Frequency (Hz)
Figure 5.1.1-2 Phase Noise of all QZS signals
5.1.1.5 Spurious characteristics
For all QZSS signals, in-band spurious transmissions shall be at least 40 [dB] below the power level
of the unmodulated carrier wave (i.e., prior to superposition of the PRN code and navigation message).
45
IS-QZSS Ver. 1.6
5.1.1.6 Phase relationships among QZS signals
5.1.1.6.1 Phase orthogonal
The two carrier waves (L1CD and L1CP, L5I and L5Q) are maintained in a 90° orthogonal phase
relationship with one another. The variation in this phase relationship shall not exceed ± 5.0°.
5.1.1.6.2 Phase relationship of PRN code and carrier wave
The fluctuations in the difference between the Pseudo Random Noise (PRN) code phase and the
carrier wave phase at the antenna phase center for all QZS signals shall not exceed 1.2 [ns].
Additionally, within any 30 [s] period, fluctuations in the difference between the PRN code phase
and the carrier wave phase shall not exceed 0.01 [ns] (equivalent to 0.3 [cm] ranging error).
5.1.1.6.3 PRN code jitter
5.1.1.6.3.1 PRN code jitter
The jitter, σjitter, of the PRN code zero-crossing interval (according to Figure 5.1.1-3) shall not
exceed 2.0 [ns] for a value of 3σ.
Complete, ideal PRN code
Realistic PRN code with edge jitter
σjitter
σjitter
σjitter
σjitter
σjitter
σjitter
σjitter
Figure 5.1.1-3 Definition of code jitter σjitter
5.1.1.6.3.2 Delay in PRN code rising/falling edge
For the PRN code, the mean value for the rising edge delay time (or advance time), Δ, (as
illustrated in Figure 5.1.1-4) when the falling edge is viewed to be correct shall not exceed 1.0
[ns].
Complete PRN code
PRN code with late falling edge
Δ
Δ
Δ
PRN code with late rising edge
Δ
Δ
Δ
Δ
Figure 5.1.1-4 Definition of delay time, Δ, for PRN code rising/falling edge
46
IS-QZSS Ver. 1.6
5.1.1.7 PRN code phase relationships among signals
All QZS signals are generated from the same single clock with the operational frequency indicated in
Section 5.1.1.2.
The PRN code phase differences between QZS signals at the antenna phase center shall not exceed
the values shown in Table 5.1.1-2.
Table 5.1.1-2 Differences in Pseudo Random Noise (PRN) code phases among QZS signals
L2
LEX
L5
25 ns
35 ns
20 ns
L1
15 ns
10 ns
L2
20 ns
LEX
The fluctuations in phase difference shall not exceed 2 ns for a value of 3σ.
Within any 30 [s] period, QZS phase differences shall not exceed 0.01 [ns] ( ≈ 0.3 [cm]).
These phase differences are included in navigation messages (TGD, ISC (Inter-Signal Correction), etc.)
and transmitted to users. The accuracy is 4.5 [ns] (3-sigma) for TGD, and 3.0 [ns] (3-sigma) for ISC.
47
IS-QZSS Ver. 1.6
5.1.1.8 Minimum received power level
A ground-based isotropic antenna with a gain of 0 [dBi] for circularly polarized wave reception is
provided and, when QZS signals are received from a Quasi Zenith Satellite (QZS) with an elevation
angle of 10° or more, the reception power must not be lower than the value indicated in Table 5.1-1.
In general, the reception power in each part of the service area is as shown in Section 3.1.3.6.
5.1.1.9 Polarization characteristics
All QZS signals are right-hand circularly polarized. The axial ratio (power ratio of the long axis to
short axis) of the QZS circularly polarized waves, in the beam range of ± 10° from the boresight
direction, shall not exceed 1.0 [dB] for the L1 signals and 2.0 [dB] for the L2, LEX and L5 signals.
The axial ratio of the L1-SAIF signal is less than 1.0 [dB].
5.1.1.10 Antenna Phase Center Characteristics
For all QZS signals with the exception of the L1-SAIF signal, the antenna phase center of the L-ANT
is in the range of ± 1 [cm] in the beam range of ±10 [deg] from the direction of the L-ANT boresight.
The L1-SAIF signal is transmitted from another antenna, LS-ANT. And the antenna phase center of
the LS-ANT is in the range of ± 1 [cm] from the direction of the boresight.
Because the L1-SAIF signal is transmitted from the other antenna, the ephemeris data of L1-SAIF
signal is not same as the ephemeris of the other signals, such as L1 C/A signal, L1C signal, L2C signal
and L5 signal.
5.1.1.11 PRN Code Numbers
5.1.1.11.1 Availability Enhancement Signals
QZSS uses the same type of PRN code as GPS. Detailed information are referenced in the sections
starting with 5.2 and in Applicable Documents (1), (2) and (3). The PRN code numbers used by QZSS
are 193-197. The initial QZS is assigned code number 193, and the second and succeeding QZS are
assigned numbers in sequence starting with 194. PRN code numbers 198–202 are used for QZS
maintenance/test purposes and must not be used by users.
5.1.1.11.2 Performance Enhancement Signals
(1) L1-SAIF signal
A PRN code of the same type as the GPS L1C/A signal is used. For more information 3 are
referenced in the Applicable Documents (1). The PRN code numbers are 183–187. The initial
QZS is assigned code number 183, and the second and succeeding QZS are assigned numbers
in sequence starting with 184. PRN code numbers 188–192 are used for QZS maintenance/test
purposes and must not be used by users.
(2) LEX Signal
A small Kasami series is used. For more information, see Section 5.7. The numbers are 193 ~
197. The initial QZS is assigned number 193, and the second and succeeding QZS are assigned
numbers in sequence starting with 194. Numbers 198 ~ 202 are used for QZS maintenance/test
purposes and must not be used by users.
3 The allowance of PRN Code is approved by GPSW through the process defined by “PSEUDO RANDOM (PRN) CODE
ASSIGNMENT PROCESS” (GLOBAL POSTIONING SYSTEMS WING (GPSW), 1 February 2007). (The allowance of LIC signal
will be approved officially after the IS-GPS-800 is established and the revision of above document is completed. The allowance of
LIC for QZSS has been agreed at the GPS-QZSS TWG.)
48
IS-QZSS Ver. 1.6
5.1.2 Navigational messages
5.1.2.1 Content of Navigation Messages
QZSS superimposes onto the PRN code data to aid identification of QZS position as well as other
data described in the following subsections. As is typical of other GNSS systems, QZS transmits this
information in the form of navigation messages. The content of the major QZSS navigation messages
is shown below. For detailed information regarding the navigation messages broadcast on each QZSS
signal, see the sections beginning with 5.2.
5.1.2.1.1 Ephemeris Data and SV Clock Parameters
QZSS provides users with Ephemeris data and SV clock parameters referenced to the QZS antenna
phase center. These are available for positioning calculations on the part of users.
5.1.2.1.2 Almanac Data
QZSS provides Almanac data referenced to the QZS antenna phase center. These data are available
for satellite selection calculations and Doppler calculations by users.
5.1.2.1.3 URA, Health Data
QZSS provides users with the URA and Health data (in case of L1C/A) shown in Figure 5.1.2-1.
The latest health status for navigation signals and QZS-1 itself are posted on QZS-1 user website
"QZ-vision" as the experimental schedule (see section 7.2.2) and NAQU information (see section
7.2.1).
1 bit
Subframe 1
Ephemeris Health
Summa
ry
＋Other
malfunc
tion
1 bit health
5 bits
4 bits
URA Index
Accuracy
RF Signal
Strength Status
Navigation
Message Status
Subframe 4,5
Almanac Health
3 bits
3 bits health
Summary
＋Other malfunction
5 bits
5 bits health
Satellite Health
1 bit health
1 bit
5 bits
Figure 5.1.2-1 QZS URA and Health Data on L1C/A signal
5.1.2.1.3.1 "Alert" Flag
The "Alert" flag is transmitted by bit 18 in the second word (HOW) of all subframes of the L1C/A
signal, by bit 38 of all message types of the L2C and L5 signals, and by bit 33 of subframe 2 of
the L1C signal (the section named "L1C Signal Health" in Applicable Document (3)).
When the ALERT flag is set to "1", this indicates that the SIS accuracy of the corresponding QZS
signal is worse than 9.65 [m], or that an error of some kind has occurred on the QZS such that the
specified accuracy cannot be guaranteed. Note that 9.65 [m] corresponds to the upper limit for
the NMCT correction indicated in Section 5.2.2.2.5.2 (8).
The operating concept for the ALERT flag is discussed in Section 3.1.2.1.3.
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IS-QZSS Ver. 1.6
QZSS constantly monitors the SIS error of the QZS signal and the status of the QZS and transmits
the data to the user within the seconds, which is specified in Section 4.3.2.2 after an error has
occurred. In such cases, use of the corresponding signal is not advised, however, users may do so
at their own risk.
5.1.2.1.3.2 URA, URAED, URANED
URA index are transmitted by subframe 1 of the L1C/A signal, URAED (=Elevation-dependent
(ED) component User Range Accuracy) index are transmitted by message type 10 of the L2C and
L5 signals, and subframe 2 of the L1C signal, and URANED (=Non-Elevation-Dependent (NED)
component User Range Accuracy) index are transmitted by message type 30, 31, 32, 33, 34, 35,
37, 46, 49, 51 and 53 of the L2C and L5 signals and subframe 2 of the L1C signal.
These are related to the SIS error of the corresponding signal. Regardless of whether the "Alert"
flag is set to "0" or "1", QZSS ensures that the current SIS error of the corresponding signal does
not exceed the value expressed by URA, URAED and URANED. The probability that instantaneous
URE (User Range Error) becomes greater than 5.73×URA is less than 1×10–8 [1/h].
The algorithm used to determine the value of URA, URAED and URANED from URA index,
URAED index and URANED index is the same as that in Applicable Documents (1), (2) and (3).
QZSS constantly monitors the SIS error of all QZS signals. The URA parameters are transmitted
for use as reference data. When the URA parameters indicate poor accuracy (in the case of the
URA index="15" or URAED index and URANED index = "15" or "–16"), use of the corresponding
signal is not advised, however, users may do so at their own risk.
5.1.2.1.3.3 5-bit Health
The 5-bit health word is transmitted by the last 5 bits of the Ephemeris health [Section
5.2.2.2.3(4)] included in subframe 1 of the L1C/A signal, and the last 5 bits of the Almanac health
[Section 5.2.2.2.5.2(2)(b)] and satellite health [Section 5.2.2.2.5.2(3)] included in subframes 4
and 5.
The data included in the 5-bit health relate to the signal health of the satellite, such as L1 C/A
signal, L2C signal, L5 signal, L1C signal and LEX signal. Each bit is set to "0" when the signal
at the satellite is broadcasted correctly and available, and is set to "1" when the health of each
signal is bad. The definition of the bit allocation is shown in the Table 5.1.2-1.
For GPS satellites, if the signal is not broadcasted or the status of the signal is unhealthy (judged
by MCS), the 1 bit health of the signal is set to "1".
In the case of the 1bit health="1", the signal of the satellite should be used at the user’s own risk.
Table 5.1.2-1 Details of Health (5-bit health) code for all QZSS signals
Bit Allocation
QZS Health
GPS Health
Notes
Bit 1 (MSB)
Health of L1C/A signal
Health of L1C/A signal
Bit 2
Health of L2C signal
Health of L2C signal
Bit 3
Health of L5 signal
Health of L5 signal
Bit 4
Health of L1C signal
Health of L1C signal
Bit 5 (LSB)
Health of LEX signal
reserved
50
Set "1" when GPS
IS-QZSS Ver. 1.6
5.1.2.1.3.4 3-bit health and 1-bit health
The 3-bit health word is transmitted by the first 3 bits of the Almanac Health [5.2.2.2.5.2(2)(b)]
included in subframe 4 and 5 of the L1C/A signal.
The 1-bit health word is transmitted by the first bit of the Ephemeris Health [5.2.2.2.3(4)] included
in subframe 1 of the L1C/A signal, by the first bit of the Satellite Health [5.2.2.2.5.2(3)] included
in subframe 4 and 5, by "L1 Health", "L2 Health" and "L5 Health" in message type 10, 12, 31
and 37 in the L2C and L5 signals, and by "L1 Health", "L2 Health" and "L5 Health" on pages 3
and 4 in subframe 3 of the L1C signal.
These Health bits indicate the status of the Navigation Message for the QZS signal transmitted
by the associated satellite. The definition of the 3-bit Health word is the same as in Section
20.3.3.5.1.3 in Applicable Document (1). The 1-bit Health is set to "1" in the event that there is
an error with any one or more of the following: the Navigation Message, power level, modulation,
etc.
QZSS constantly monitors the status of not only the QZS but also other satellite positioning
systems including GPS. The MCS judges whether the system is in normal or error status and then
generates these bits accordingly and provides the data to the user within the seconds, which is
specified in Section 4.3.2.2. For all codes other than that corresponding to "All Signals OK", users
are cautioned to only use the associated signal at their own risk.
5.1.2.2 Timing of subframes, pages and data sets
5.1.2.2.1 IODE, IODC
The IODE (Issue of Data, Ephemeris) in the same data set has the same 8 bits as the 8 LSBs of the
10-bit IODC (Issue of Data, Clock). (In other words, if the last 8 bits of IODE and IODC are the
same, these constitute the same data set.)
For transmissions of IODE and IODC for different data sets, the following rules apply:
(1) The transmitted IODC is different from the value transmitted from the satellite for the
previous two days.
(2) The transmitted IODE is different from the value transmitted from the satellite for the
previous six hours.
5.1.2.2.2 Relationship between epoch data and data set update
The epoch for Ephemeris data that possesses a new data set is assured to be different from that
transmitted prior to updating.
5.1.2.2.3 Data set update
With the exception of the first data set after service is resumed following orbit maintenance and
attitude maintenance (as described in Section 3.1.2.2.1.1 and 3.1.2.2.1.2, respectively), the data set
is updated at the boundary of whole number hours.
The initial data set may be updated to a new data set at any time, even during the effective period
for that data set. The beginning of the transmission interval for each data set is the same: the
beginning of the effective period for the data set. The data set is valid for the duration which the
curve fit interval flag means (see section 5.2.2.2.4 (4)).
In the process of updating the shortest data set, the data sets in subframes 1, 2 and 3 in the L1C/A
signal, in message type 10 and 11 in L2C and L5 signals, and in subframe 2 in the L1C signal are
updated once per hour. The corresponding effective period is 2 hours (at minimum).
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IS-QZSS Ver. 1.6
5.1.2.2.4 Data set update at the end-of-week crossover
At the end-of-week crossover, the L1C/A signal transmission starts again from subframe 1. In
addition, the subframe 4 and 5 cycles that are dependent on the data set start again at the end-ofweek crossover, regardless of what pages were transmitted prior to the end-of-week crossover.
The L2C and L5 signals start again from message type 10 at the end-of-week crossover. The cycles
for message types that are dependent on the data set start again at the end-of-week crossover,
regardless of what message types were transmitted prior to the crossover.
With the L1C signal, at the end of week crossover, the cycles for message types that are dependent
on the data set start again at the end of week crossover, regardless of what message types were
transmitted prior to the crossover.
5.1.2.2.5 toe and toc
The toe shall be equal to the toc of the same data set (same as Applicable document (1), (2) and (3)).
The following rules govern the transmission of toe and toc values in different data sets:
(1) The transmitted toc will be different from any value transmitted by the SV during the
preceding seven days.
(2) The transmitted toe will be different from any value transmitted by the SV during the
preceding six hours.
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IS-QZSS Ver. 1.6
5.2 L1C/A signal
5.2.1 RF characteristics
5.2.1.1 Signal configuration
In accordance with Section 5.1.
5.2.1.2 Carrier wave properties
In accordance with Section 5.1.
5.2.1.3 Code properties
5.2.1.3.1 Code attributes
Almost same as in Sections 3.2.1.3 and 3.3.2.3 of Applicable Document (1), but the extensions of
the PRN codes and the PRN code numbers for GPS-III have not been supported by QZS-1 in current
MCS. In addition, the PRN code numbers for QZSS are as described in Section 5.1.1.11.1 of this
document.
5.2.1.3.2 Non-Standard Code (NSC)
In the event that a problem with the satellite or the ground-based system occurs, a non-standard
code (NSC) is transmitted. This is done to protect users by ensuring that they do not receive or use
erroneous navigation data.
5.2.2 Messages
5.2.2.1 Message configuration
Each word is made up of 30 bits. Ten words make up one subframe. Five subframes make up one loop.
This message configuration is the same as in Applicable Document (1).
5.2.2.1.1 Preamble
The 8-bit preamble added to the beginning of the 10 words of the subframe is the same as in Section
20.3.3.1 of Applicable Document (1).
5.2.2.1.2 Parity algorithm
The 6-bit parity bits are added to the end of the 30-bit word is the same (32, 26) Hamming Code as
specified in Section 20.3.5.1 of Applicable Document (1).
5.2.2.1.3 Parity Check algorithm
See section 20.3.5.2 of Applicable Document (1).
5.2.2.2 Message content
5.2.2.2.1 Telemetry word (1st word)
This word is used for QZSS maintenance/test purposes.
Bits 23 of each TLM word in GPS L1C/A signal is defined as "Integrity Status Flag" (Refer to
Applicable Document (1) Section 20.3.3.1). But QZS-1 does not adopt this Flag (Fixed at "0"(B)).
5.2.2.2.2 Handover word (HOW) (2nd word)
With the exception of the following, same as 20.3.3.2 in Applicable Document (1).
For information on the use of the "Alert" flag in bit 18, see Section 3.1.2.1.3. For information on
the content of the "Alert" flag, see Section 5.1.2.1.3.
The Anti-Spoof flag (A-S), bit 19, is "0"(B) indicating that the QZSS is in non-A-S mode.
53
IS-QZSS Ver. 1.6
5.2.2.2.3 Subframe 1
Subframe 1 includes the clock data, etc. for the corresponding satellite. For more information
regarding the general content of subframe 1, see Section 20.3.3.3.1 in Applicable Document (1).
The parameter characteristics of Subframe 1 (number of bits, LSB scale factor, range, unit, data
structure (page format etc.) etc.) are the same as in Section 20.3.3.3.2 in Applicable Document (1).
(1) Transmission Week Number
Same as 20.3.3.3.1.1 in Applicable Document (1).
Transmission Week Number is described with the ten bits data (0–1024). These ten bits shall
be a modulo 1024 binary representation of the current GPS week number at the start of the data
set transmission interval (originally zero epoch was set at 00:00:00 (UTC) on 6 Jan., 1980).
The week count is known that it will roll over every 1024 week. The current epoch of GPS
week number (as of April, 2014) is 22 Aug., 1999 and next rollover comes on 7 Apr., 2019.
(2) L2 channel code
Bits 11 and 12 (L2 channel code) in word 3 are fixed at "10"(B).
(3) Satellite User Ranging Accuracy Index: URA Index
Bits 13–16 in word 3 constitute the URA index. The algorithm signified by this URA index that
is used to determine the specific user positioning accuracy for the satellite is the same as in
Section 20.3.3.3.1.3 in Applicable Document (1).
For more information about how to use the URA index, see Section 3.1.2.1.3. For more
information about the content of URA, see Section 5.1.2.1.3.
(4) Health Data for the Satellite (Ephemeris Health)
Bits 17–22 in word 3 constitute the health of the corresponding QZS.
For more information on how to use the Ephemeris health, see Section 3.1.2.1.3.
Health data (Almanac Health and Satellite Health) are also present in Subframe 4 & 5, but the
refresh cycle for the Health data in Subframe 1 is more rapid, so the data are not identical.
(a) Summary of Navigation Message status for signals transmitted by the corresponding QZS
(1-bit health)
Bit 17 in word 3 shows a summary of the navigation message. The definition is in accordance
with Section 20.3.3.3.1.4 in Applicable Document (1).
(b) Status of signals transmitted by the corresponding QZS (5-bit Health)
Bits 18–22 in word 3 indicate the status of the signals transmitted by the corresponding QZS.
The definition is in accordance with Table 5.1.2-1.
(5) Issue of Data, Clock (IODC)
Bits 23 and 24 in word 3 indicate the 2 MSBs of the 10-bit IODC. Bits 1 ~ 8 in word 8 indicate
the 8 bits beginning with LSB in the IODC. IODC shows issuance number of data set. Users
can detect the update of data set by the time series behavior of IODC.
IODC is changed each time the SV Clock parameters (af0, af1, af2 etc.) are updated. The shortest
update period is every 900 seconds. For more information regarding IODC changes, etc., see
Section 5.1.2.2.
(6) Data flag for L2P code
As there is no L2P code, bit 1 in word 4 is fixed at "1"(B).
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IS-QZSS Ver. 1.6
(7) Internal signal group delay differential correction parameter
Bits 17 ~ 24 in word 7 indicate the internal signal group delay differential correction parameter
TGD for users who use only the L1C/A or only the L2C signal. For the definition and user
algorithm, see Section 6.3.3 and 6.3.4.
In the case of QZS-1 at current MCS, Bit string of TGD ="10000000"(B) indicates that the group
delay differential correction parameter (TGD) cannot be used. (This issue is not described in the
definition in Applicable Document (1).)
(8) SV Clock parameters
For information regarding the SV Clock parameters (toc, af2, af1 and af0) needed for users to
correct the SV clock offset, see Section 20.3.3.3.1.8 in Applicable Document (1). The user
algorithm is described in Section 6.3.2.
5.2.2.2.4 Subframe 2 & 3
Subframe 2 and 3 contain the Ephemeris data, etc., for the corresponding satellite. For more
information on the general content, see Section 20.3.3.4.1 in Applicable Document (1).
The parameter characteristics of Subframe 2 and 3 (number of bits, LSB scale factor, range, unit,
sub-commutation, etc.) are the same as in Section 20.3.3.4.2 in Applicable Document (1).
(1) AODO = NMCT (Navigation Message Correction Table) effective time
Bits 288 ~ 292 of subframe 2 constitute the effective time for the NMCT (navigation message
correction table). The parameter characteristics of Subframe 2 and 3 (number of bits, LSB scale
factor, range, unit, data structure (page format etc.), etc.) is the same as in Section 20.3.3.4.2 of
Applicable Document (1). The certain part of the user algorithm is not same as in Section
20.3.3.4.4 of Applicable Document (1).
When AODO is a binary value of "11111", NMCT cannot be used. This is also the same as in
Section 20.3.3.4.4 of Applicable Document (1).
The NMCT is transmitted from different QZS at different timings. Among these NMCT, the
most recent NMCT is the one with the largest tnmct value calculated using following equations.
tnmct = toe – AODO
Note: tnmct must account for the beginning or end of week crossover in following equations.
if t ∗ − t nmct > 302 ,400 then t nmct = t nmct + 604 ,800
if t ∗ − t nmct < −302 ,400 then t nmct = t nmct − 604 ,800
toe : Reference time Ephemeris (seconds into week) of the AODO broadcasting satellite [s]
t* : User receiver time (in GPST)
If calculated tnmct is larger than User receiver time t*, NMCT is available, and otherwise, NMCT
is not available. In addition, to respond the crossovers by ephemeris updates, if the difference
between t* and the ephemeris update time (for GPS: toe-7200[s]) is within a few minutes (for
GPS: the difference between toe and t* is larger than 6720 [s]), ERD (Estimated Range
Deviation) should not be used. In addition, QZS-1 at current MCS does not transmit effective
ERD for QZS-1 itself. (Invalid data (="100000"(B)) is transmitted.)
55
IS-QZSS Ver. 1.6
(
)
if t nmct − t ∗ > 0,
(
if t oe
target
else,
else, NOT valid
t oe
target
)
− t ∗ > 6720 [s ], NOT valid
ERDs are VALID
: Reference time ephemeris for the target satellite to correct
(2) Issue of Data, Ephemeris (IODE)
Bits 61 ~ 68 of subframe 2 and bits 271 ~ 278 of subframe 3 constitute the IODE. The meaning
of IODE is the same as in Section 20.3.4.4 of Applicable Document (1).
IODE changes each time the Ephemeris data (a, e, i and the other 6 orbital elements and CIC,
CIS and other correction parameters) are updated. The shortest update period is 15 minutes. For
more information on the use of IODE changes, etc., see Section 5.1.2.2.
(3) Ephemeris data
The Ephemeris data defined in Section 20.3.3.4.1 of Applicable Document (1) are transmitted
by subframe 2 and 3. However the range of eccentricity is restricted in GPS (max. 0.03), it is
not restricted in QZSS (less than 0.5). The user algorithm described in Section 6.3.5.
(4) Fit interval flag:
Effective time flag for Ephemeris data
Bit 17 in word 10 of subframe 2 is the fit interval flag.
When the curve fit interval flag is set to "0"(B), the Ephemeris data are effective for 2 hours
from data updated time. When the curve fit interval flag is "1"(B), the Ephemeris data are
effective for more than 2 hours.
5.2.2.2.5 Subframe 4 & 5
Subframes 4 and 5 include the Almanac data, Almanac Reference Week Number, Coordinated
Universal Time (UTC) parameter, Ionosphere parameter, NMCT, etc.
The parameter characteristics of subframes 4 and 5 (number of bits, LSB scale factor, range, unit,
data structure (page format etc.) etc.) are the same as in Section 20.3.3.5.1 of Applicable Document
(1).
Unlike GPS legacy navigation message in Applicable Document (1), 25 pages for QZSS do not
necessarily constitute one data set. The content of the transmitted data can be identified using the
SV ID and the data ID. For instance, the data set can be extended to 30 pages or more to send several
GNSS system parameters by using this flexible page concept.
5.2.2.2.5.1 Subframe 4 & 5 content identification
(1) Data identification
The content of Subframes 4 and 5 can be distinguished by means of the data ID in bits 61 ~ 62
and the Space Vehicle (SV) ID in bits 63 ~ 68. The data ID identifies the type of satellite
positioning system (for example, GPS, QZSS, etc.). The SV ID identifies the Space Vehicle
Number of the satellite and other information (for example, whether the data constitute an
ionospheric parameter, NMCT, etc.). The method used for identification is shown in Table
5.2.2-1. Moreover, GPS page number and the reference of data structure (figure number in
applicable document (1)) corresponding to the broadcasted Data-ID and SV-ID is summarized
in table 5.2.2-2. In addition, Space Vehicle Number is extended for GPS-III with Data
ID="10"(B) in the applicable document (1), but it would not be supported by QZS-1 at current
MCS.
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IS-QZSS Ver. 1.6
Table 5.2.2-1 Content identification using Data ID and Space Vehicle ID
Data ID=01(b), 10(b)
(Spare)
Data ID = 00 (b) (GPS)
SV ID
00(d)
Dummy satellite
01-32(d) GPS satellite Almanac
33-48(d)
49(d)
Spare
50(d)
GPS satellite Almanac Reference
Week Number, Almanac reference
time and Satellite Health data of
GPS satellite (PRN=1-24)
51(d)
52(d)
Sapre
53(d)
Spare
54(d)
55(d)
56(d)
GPS ionospheric parameters and
relationship between UTC (USNO)
and GPST
57(d)
58(d)
59(d)
60(d)
61(d)
62(d)
Spare
63(d)
A-S flag and Satellite Configuration of
GPS Satellite (PRN=1-32) and
Satellite Health data of GPS satellite
(PRN=25-32)
Data ID=11(b) (QZSS)
Dummy satellite
QZS almanac
Spare
GPS satellite Almanac Reference
Week Number, Almanac reference
time and Satellite Health data of
GPS satellite (PRN=1-24)
GPS satellite Almanac Reference
Week Number, Almanac reference
time and Satellite Health data of
GPS satellite (PRN=25-32)
QZS Almanac Reference Week
Number, Almanac reference time
and Satellite Health data of QZS
(PRN=193-197)
Navigation Message Correction
Table (NMCT) for GPS satellite
(PRN=1-30)
Navigation Message Correction
Table (NMCT) for QZS (PRN=193197) and GPS satellite
(PRN=31,32)
Navigation Message Correction
Table (NMCT) for Spare satellite
Special message
Ionospheric parameters especially
for Japan and relationship between
UTC (NICT) and GPST
Spare
Table 5.2.2-2 GPS page number and the reference of data structure corresponding to the
broadcasted Data-ID and SV-ID
01-32
DataID(b)
00, 11
49, 50
51
52-54
55
56
63
11
00, 11
11
11
00, 11
00
SV-ID(d)
Contents
See
Table5.2.2-1
Corresponding GPS message
Subframe No.
Page No.
(SF4) 2-5, 7-10
Figure20-1 ( 4/11)
4, 5
(SF5) 1-24
Figure20-1 ( 5/11)
5
25
Data Format*
Figure20-1
Figure20-1
Figure20-1
Figure20-1
(10/11)
(11/11)
( 8/11)
( 9/11)
4
4
4
4
* Data format means the reference of data structure (figure number in applicable document (1))
13
17
18
25
(2) Data transmission intervals
Data transmission intervals are depended upon Message pattern table (See Section 7.2.4.3)
57
IS-QZSS Ver. 1.6
5.2.2.2.5.2 Content of subframes 4 & 5
(1) Dummy data
When the SV ID is 0, it indicates the SV is dummy. In this case, the content comprises dummy
data (alternating values of "1"(B) and "0"(B) beginning with "1"(B)).
(2) Almanac data and Almanac health
When the SV ID is a value between 1 and 32, the content of that subframe comprises Almanac
data and Almanac health.
When the Data-ID is "11"(B), the content is QZS Almanac data and Almanac health, and the
eight bits of "data ID (2 bits) + SV ID (6 bits)" indicates the PRN number of the QZS.
When the Data-ID is "00"(B), the content is Almanac data and Almanac health for a GPS satellite
that is visible (or has the potential to be visible) in at least the area shown in Section 4.1.1.In
the case of the SV ID = 1 ~ 32, SV ID means the PRN code number of GPS satellites*. In the
case that one of the GPS satellite does not broadcast almanac data, Almanac health for that SV
is set "1" for all bits (="11111111"(B)) and Almanac data contains dummy data (alternating ones
and zeros beginning with ones).
Moreover, the structure of the message is shown in Table 5.2.2-2.
* According to the applicable document, PRN code numbers for GPS satellites would be
extended from 1 ~ 32 to 1 ~ 64, but it would not be supported by QZS-1 at current MCS.
Therefore GPS satellites’ data at PRN 33-64 would not be retransmitted by QZS-1 at current
MCS.
(a) Almanac data
Almanac data are entered in the sections of word 5 that do not include bits 17 ~ 24.
The parameter characteristics (number of bits, LSB scale factor, unit etc.) of Almanac data is
the same as in Section 20.3.3.5.1.2 of Applicable Document (1). The Almanac reference time
(toa) is referenced to the almanac reference week (WNa) (same as applicable document (1)).
In the case of QZSS, the eccentricity (e) means offset from 0.06 and the reference value of
the inclination (iref) is 0.25 [semi circles], which is different from the GPS definition (for GPS,
e means the eccentricity value itself and iref is 0.3 [semi circles]). In the case that one of the
GPS satellite does not broadcast almanac data, Almanac data correspond to that SV contains
dummy data (alternating ones and zeros beginning with ones).
The Almanac data for the QZS are updated at least once every 6 days. The velocity calculated
by the Almanac data is accurate within 30 [m/s]
The GPS Almanac data are GPS satellites’ Almanac data gathered by the QZSS Monitor
Stations.
The user algorithm is described in Section 6.3.6.
(b) Almanac Health
Almanac health is transmitted at the same time as Almanac data and is entered from bit 1724 of word 5.
This 8-bit Almanac health is divided into the first 3 bits and the last 5 bits. Definitions of the
first 3 bits are as shown in Section 5.1.2.1.3.4. The last 5 bits are as shown in Section
5.1.2.1.3.3.
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IS-QZSS Ver. 1.6
The QZSS Master Control Station (MCS) constantly monitors the status of not only the QZS
satellites but also other satellite positioning systems including GPS. The MCS makes
judgments regarding normal or error status and generates Almanac health data, and provides
these data to the user as reference data within the seconds, which is specified in Section
4.3.2.2. When Almanac data for one of the GPS satellite is dummy data, Almanac health
correspond to that SV is set "1" for all bits (="11111111"(B)). In this case, user shall use that
SV at his own risk.
(3) Satellite Health
When the Data-ID="00"(B) and the SV-ID= 51, 63, and when the Data-ID="11"(B) and the SVID= 49, 50, 51, the content of that subframe indicates the satellite health. Satellite health
comprises 6 bits for each satellite. The satellite health for multiple satellites is included in the
subframe. This 6 bits satellite health is divided into the first 1 bit and last 5 bits. The definition
of the first 1-bit health is shown in section 5.1.2.1.3.4, and the definition of the last 5-bits
health is shown in section 5.1.2.1.3.3. The structure of the message is shown in Table 5.2.2-2.
The format of the subframe is defined as same as the one defined in Applicable Document
(1), and the sequence in the subframe is shown in Table 5.2.2-3.
Table 5.2.2-3 Sequence of Satellite Health in the frame when Data-ID="11"(B)
Satellite Health
Area
SV1
SV2
SV3
SV4
SV5
SV6
SV7
SV8
SV9
SV10
SV11
SV12
SV13
SV14
SV15
SV16
SV17
SV18
SV19
SV20
SV21
SV22
SV23
SV24
Data-ID="11" (B)
SV-ID=49
GPS PRN1
GPS PRN2
GPS PRN3
GPS PRN4
GPS PRN5
GPS PRN6
GPS PRN7
GPS PRN8
GPS PRN9
GPS PRN10
GPS PRN11
GPS PRN12
GPS PRN13
GPS PRN14
GPS PRN15
GPS PRN16
GPS PRN17
GPS PRN18
GPS PRN19
GPS PRN20
GPS PRN21
GPS PRN22
GPS PRN23
GPS PRN24
Data-ID="11" (B)
SV-ID=50
GPS PRN25
GPS PRN26
GPS PRN27
GPS PRN28
GPS PRN29
GPS PRN30
GPS PRN31
GPS PRN32
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Data-ID="11" (B)
SV-ID=51
QZS PRN193
QZS PRN194
QZS PRN195
QZS PRN196
QZS PRN197
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
When the SV-ID= 51 and the Data-ID="11"(B), it indicates the QZS satellite health.
When the SV-ID= 49 or 50 and the Data-ID="11"(B), it indicates the health of GPS satellites as
judged by QZSS monitoring stations. The 24 MSBs of words 4 through 9 provide the satellite
health status for 24 satellites to users.
When the SV-ID= 51 and the Data-ID="00"(B), the contents is the same as the message in the
case of SV-ID= 49 and Data-ID="11"(B). Therefore the combination of SV-ID= 51 and DataID="00"(B) won’t be used in future.
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IS-QZSS Ver. 1.6
When the SV-ID= 63 and the Data-ID="00"(B), the contents are A-S flag and Satellite health
flag for GPS satellites (PRN25-32). The structure of the message is same as that in Figure 201 (Sheet 9 of 11) of Applicable Document (1). Since the satellite health data for GPS satellites
(PRN 25-32) are also included in the message of SV-ID= 51 and Data-ID="11"(B), the
combination of SV-ID= 63 and Data-ID="00"(B) won’t be used in future.
Additional SV Health data are also provided in subframe 1. The data for QZS-1 provided by
means of subframes 1, 4 and/or 5 are uploaded at a different time, so the data given in
subframe 1 may differ from the data in subframes 4 and 5. Besides, the SV Health data for other
SVs shown in subframe 4 and/or 5 of QZS-1 may also differ from the data given in subframes
1, 4, and 5 of the other SVs since the latter may be updated at a different time.
The current MCS of QZS-1 constantly monitors the status of not only the QZS-1 but other
satellite positioning systems including GPS. The MCS judges whether the system is in normal
or error status and then generates satellite health data and provides the data to the user within
the seconds, which is specified in Section 4.3.2.2 for use as reference data. In addition, in the
SV data for other SVs shown in subframe 4 and 5 of QZS-1, even if the SV Health data shows
that satellite "healthy", Almanac Health data of a satellite broadcasted by the satellite may
indicate "unhealthy" (="11111111"(B)). In this case, user shall use that SV at his own risk.
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IS-QZSS Ver. 1.6
(4) Anti-Spoof flag and satellite configuration
When the SV ID is 63 and the Data-ID is "00"(B), a 4-bit code (capacity for 32 items) is provided,
indicating the GPS A-S status and configuration. This code is the same as in Section
20.3.3.5.1.4 of Applicable Document (1), and it constitutes a rebroadcast of the GPS AS flag
and satellite configuration acquired by the QZSS MS. The structure of the message is shown in
Table 5.2.2-2. The combination of SV-ID= 63 and Data-ID="00"(B) won’t be used in future
(5) Almanac Reference Week Number
When the SV-ID= 51 & Data-ID="00"(B), or when SV-ID= 49 ~ 51 & Data-ID="11"(B), bits 17
~ 24 in word 3 indicate the Week Number (WNa) that serves as a reference for the Almanac
Reference Time (toa) (see Section 20.3.3.5.1.2 and 20.3.3.5.2.2 of Applicable Document (1)).
When the Data-ID is "00"(B) & SV-ID= 51, or when Data-ID="11"(B) & SV-ID= 49 or 50, they
indicate GPS Almanac Reference Week Number; when the Data-ID is "11"(B) & SV-ID is 51, it
indicates a QZS Almanac Reference Week Number. The structure of the message is shown in
Table 5.2.2-2.
WNa is made up of 8 bits and is a modulo-256 expression of the GPS Week Number (see Section
6.3.6) used as a reference. Word 3 indicates the toa referenced by WNa.
When the Data-ID = "00"(B) and SV-ID = 51 or Data-ID="11"(B) & SV-ID= 49 or 50, the
Almanac Reference Week Number is the same as in Section 20.3.3.5.1.5 of Applicable
Document (1), and it constitutes a rebroadcast of the GPS Almanac Reference Week Number
acquired by the QZSS MS.
GPS almanac reference week number and almanac reference time broadcasted in the case of
Data-ID="00"(B) & SV-ID= 51 are same as the message in the case of Data-ID="11"(B) and SatID= 49 or 50. Therefore the combination of SV-ID= 51 & Data-ID="00"(B) won’t be used in
future.
(6) Coordinated universal time parameter
When the SV ID is 56, the 24 MSBs of words 6 ~ 9 and the 8 MSBs of word 10 contain the
parameters for correcting UTC time to match GPS time. When the Data-ID is "00"(B), it
indicates a GPS rebroadcast, (the parameters to calculate the time offset between UTC (USNO)
and GPS time). When the Data-ID is "11"(B), it signifies the parameters to calculate the time
offset between UTC (NICT) (with QZSS as the standard) and GPS time.
The structure of the message is shown in Table 5.2.2-2. The number of bits, scale factor, range
and units are the same as in Table 20-IX of Applicable Document (1).
The user algorithm is as noted in Section 6.3.7.
The accuracy of the Coordinated Universal Time (UTC) parameter when the Data-ID is "00"(B)
or "11"(B) is 90 [ns].
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IS-QZSS Ver. 1.6
(7) Ionospheric parameter
When the SV ID is 56, bits 9 ~ 24 in word 3 and the 24 MSBs of words 4 and 5 indicate the
ionospheric parameters for use in the ionospheric model employed by users of only the L1C/A
signal, LIC signal, L2C signal or L5 signal to calculate the ionospheric delay.
When the Data-ID is "00"(B), it indicates a GPS rebroadcast and the parameter is applicable
worldwide.
When the Data-ID is "11"(B), it indicates that the ionospheric parameters have been generated
by QZSS, and that the parameters have been specialized and are applicable within the area
shown in Figure 4.1.5-1. These parameters usually, except ionospheric disturbance, use data for
the past 24 hours (maximum) and are updated at least once each day.
The structure of the message is shown in Table 5.2.2-2. The number of bits, scale factor, range
and units are the same as in Section 20.3.3.2.5 and Table 20-X of Applicable Document (1).
For the user algorithm for users of only one signal, first the internal signal group delay error is
corrected in accordance with Section 6.3.4, and then the ionospheric correction is performed in
accordance with Section 6.3.8.
(8) Navigation Message Correction Table (NMCT)
When the SV-ID= 52–54 & DATA-ID="11"(B), this indicates a Navigation Message Correction
Table (NMCT). When the SV ID is 52, it indicates ERD values for GPS satellites (PRN1 ~
PRN30). When the SV ID is 53, it indicates ERD values for QZS (PRN193 ~ PRN197) and
GPS satellites (PRN31 & 32). When the SV ID is 54, it reserved for spares.
The structure of the message is shown in Table 5.2.2-2. The format of the subframe is defined
as same as the one defined in Applicable Document (1), and the sequence in the subframe is
shown in Table 5.2.2-4. In addition, QZS-1 at current MCS does not transmit effective ERD for
QZS-1 itself. (Invalid data (="100000"(B)) is transmitted.)
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IS-QZSS Ver. 1.6
Table 5.2.2-4 Sequence of NMCT in the frame when Data-ID="11"(B)
ERD Area
SV1
SV2
SV3
SV4
SV5
SV6
SV7
SV8
SV9
SV10
SV11
SV12
SV13
SV14
SV15
SV16
SV17
SV18
SV19
SV20
SV21
SV22
SV23
SV24
SV25
SV26
SV27
SV28
SV29
SV30
Data-ID="11" (B)
SV-ID=52
GPS PRN1
GPS PRN2
GPS PRN3
GPS PRN4
GPS PRN5
GPS PRN6
GPS PRN7
GPS PRN8
GPS PRN9
GPS PRN10
GPS PRN11
GPS PRN12
GPS PRN13
GPS PRN14
GPS PRN15
GPS PRN16
GPS PRN17
GPS PRN18
GPS PRN19
GPS PRN20
GPS PRN21
GPS PRN22
GPS PRN23
GPS PRN24
GPS PRN25
GPS PRN26
GPS PRN27
GPS PRN28
GPS PRN29
GPS PRN30
Data-ID="11" (B)
SV-ID=53
QZS PRN193
QZS PRN194
QZS PRN195
QZS PRN196
QZS PRN197
GPS PRN31
GPS PRN32
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Data-ID="11" (B)
SV0ID=54
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
Spare
The NMCT begins with a 2-bit term indicating availability (AI), followed by a 6-bit ERD value
consisting of up to 30 items.
(a) AI (Availability Indication)
The AI is made up of bits 9 and 10 of Word 3.
00:
01:
10:
11:
Correction table is decoded and can be used
Spare
Correction table cannot be used
Spare
(b) ERD (Estimated Range Deviation)
With regard to the NMCT ERD value, the MSB is the sign bit, while the LSB indicates 0.3
[m], and the data range is ±9.3 [m]. A binary value of "100000"indicates that the ERD value
does not exist. A binary value of "011111" indicates that the ERD value exceeds the upper
limit.
The user algorithm is as noted in Section 6.3.9.1.
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IS-QZSS Ver. 1.6
5.3 L1C Signal
5.3.1 RF Characteristics
5.3.1.1 Signal Configuration
Figure 5.3.1-1 shows the configuration of the L1C signal. The L1C signal is modulated onto the L1
RF carrier (in a similar way, but separately from, the L1 C/A and L1-SAIF QZSS signals) as specified
in Section 5.1. This section specifies how the bit streams are generated for the two L1C signals: the
L1C data signal (L1CD) and the L1C pilot (data-less) signal (L1CP).
The L1CD bit stream is generated by the modulo-2 addition (XOR) of the L1C navigation message
and the L1CD PRN ranging code. The L1CP bit stream is generated by the modulo-2 addition (XOR)
of the L1C overlay code and the L1CP PRN ranging code. Each unique L1C PRN ranging code is at
a chipping rate of 1.023 [Mcps] with a chip length of 10230 [bits] and a duration of 10 [milliseconds].
The L1CP overlay code is at a chipping rate of 100 [bps] with a chip length of 1800 [bits] and a
duration of 18 [seconds].
The L1C navigation message is divided into three subframes (Time of Interval (TOI), Clock &
Ephemeris (C&E) and Variable Data (Var)) that are Bose, Chaudhuri, and Hocquenghem (BCH) and
24-bit Cyclic Redundancy Check (CRC24) encoded. Subframes C&E and Var are further Low Density
Parity Check (LDPC) encoded and subjected to interleaving. Then these subframes are integrated with
the TOI subframe that has been BCH encoded.
TOI
(9bits)
C&E
(576bits)
Var
(250bits)
Outer FEC
Coder
52bits
1800bits/18sec
(BCH 952)
Outer FEC
Coder
600bits
(CRC 24)
Outer FEC
Coder
Inner FEC
½ Coder
1200bits
{s;p1;p2}
(LDPC)
274bits
(CRC 24)
Inner FEC
½ Coder
(LDPC)
Interleaver
1748bits
CNAV2
(100sps)
548bits
{s;p1;p2}
1st PRN
as Ranging Code
L1CD(t)
1.023Mcps
10230chipL
L1CP(t)
2nd PRN
as Overlay Code
L1CO(t)
100cps
1800chipL
Figure 5.3.1-1 L1C Signal Structure
5.3.1.2 Carrier Wave Properties
In accordance with Section 5.1.
64
L1CD
L1CP
IS-QZSS Ver. 1.6
5.3.1.3 Code Properties
5.3.1.3.1 Overview of Code
As noted in Sections 5.3.1.1, there are two types of PRN code used for the L1C signals: unique
PRN ranging codes for L1CD and L1CP, and an overlay code for L1CP. The methods used to
generate both types of code are the same as the methods specified in Applicable Document (3).
Specifically, the method noted in Section 3.2.2.1.1 of Applicable Document (3) is used to generate
the PRN ranging codes. With regard to the specific L1C PRN numbers for the L1CD and L1CP
signals to be broadcast by each QZS from among those numbers listed in Section 6.3.1.1 of
Applicable Document(3), the numbers specified in Section 5.1.1.11.1 of this IS-QZSS document
are to be used.
Similarly, the method noted in Section 3.2.2.1.2 of Applicable Document (3) is used to generate the
overlay codes. With regard to the specific PRN numbers for the overlay code of the L1CP signal to
be broadcast by each QZS from among the numbers listed in Section 6.3.1.2 of Applicable
Document (3), the numbers specified in Section 5.1.1.11.1 of this IS-QZSS document are to be used.
For this reason, an S2 polynomial expression is needed for Fig. 3.2-2 in Section 3.2.2.1.2 of
Applicable Document (3).
5.3.1.3.2 Non-Standard Code
In the event that a problem with the QZSS occurs, a non-standard code (NSC) is transmitted. This
is done to protect the user by ensuring that users do not use erroneous signals.
5.3.2 Messages
5.3.2.1 Message Configuration
As noted in Section 5.3.1.1 in this manual, navigation messages are divided into three subframes: TOI,
C&E, and Var.
This message configuration is the same as specified in Section 3.2.3.1 of Applicable Document (3).
5.3.2.2 Encoding
As noted in Section 5.3.1.1 above, navigation messages are divided into three subframes: TOI, C&E
and Var. Each of these subframes is BCH and CRC24 encoded. Furthermore, C&E and Var are further
subjected to LDPC encoding.
The encoding process used for these subframes is the same as specified in Sections 3.2.3.2 ~ 3.2.3.4
of Applicable Document (3).
5.3.2.3 Interleaving
As noted in the previous section, the C&E and Var subframes that are subjected to LDPC encoding
are also interleaved and then integrated with the TOI subframe that has been BCH encoded.
The interleaving process is the same as in Section 3.2.3.5 of Applicable Document (3).
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IS-QZSS Ver. 1.6
5.3.2.4 Message Content
With the exception of the list in Section 8.1.3, the content of the L1C message for QZSS is the same
as that for GPS as specified in Section 3.5 of Applicable Document (3).
5.3.2.4.1 TOI (Subframe 1)
Prior to encoding, the TOI subframe is made up of 9 bits. TOI is incremented by 1 at each message
period (= 18 [seconds]). TOI reverts to 0 every two hours.
The valid range is 0-399. The initial TOI value for a two-hour period is 1. The final TOI value for
a two-hour period is 0.
These values are the same as the values specified in Sections 3.5.1 and 3.5.2 of Applicable
Document (3).
5.3.2.4.2 C&E (Subframe 2)
Prior to encoding, C&E (subframe 2) is composed of 576 bits. The C&E data is used to calculate
the orbital position and time of the QZS.
This subframe includes the Ephemeris data, etc. for the satellite, such as the data shown in Table
5.3.2-1. For an overview, see Section 3.5.3 of Applicable Document (3).
In all other respect except as specified in Section 3.1.2.1.2 and (10) "Integrity Assurance" in this
section, this subframe is the same as specified in Section 3.5.3 of Applicable Document (3).
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IS-QZSS Ver. 1.6
Table 5.3.2-1 Definition of Ephemeris parameters and SV clock parameters for Navigational
Message DL1C
Parameter
Definition
WNn
GPS Week Number
ITOW
Interval time of week (ITOW) count defined as
being equal to the number of two-hour epoch
that has occurred since the transition from the
previous week.
top
Data predict time of week (seconds into week)
L1C Health
L1C signal health
URAED index
ED Accuracy Index
toe
Ephemeris epoch (seconds into week)
∆A
Difference from Semi-Major Axis at toe
In the case of QZS, indicates difference with
42,164,200 [m]
A
Difference from GPS definition
Change rate in Semi-Major Axis
∆n0
Difference from mean motion calculation at toe
∆n 0
Change rate in mean motion of calculation
M0-n
Mean anomaly at toe
en
Eccentricity
ωn
Argument of perigee
Ω0-n

∆Ω
Longitude of ascending node at the beginning
of the week
Rate of right ascension of ascending node
(RAAN) difference from reference value*1
i0-n
Orbit inclination at toe
io-n-DOT
Change rate in Orbit inclination
QZSS does not limit the numerical range
(In GSS, Maximum value =
0.03).
Cuc-n
Amplitude of the sine harmonic correction term
to the angle of inclination
Amplitude of the cosine harmonic correction
term to the angle of inclination
Amplitude of the sine harmonic correction term
to the orbit radius
Amplitude of the cosine harmonic correction
term to the orbit radius
Amplitude of the sine harmonic correction term
to the argument of latitude
Amplitude of the cosine harmonic correction
term to the argument of latitude
URANED0 index
NED Accuracy index
URANED1 index
NED Accuracy change index
URANED2 index
NED Accuracy change rate index
af2-n
SV clock drift rate correction term
af1-n
SV clock drift correction term
af0-n
SV clock bias correction term
Cis-n
Cic-n
Crs-n
Crc-n
Cus-n
TGD
ISCL1CP
ISCL1CD
In the case of GPS, indicates difference
with 26,559,710 [m]
LCQZSS*2 and L1C/A group delay difference
correction term
Inter-Signal Correction Term for L1CP
(between L1C/A and L1CP)
Inter-Signal Correction Term for L1CD
(between L1C/A and L1CD)
67
LCGPS*3 and L1P(Y) for GPS
L1P(Y) – L1CP for GPS
L1P(Y) – L1CD for GPS
IS-QZSS Ver. 1.6
WNOP
Data Predict Week Number, identifying the
GPS week to which the top term refers

*1 Relative to Ω
[semi-circles/second] (same value with GPS)
REF = −2.6 × 10
*2 LCQZSS: LCQZSS is the ionospheric error free linear combination of the L1C/A and L2C signals for QZSS
*3 LCGPS: LCGPS is the ionospheric error free linear combination of the L1P(Y) and L2P(Y) signals for GPS
−9
(1) Transmission Week No.
Bits 1–13 of subframe 2 constitute a binary expression for the modulo-8192 representation of
the current GPS Week Number.
This is the same as in Section 3.5.3.1 of Applicable Document (3).
(2) ITOW (Interval Time Of Week)
Bits 14–21 of subframe 2 constitute a number that is incremented by 1 every two hours starting
from the beginning of the GPS week.
The valid range is 0–83. The ITOW value for the two-hour period just prior to the week
changeover is 83. The ITOW value for the first two-hour period of the week is 0.
This is the same as in Section 3.5.3.2 of Applicable Document (3).
The calculated "time of week" using TOI defined in Section 5.3.2.4.1 and ITOW is not always
same as actual GPS time. This inconsistency occurs every two hours.
End/Start of week (GPS time)
2-hour epoch
Corresponding time
to the message
Actual GPS Time
18 seconds
2-hour epoch
TOI=399
TOI=0
ITOW=83 ITOW=83
WN=1
WN=1
TOI=1
ITOW=0
WN=2
TOI=0
ITOW=0
WN=2
TOI=1
ITOW=1
WN=2
1week,
1week,
2week,
2week,
2week,
604782s
597600s
18s
0s
7218s
1week,
1week,
2week,
2week,
2week,
2week,
604764s
604782s
0s
7182s
7200s
7218s
same
NOT same !
time
NOT same !
The corresponding time to the
message dose not increase
continuously .
Figure 5.3.2-1 Relationship between TOI, ITOW & time of week
(3) top (time at which Ephemeris data estimate is made)
Bits 22-32 of subframe 2 represents the time at which the Ephemeris data estimate is made (top).
This is the same as in Section 3.5.3.3 of Applicable Document (3).
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IS-QZSS Ver. 1.6
(4) Signal Health (L1)
The single bit 33 of subframe 2 indicates the health of the L1C signal transmitted by the satellite.
Signal health is expressed as follows.
0
1
No problems with signal
Problem with signal exists or signal cannot be used
As an operation specific to the QZSS, this bit expresses the result of a comparison with the
present status of the satellite as determined through monitoring. For more information, see
Section 5.1.2.1.3.
Additional SV health data are present on pages 3 and 4 of subframe 3 as well. The data in
message type 10 are uploaded at a different time, so these data may differ from the data for the
satellites transmitting other messages and other satellite data.
In all other respects, this is the same as in Section 3.5.3.4 of Applicable Document (3).
(5) Elevation Dependent Accuracy Indicator: URAED Index
Bits 34-38 of subframe 2 indicate the Elevation-Dependent (ED) component User Range
Accuracy indicator. For more information, see Section 5.1.2.1.3.2.
In all other respects, this is the same as in Section 3.5.3.5 of Applicable Document (3).
(6) Ephemeris Data
The Ephemeris data for the corresponding satellite shown in Table 5.3.2-1 are transmitted in
Subframe 2. The algorithm used to determine the orbital position of the satellite is in accordance
with Section 6.3.5.
With the exception of the QZSS-unique semi major axis parameter (specified in (a) below), the
ephemeris data characteristics (number of bits, LSB scale factor, data range and units) are the
same as in Table 3.5-1 of Applicable Document (3).
The data structure (data sequence etc.) is the same as in Fig. 3.5-1 of Applicable Document (3).
(a) Semi Major Axis Difference ∆A
∆A is the difference between the QZS semi major axis at toe A (toe) and 42,164,200 [m]:
∆A (toe) = A (toe) – 42,164,200 [m]
(7) Clock Parameters
The SV clock parameters for the satellite, shown in Table 5.3.2-1, are transmitted. The user
algorithm is the same as in Section 20.3.3.3.3.1 of Applicable Document (1). However, some
of the parameter definitions are different. For more information, see Section 6.3.2.
The epoch toe in the ephemeris data contained in bit 39–49 of subframe 2 is used as the epoch
for the clock parameters. This is the same as in Section 3.5.3.7 of Applicable Document (3).
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IS-QZSS Ver. 1.6
(8) Non-Elevation Dependent Accuracy Indicator: URANED Index
Bits 460–470 of subframe 2 contain the parameters needed to determine URANED, which
indicates the Non-Elevation-Dependent (NED) User Range Accuracy. For more information,
see Section 5.1.2.1.3.2.
With regard to the epoch for the accuracy indicator of the SV clock parameters, bits 22–32 of
subframe 2 use the time top estimated by the Ephemeris data. This is the same as in Section
3.5.3.8 of Applicable Document (3).
The algorithm used to determine the specific user range accuracy (URANED) expressed by
URANED index is the same as in Section 3.5.3.8 of Applicable Document (3).
For more information about the method of use and the content of URANED, see Sections
3.1.2.1.3 and 5.1.2.1.3, respectively.
(9) Calculation of Group Delay Error
Bits 527–565 of subframe 2 constitute the parameters TGD, ISCL1CP and ISCL1CD used to
calculate the group delay error for users of only the L1C signal (i.e., single-frequency users).
The numbers of bits, scale factors, ranges and units are the same as in Table 3.5-1 of Applicable
Document (3). However, if bit string for each parameter is "1000000000000", it indicates that
the group delay differential correction parameters cannot be used.
Related algorithms are shown in Sections 6.3.3 and 6.3.4.
(10) Integrity Assurance
One bit of bits 566 of subframe 2 of GPS is "Integrity Status Flag" (Refer to Applicable
Document (3) Section 3.5.3.10). But QZS-1 at current MCS does not adopt this Flag (fixed at
"0"(B)).
(11) Data Predict Week Number
Bits 567–575 of subframe 2 indicate the Data Predict Week Number (WNOP) to which the Data
Predict Time of Week (top) is referenced (see section 5.3.2.4.2(3)). The WNOP term consists of
eight bits which shall be a modulo 256 binary representation of the GPS week number to which
the top is referenced.
5.3.2.4.3 Var (Subframe 3)
Var (subframe 3) comprises 250 [bits] prior to encoding. This subframe is used to transmit other
data using multiple pages.
Subframe 3 begins with 8 [bits] (193–197) that indicate the QZS satellite number from which the
signal is transmitted, followed by a 6-bit page number.
This is the same as in Section 3.5.4 of Applicable Document (3).
5.3.2.4.3.1 PRN No.
Bits 1–8 of subframe 3 constitute an 8-bit PRN number representing the PRN number for the QZS
transmitting that message.
This is the same as in Section 3.5.4 of Applicable Document (3).
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5.3.2.4.3.2 Page No.
Bits 9–14 of subframe 3 constitute a 6-bit page number signifying the information contained in
that frame.
The relationship between the individual page numbers and the corresponding information is
shown in Table 5.3.2-2. Details are shown in Section 5.3.2.4.3.3. Table 5.3.2-2 also shows the
maximum intervals at which each individual parameter is transmitted.
Multiple QZS satellites may use completely different timings to transmit the data identified by
page numbers. As a result, when the signals from multiple QZS satellites are received, all data
sets can be collected at intervals that are shorter than the data set transmission interval for a single
QZS satellite.
As noted in Section 3.5.5 of Applicable Document (3), each page is transmitted using an arbitrary
timing, so users should not expect a set pattern.
Table 5.3.2-2 Definition of page number and Maximum transmit Intervals for Navigational
Message DL1C
Maximum transmit Notes
Page Message data
Interval
1
Ionospheric parameter, UTC parameter
288 seconds
2
GGTO (GPS–QZSS Time Offset), EOP
288 seconds
3
Reduced Almanac of QZSS
4
5
Midi Almanac of QZSS
120 minutes
Differential correction (DC) data
30 minutes (*)
[Ephemeris correction data, SV clock correction data］
6
Text
As needed
7
–
19
Spare
Ionospheric parameter, UTC parameter (GPS
Rebroadcasting)
GGTO (GPS–GNSS(Galileo and GLONASS) Time
Offset) (GPS Rebroadcasting)
Reduced Almanac of GPS (GPS Rebroadcasting)
20
Midi Almanac of GPS (GPS Rebroadcasting)
*
17
18
20 minutes
*
*
*
* We will not define the maximum transmit period for GPS rebroadcasting parameters and GPS DC data.
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5.3.2.4.3.3 Content of Individual Pages
(1) Page No. 1 (17):
UTC parameters/Ionospheric parameters
Page 1 (17) includes the UTC parameters and ionospheric parameters such as shown in Table
5.3.2-3. For an overview, see Section 3.5.4.1 of Applicable Document (3).
Table 5.3.2-3 Definition of UTC parameters and Ionospheric parameters for Navigational
Message DL1C
Parameter
Definition
Difference from GPS definition
A2-n
Bias coefficient of GPST time scale relative
to UTC time scale
Drift coefficient of GPST time scale relative
to UTC time scale
Drift rate coefficient of GPST time scale
relative to UTC time scale
∆tLS
Current or past leap second count
A0-n
A1-n
tot
UTC parameters
WNot
WNLSF
DN
∆tLSF
Current or future leap second count
α0
Ionospheric parameter α0 for Klobuchar
model
Ionospheric parameter α1 for Klobuchar
model
Ionospheric parameter α2 for Klobuchar
model
Ionospheric parameter α3 for Klobuchar
model
Ionospheric parameter β0 for Klobuchar
model
Ionospheric parameter β1 for Klobuchar
model
Ionospheric parameter β2 for Klobuchar
model
Ionospheric parameter β3 for Klobuchar
model
Inter Signal Correction Term for L1C/A
(between L1C/A and L1C/A) (Transmitting
value is 0.0)
α1
α2
Group Delay Differential Ionospheric parameters
Correction Parameters
Seconds into week for UTC and GPST bias
calculation
GPS Week Number for UTC and GPST bias
calculation
GPS Week Number at the end of which the
leap second becomes effective.
Day number at the end of which the leap
second becomes effective (First day
number = 1).
α3
β0
β1
β2
β3
ISCL1C/A
When page No. is 1:
Parameters indicate UTC(NICT)
When page No. is 17 (rebroadcast of
GPS message):
Parameters indicates UTC(USNO)
When page No. is 1: Parameters are
optimized for Japan & environs
When page No. is 17 (rebroadcast of
GPS message): Parameters can be
applied on global area
L1P(Y) – L1C/A for GPS
ISCL2C
Inter Signal Correction Term for L2C
(between L1C/A and L2C)
L1P(Y) – L2C for GPS
ISCL5I5
Inter Signal Correction Term for L5I5
(between L1C/A and L5I5)
L1P(Y) – L5I5 for GPS
ISCL5Q5
Inter Signal Correction Term for L5Q5
(between L1C/A and L5Q5)
L1P(Y) – L5Q5 for GPS
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(a) UTC Parameters
The UTC parameters are the parameters needed to relate GPS time to UTC (NICT).
The numbers of bits, scale factor, range, units, LSB, user algorithm, etc. are all the same as
Section 3.5.4.1 in Applicable Document (3).
(b) Ionospheric Parameters
The ionospheric parameters are the parameters used when users of only one signal (L1, L2
or L5) employ an ionospheric model to calculate the ionospheric delay.
The user algorithm for single signals is in accordance with Sections 6.3.4 and 6.3.8.
The ionospheric parameters, optimized for the area near Japan, are specialized and apply to
the area shown in Figure 4.1.5-1. These parameters use the data for the past 24-hour period
(maximum) and are updated at least once daily, except ionospheric maximum period.
The number of bits, scale factor, range and units are the same as Section 3.5.4.1.2 in
Applicable Document (3).
(c) Group Delay Differential Correction Parameters
Group delay is defined as the delay between the timing of the signals radiated output of GPS
satellite/QZS-1 (measured at the antenna phase center) and L1-C/A signal from that satellite.
The delay consists of a bias term and an uncertainty.
The bit location and length of these parameters are the same as in Figure 3.5-2 of Applicable
Document (3). However, if bit string for each parameter is "1000000000000"(B), it indicates
that the group delay differential correction parameter cannot be used.
Related algorithms are shown in Sections 6.3.3 and 6.3.4.
(2) Page No. 2 (18):
GPS/GNSS Time Offset (GGTO) Parameters, Earth
Orientation Parameters (EOP)
Page 2(18) includes the GPS/GNSS (QZSS, Galileo and GLONASS) Time Offset (GGTO)
Parameters, parameters that are used to adjust GPS time to match other GNSS system times, as
shown in Table 5.3.2-4, the Earth Orientation Parameters (EOP) that indicate the relationship
between the earth's rotational axis and the Japan satellite navigation Geodetic System (JGS).
With regard to the content of these parameters, see Section 3.5.4.2 in Applicable Document (3).
The bit definition, number of bits, scale factor (LSB), range and units are all the same as Table
3.5-4 and 3.5-5 in Applicable Document (3).
Page 18 is rebroadcast of GPS message.
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Table 5.3.2-4 Definition of GPS GNSS Time Offset and Earth Orientation Parameters for
Navigational Message DL1C
Earth orientation parameters EOP
GNSS time offset GGTO
Parameter
Definition
Difference from GPS definition
A2GGTO
Bias coefficient of GPST time scale relative to
other GNSS time scale
Drift coefficient of GPST time scale relative to
other GNSS time scale
Drift rate coefficient of GPST time scale
relative to other GNSS time scale
tGGTO
Seconds into GGTO reference week
WNGGTO
GGTO Reference Week Number
GNSS ID
See (a) in this section
tEOF
Seconds into EOP reference week
PMX
X-Axis polar motion value at tEOF
d
PM X
dt
X-Axis polar motion drift at tEOF
PMY
Y-axis polar motion value at tEOF
d
PM Y
dt
Y-axis polar motion drift at tEOF
∆UT1
UT1-UTC difference at tEOF
A0GGTO
A1GGTO
d
∆UT1
dt
In GPS, GNSS ID="011"(B) means
Spare
Rate of UT1-UTC difference at tEOF
(a) GNSS-ID
Bits 15–17 define the other GNSS that apply the GPS GNSS Time Offset (GGTO) parameters.
The three-bit definitions are as follows:
000
001
010
011
100–111
Data cannot be used
Galileo
GLONASS
QZSS
Spare
(b) GPS/GNSS Time Offset (GGTO)
The algorithms used to derive GPS – GNSS (QZSS, Galileo and GLONASS) Time Offset
(GGTO) are the same as in Applicable Document (3).
However, the SV clock parameter for the QZS already uses GPST as the standard, so the time
offset between the GPS and QZSS (GQTO) is always zero.
In the case of Page 18, it is rebroadcast of GPS message and the validity period of the GGTO
should be 1 day as a minimum (refer to section 3.5.4.2.1 in Applicable document (3)).
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(c) Earth Orientation Parameter (EOP)
The definition, number of bits, scale factor, range, units, LSB, user algorithm etc, are all the
same as Section 3.5.4.2.2 in Applicable Document (3).
When page number is 18, i.e. the page for rebroadcasting GGTO in GPS CNAV2 (Civil
Navigation 2) message (=Navigation message of L1C signal), since QZSS does not broadcast
EOP obtained from GPS CNAV message, the information obtained from bits 83 to 220 cannot
be used (In the transmitted data, all bits are fixed at "0").
(3) Page No. 3 (19):
Reduced Almanac
Page 3 includes the Reduced Almanac, as shown in Table 5.3.2-5. For an overview, see Section
3.5.4.3.5 in Applicable Document (3).
The bit definition, number of bits, scale factor (LSB), range and units are all the same as Figure
3.5-9 and Table 3.5-6 in Applicable Document (3).
When the PRN number is 63 (PRN No. = "111111"(B)) in QZS-1 at current MCS, the data packet
includes dummy data without any effective information. The 22 bits are alternating ones and
zeros, and the last 3 bits, which indicates the health, are all "1"s ("111"(B)). When the PRN
number is 0 (PRN No. = "000000"(B)), the data packet includes dummy data in GPS but not
acquired in QZS-1 at current MCS. The 22 bits are all "0"(B)s for QZS-1.
The user algorithm is in accordance with Section 6.3.6.
The Reduced Almanac is transmitted from a single satellite in a shorter period of time than the
Midi Almanac.
The Reduced Almanac data for the QZS are updated at least once every 3 days. The velocity
calculated by the Reduced Almanac data is accurate within 350 [m/s].
Page 19 is rebroadcast of GPS message.
Table 5.3.2-5 Definition of Reduced Almanac parameters for Navigational Message DL1C
Parameter
Definition
WNa-n
GPS Week Number at the time of Reduced
Almanac generation
toa
Reduced Almanac epoch (seconds into week)
Ω0
PRN number (range 0 ~ 255) for satellite for
which Reduced Almanac will be applied.
1–32 if target is GPS; 193–197 if target is QZSS
Offset from the nominal QZS Semi-Major Axis
of 42,164,200 [m]
Longitude of ascending node at the beginning of
the week
Φ0
Argument of latitude ( = M0 + ω)
(e)
Implicit eccentricity (0.075 in the case of QZS)
(Precondition for above parameter)
0 in the case of GPS
(δi)
Fixed at –0.0111 [semi-circles], the offset from
reference QZS orbit inclination of 0.25 [semicircles]
(precondition for above parameter)
In the case of GPS, fixed at 0.0056 [semicircles], the offset from 0.3 [semicircles]
L1/L2/L5
Health
L1,L2 and L5 signal health
(ω)
Implicit Argument of Perigee (270 [deg] in QZS1) (Precondition for above parameters)
PRN No.
δA
Reduced Almanac×6 satellites
Difference from GPS definition
75
For GPS, PRN number is extended to 1 ~
63, but it is not supported by QZS-1 at
current MCS.
In the case of GPS, indicates the offset
from 26,559,710 [m]
0[deg] in case of GPS
IS-QZSS Ver. 1.6
(a) Reduced Almanac Epoch (Week Number)
Bits 15-27 of subframe 3 indicate the Week Number (WNa-n) corresponding to the Reduced
Almanac epoch (toa).
WNa-n is made up of 13 bits and is expressed by the modulo-8192 value for the GPS Week
Number (see Section 6.3.6) that serves as a reference for toa.
This is the same as Section 3.5.4.3.1 in Applicable Document (3).
(b) Reduced Almanac Epoch (seconds into week)
Bits 28–35 of a subframe 3 indicate the Reduced Almanac epoch (toa).
This is the same as Section 3.5.4.3.1 in Applicable Document (3).
(c) 6 Reduced Almanac Packets
Bits 36–233 of subframe 3 include six Reduced Almanac packets comprising 33 bits each.
This is the same as Section 3.5.4.3.5 in Applicable Document (3).
(d) PRN Number
Bits 1–8 in each packet constitute the PRN number for the satellite indicated by that packet.
The PRN number constitutes 8 bits and expresses a value from 0 to 255. The definition of
these values is as follows.
1–32:
65–94:
129–160:
193–197:
GPS PRN No.*
The value minus 64 indicates a Galileo PRN No.
The value minus 128 indicates GLONASS PRN No.
QZSS PRN No.
* According to Applicable document (3), PRN No. for GPS satellites are extended to 1 ~ 63,
but it would not be supported by QZS-1 at current MCS.
(e) Semi major axis
Bits 9–16 in each packet provide the data (δA) relating to the semi major axis of the satellite
indicated by the PRN number.
• For QZSS:
• For GPS:
A = 42,164,200[m] + δ A
A = 26,559,710[m] + δ A
(f) Longitude of Ascending Node at the beginning of the week
Bits 17–23 in each packet are the longitude of ascending node (Ω0) at the beginning of the
week for the satellite indicated by the PRN number.
This is the same as Figure 3.5-9 in Applicable Document (3).
(g) Argument of Latitude
Bits 24–30 in each packet constitute the argument of latitude for the satellite indicated by the
PRN number.
This is the same as Figure 3.5-9 in Applicable Document (3).
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(h) Implicit Eccentricity
For the eccentricity, although this is not broadcasted as Reduced Almanac from QZS, users
may use the following assumption.
• For QZSS:
• For GPS:
e = 0.075
e = 0.0
(i) Implicit Inclination
For the inclination, although this is not broadcasted as Reduced Almanac from QZS, users
may use the following assumption.
• For Q2SS:
• For GPS:
i = 43 [deg]
i = 55 [deg]
(j) Implicit Time Change Rate for Right Ascension of Ascending Node (RAAN)
For the time change rate for the right ascension of ascending node (RAAN), although this is
not broadcasted as Reduced Almanac from QZS, users may use the following assumption.
• For QZSS:
• For GPS:
 = −8.7 ×10 −10 [semi − circles/second]
Ω
 = −2.6 ×10 −10 [semi − circles/second]
Ω
(k) Signal Health (L1/L2/L5)
The three one-bit health indicators (bits 31, 32 and 33) in each packet relate to the
corresponding L1, L2 and L5 signals of the satellite with the associated PRN number.
Their significance is in accordance with Section 5.1.2.1.3.
(l) Implicit Argument of Perigee
For the argument of perigee, although this is not broadcasted as Reduced Almanac from QZS,
users may use the following assumption.
• For QZSS:
• For GPS:
ω = 270[deg]
ω = 0[deg]
(4) Page No. 4 (20): Midi Almanac
Page 4 includes a Midi almanac like the one shown in Table 5.3.2-6. For an overview, see
Section 3.5.4.3.6 in Applicable Document (3).
The bit definition, number of bits, scale factor (LSB), range and units are all the same as in
Figure 3.5-5 and Table 3.5-7 in Applicable Document (3).
The user algorithm is in accordance with Section 6.3.6.
The Midi Almanac data for the QZS are updated at least once every 6 days. The velocity
calculated by the Midi Almanac data is accurate with 30 [m/s].
Page 20 is rebroadcast of GPS message.
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Table 5.3.2-6 Definition of Midi Almanac parameters for Navigational Message DL1C
Parameter
Definition
Difference from GPS definition
L1/L2/L5 Health
GPS Week Number at time of Midi
Almanac generation
Midi Almanac epoch (seconds into week)
PRN number (range 0 ~ 255) for satellite
for which Midi Almanac will be applied.
1-32 if GPS; 193-197 if QZSS
L1,L2 and L5 signal health
Δe
Eccentricity
(offset from reference eccentricity 0.06)
WNa-n
toa
PRN No.
Ω
Offset from reference inclination 0.25
[semi-circles]
(Offset from 0.25 [semi-circles]= 45 [deg])
Change rate in Right ascension of
ascending node (RAAN)
Square root of Semi-Major Axis
Longitude of ascending node at the
beginning of the week
Argument of perigee
M0
Mean anomaly
af0
SV Clock bias correction coefficient
af1
SV Clock drift correction coefficient
Δi

Ω
A
Ω0
For GPS, PRN number is extended to 1
~ 63, but it is not supported by QZS-1 at
current MCS.
In the case of GPS, the eccentricity value
itself (offset from reference eccentricity
0)
In the case of GPS, the reference
inclination is 0.3 [semi-circles], which
represents 54 [deg].
(a) Midi Almanac Epoch (Week Number)
Bits 15–27 indicate the Week Number (WNa-n) corresponding to the Midi Almanac epoch
(toa).
WNa-n is made up of 13 bits and is expressed by the modulo-8192 for the GPS Week Number
(see Section 6.3.6) that serves as a reference for toa.
This is the same as Section 3.5.4.3.1 in Applicable Document (3).
(b) Midi Almanac Epoch (seconds into week)
Bits 28-35 indicate the Midi Almanac epoch (toa).
This is the same as Section 3.5.4.3.1 in Applicable Document (3).
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(c) PRN Number
Bits 1–8 in each packet constitute the PRN number for the satellite.
The PRN number constitutes 8 bits and expresses a value from 0 to 255. Within this range,
the number categories are as follows.
1 ~ 32:
65 ~ 94:
129 ~ 160:
193 ~ 197:
GPS PRN No.*
The value minus 64 indicates a Galileo PRN No.
The value minus 128 indicates GLONASS PRN No.
QZSS PRN No.
* According to Applicable document (3), PRN No. for GPS satellites are extended to 1 ~ 64,
but it would not be supported by QZS-1 at current MCS.
(d) Signal Health (L1/L2/L5)
The three one-bit health indicators (bits 44, 45, 46) relate to the L1, L2 and L5 signals of the
satellite corresponding to the PRN number.
Their significance is in accordance with Section 5.1.2.1.3.
(e) Content of Midi Almanac Data
Bits 47–165 include the Midi Almanac data for one satellite.
With the exception of the eccentricity and inclination described below, this is the same as
Figure 3.5-5 in Applicable Document (3).
(f) Eccentricity
Bitts 47–57 provide data δ e relating to eccentricity e for the satellite indicated by the PRN
number. However, the QZS eccentricity differs from that of GPS and is provided relative to
the reference values as noted below.
• For QZSS:
ea = 0.06 + δ e
• For GPS:
ea = δ e
ea :
δe:
Actual eccentricity value
Eccentricity value included in navigation message
(g) Inclination
Bitts 58–68 provide data
number.
• For QZSS:
• For GPS:
ia:
δi:
δ i relating to inclination for the satellite indicated by the PRN
ia = 0.25 + δ i [semi-circle]
ia = 0.3 + δ i [semi-circle]
Actual inclination value
Inclination value included in navigation message
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(5) Page No. 5: Differential Correction Data (DC data)
Page 5 includes differential correction data (DC data) for one satellite, as shown in Table 5.3.27. This parameter provides the user with correction terms for the SV clock parameters and
Ephemeris data transmitted by other satellites. DC data are packetized data comprising a 34-bit
SV clock error (CDC) correction parameter and a 92-bit Ephemeris error (EDC) correction
parameter. The CDC and EDC data form a pair; users must use CDC and EDC with the same
top-D and tOD as a pair.
For a DC Data Type indicator, "0" indicates that the correction applies to L1C Navigation
Message (CNAV2) data. "1" indicates that the correction applies to the navigation message for
the L1C/A signal.
The content of the data packet is the same as Section 3.5.4.4 in Applicable Document (3) and
is shown in Table 5.3.2-7.
The bit definition, number of bits, scale factor, range and units for DC data are the same as
Section 3.5.4.4 in Applicable Document (3).
If the DC data is not effective, the value of the PRN Number is set to "11111111"(B) as Section
3.5.4.4.4.1 in Applicable Document (3). In this case, DC data type indicator is set to "0".
Table 5.3.2-7 Definition of DC data for Navigational Message DL1C
Parameter
Definition
top-D
tOD
DC
Data
indicator
Type
PRN No.
δaf0
CDC
δaf1
Prediction time of week for DC data
(seconds in week)
Reference time of week for DC data
(seconds in week)
1:For DL1C/A message
0:For DL1C message
PRN No. (range 0 - 255) for satellite for
which DC data will be applied.
1 ~ 32 if target is GPS; 193-197 if target is
QZSS
Bias correction term for SV clock
∆α
Drift correction term SV clock
User Differential Range Accuracy
(UDRA) index
PRN No. (range 0 - 255) for satellite for
which DC data will be applied.
1 ~ 32 if target is GPS; 193-197 if target is
QZSS
α correction term for Ephemeris parameter
∆β
β correction term for Ephemeris parameter
∆γ
γ correction term for Ephemeris parameter
∆i
Correction term for orbit inclination
Correction term for right ascension of
ascending node (RAAN)
Correction term for Semi-Major Axis
UDRA index
PRN No.
∆Ω
EDC
Difference from GPS definition
∆A
．
UDRA index
UDRA rate index
80
For GPS, PRN number is extended
to 1 ~ 63, but it is not supported by
QZS-1 at current MCS.
For GPS, PRN number is extended
to 1 ~ 63, but it is not supported by
QZS-1 at current MCS.
IS-QZSS Ver. 1.6
DC data include the following. The use of these data is in accordance with Section 3.1.2.1.3.4.
(a) Time of DC data Estimation (top-D)
"top-D" indicates the time (seconds into week) at which DC data are estimated. This is the
same as Section 3.5.4.4.2 in Applicable Document (3).
(b) DC Data Epoch (tOD)
"tOD" indicates the epoch (seconds into week) of DC data. This is the same as Section
3.5.4.4.3 in Applicable Document (3).
(c) Identification of Satellite PRN
The 8-bit PRN specifies the satellite to which DC data applies. A PRN of 1–32 indicates GPS.
A PRN of 193–197 indicates QZSS. (According to Applicable document (3), PRN No. for
GPS satellites are extended to 1 ~ 63, but it would not be supported by QZS-1 at current
MCS.)
When all of the bit values are "1"(PRN No. = "11111111"(B)), it indicates that there are no DC
data in the data block. In such cases, as Section 3.5.4.4.1 in Applicable Document (3),
alternate bit values of "1" and "0" are entered for the remaining data.
(d) Use of CDC Data
This is the same as Section 3.5.4.4.4 in Applicable Document (3). For more information, see
Section 6.3.9.2.
(e) Use of EDC Data
This is the same as Section 3.5.4.4.4 in Applicable Document (3). For more information, see
Section 6.3.9.2.
(f) Accuracy of DC Data
UDRAop-D and UDRA-DOT indicate the ranging accuracy after the DC data have been
applied to the SV clock parameters and Ephemeris data.
The bit definition, number of bits, etc., and user algorithms are the same as Section 3.5.4.4.4
and Table 3.5-10 in Applicable Document (3).
The use of this value is in accordance with Section 3.1.2.1.3.5.
(6) Page No. 6: Text Message
Page 6 includes 29 eight-bit ASCII characters.
All bit definitions, number of bits, etc., are in accordance with Figure 3.5-7 in Applicable
Document (3).
(7) Page No. 7: (Reserved)
(Reserved): Same as Section 3.5.4.6 in Applicable Document (3).
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5.4 L1-SAIF signal
5.4.1 RF characteristics
5.4.1.1 Signal configuration
In accordance with Section 5.1.
5.4.1.2 Carrier wave properties
In accordance with Section 5.1.
5.4.1.3 Code properties
5.4.1.3.1 Code attributes
Same as in Sections 3.2.1.3 and 3.3.2.3 of Applicable Document (1). However, the PRN code is as
described in Section 5.1.1.11.2 of this document.
5.4.2 Error Correction Code
The data transmission rate for the L1-SAIF message is 250 [bps]. However, the data bits are encoded
by the Forward Error Correction (FEC) generator resulting in a 500 [sps] message for transmission. The
FEC encoding factor is ½ and the constraint length is 7. Figure 5.4.2-1 shows the FEC generator used
for encoding. G1 register tap is selected for the first 2 [msec] of a 4 [msec] message stream for 250 [bits]
and G2 tap is done for latter 2 [msec] message.
G2 (133 OCTAL)
+
+
G1 is selected initially
+
+
OUTPUT SYMBOLS
DATA INPUT(250 BPS)
(500 SPS)
ALTERNATING G1/G2
+
+
+
+
G1 (171 OCTAL)
SYMBOL CLOCK
Figure 5.4.2-1 FEC Generation Method
5.4.3 Message
The content of the SAIF (Submeter-class Augmentation with Integrity Function) message broadcast
using the L1-SAIF signal is specified below.
5.4.3.1 Message Configuration
Each message in the L1-SAIF signal is made up of 250 [bits] and has the format shown in Figure
5.4.3-1. The data rate is 250 [bps], so one message is transmitted every second.
The 8-bit preamble begins from bit 1 of the 250-bit message. Next, the 6-bit message type identifier
is inserted (bits 9-14). The 212-bit data domain begins from bit 15, and the 24-bit CRC parity begins
from bit 227. The message transmission sequence is not specified; any message type may be
transmitted during any one-second period.
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IS-QZSS Ver. 1.6
DIRECTION OF DATA FLOW FROM SATELLITE;
MOST SIGNIFCANT BIT(MSB) TRANSMITTED FIRST
250 BITS – 1 SECOND
212-BIT DATA FIELD
24-BITS
PARITY
6-BIT MESSAGE TYPE IDENTIFIER (0-63)
8-BIT PREAMBLE OF 24 BITS TOTAL IN 3 CONTIGUOUS BLOCKS
Figure 5.4.3-1 Message Block Format
5.4.3.1.1 Preamble
The preamble added to the beginning of each message consists of the following three patterns
repeated in sequence:
Pattern A
Pattern B
Pattern C
01010011
10011010
11000110
The start of transmission of the first bit in the "Pattern A" preamble is synchronous with the epoch
of the 6-second L1C/A signal navigation message subframe. The preamble of the next message to
be transmitted after the message with the "Pattern A" preamble is "Pattern B". After "Pattern B"
comes "Pattern C". After that, the sequence returns to "Pattern A".
FEC encoding is performed for preambles in the same manner as for the other bits in the message
block. Accordingly, while the preamble indicates the beginning of the message block, it cannot be
used for signal acquisition prior to FEC decoding or for bit synchronization.
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IS-QZSS Ver. 1.6
5.4.3.1.2 Message Type
Each message has a 6-bit Message Type ID. Messages are identified by a Message Type ID ranging
from 0 to 63. The content of the data field is defined as noted below according to the Message Type.
Table 5.4.3-1 shows a list of message types.
Message Type ID
Table 5.4.3-1 SAIF Message Types
Message Name
Remarks
0
Test mode
1
PRN mask
2~5
Fast Correction & UDRE
6
Integrity data
7
(Fast Correction Degradation Factor)
10
Degradation Parameter
12
Timing Information
18
IGP mask
24
Fast/Long-term Correction
25
Long-term Correction
26
Ionospheric Delay & GIVE
28
Clock-ephemeris Covariance
40 ~ 51
Reservation for applications demonstration
52
TGP mask
53
Tropospheric Delay Correction
54 ~ 55
(Atmospheric delay correction)
56
Inter Signal Bias Correction data
57
(Reserved for orbital information)
58
QZS ephemeris
59
62
QZSS Almanac data
(Regional
information/maintenance
schedule)
(Reserved for Inertial test)
63
Null message
60
(IGP: Ionospheric Grid Point)
L1-SAIF+ Unique Message
(TGP: Tropospheric Grid
Point)
TBD
TBD
TBD
TBD
5.4.3.1.3 CRC Parity
A 24-bit CRC parity code is added to the end of the message. In the event of either a burst error or
a random error causing a bit error rate of ≤ 0.5, the 24-bit CRC parity protects the message with an
error miss rate ≤ 2–24= 5.96×10–8.
The following generating polynomial is used for CRC parity:
g ( X ) = X 24 + X 23 + X 18 + X 17 + X 14 + X 11 + X 10 + X 7 + X 6 + X 5 + X 4 + X 3 + X + 1
User receivers must check the CRC parity of received messages. If there is a mismatch, the data in
that message should not be used.
84
IS-QZSS Ver. 1.6
5.4.3.2 Use of Messages
The method of using SAIF messages is specified below.
5.4.3.2.1 QZS Selection
When using SAIF messages, the SAIF message transmitted from a satellite that is currently in use
should be used. Either of the following two methods may be used when switching satellites.
(1) Parallel processing method: Before the changeover, the SAIF message being
transmitted by the successor satellite is received and processed independently from
the SAIF message being received from the current satellite. The changeover is
initiated when all of the data needed for positioning have been successfully received
from the successor satellite.
(2) Serial processing method: The user receiver’s positioning output must be
temporarily halted while changing satellites and all SAIF messages received from the
former satellite must be deleted. Following the changeover, the SAIF message
transmitted by the successor satellite is received and processed, and positioning
output is resumed when all of the data needed for positioning have been successfully
received from the successor satellite.
The parallel processing method allows positioning output to be maintained continuously. However,
at the time of changeover, both new and old SAIF messages must be processed in parallel. The
serial method simplifies message processing, but positioning output cannot be continuous and must
be stopped for several minutes. The serial method is similar to the processing performed following
receiver power-on.
5.4.3.2.2 Minimum Elevation Angle
The elevation angle of any satellite being used for augmentation data (via the QZSS SAIF message)
must be at least 5° above the horizon as viewed from the user position.
5.4.3.2.3 Selection of Positioning Satellites and Signals
Of the satellites for which QZSS provides augmentation data (via the SAIF message) and the
satellites actually indicated by the PRN mask, the satellites used for positioning by the user receiver
may be freely selected from among those that are above the specified 5° minimum elevation angle
as viewed from the user position.
Received QZS signals should be used in accordance with the following:
(1) The L1 frequency signals may be used as long as they are indicated by the PRN
mask.
(2) Other frequencies can be used in place of the L1C/A signal for the same satellite
after the Inter Signal Bias correction data in message type 56 have been applied.
However, the ionospheric propagation delay must be corrected as needed in
accordance with the frequency.
5.4.3.2.4 Numerical Expression
Each data included in the SAIF message are expressed by fixed-point number representation. The
specified bit sequence is transmitted from MSB to LSB and decimal point is located righthand of
LSB. The necessary data can be obtained by multiplied integer value by resolution specified for
each item. The two’s complement is used for expression of both plus and minus data.
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IS-QZSS Ver. 1.6
5.4.3.3 Message Content (SBAS Compatible Message)
5.4.3.3.1 Message Type 0 (Test Mode)
Message type 0 indicates that the L1-SAIF signal is in test mode. When a type 0 message has been
received, the receiver should delete all SAIF messages received up to that point, and SAIF messages
transmitted for the subsequent 60 seconds must also not be used.
5.4.3.3.2 Message Type 1 (PRN Mask)
Message type 1 contains a PRN mask. A PRN mask constitutes flag data that indicate a satellite for
which augmentation data will be provided. Of the satellites in PRN slots 1 ~ 210, PRN masks may
be set for up to 51 satellites.
Satellites for which PRN masks have been set are assigned PRN mask numbers in sequence starting
with the lowest PRN slot number. The range of PRN mask numbers is 1 ~ 51. In the second half of
message type 24, in the whole message types 25, 28 and 56 the target satellite is specified directly
by the PRN mask numbers 1 ~ 51. In message types 2 ~ 7 and in the first half of message type 24,
the correspondence between the correction data slot and the PRN mask number is established in
advance.
Following the 210-bit PRN mask, a 2-bit PRN mask issue number (IODP) is transmitted. This
number is incremented each time the PRN mask is updated (note that, since the IODP is only 2-bits,
after 3 comes 0). Other message types that reference the PRN mask number include IODP
corresponding to the PRN masks that should be used by receivers, so receivers should constantly
monitor the PRN masks matching the IODP and convert them to PRN slot numbers.
For QZSS, PRN mask updating differs from that specified in the Minimum Operational
Performance Standards (MOPS) (Applicable Document (5)) and is not necessarily conducted only
when a new satellite is launched or when a satellite goes out of service. In order to ensure the
efficient use of message bandwidth, the combination of satellites for augmentation will be updated
as needed. Other message types that reference the PRN mask number always require effective PRN
masks, so before the IODP for other messages is updated, a new PRN mask is transmitted by means
of message type 1. When a new PRN mask is received, the receiver retains both old and new PRN
masks for some time, and consideration must be given to ensuring the use of the appropriate PRN
mask until the IODP for other message types is updated.
When the IODP for a message type other than type 1 has been updated, the old PRN mask may be
deleted. In other words, different IODP are not retained just because the message type is different.
If the IODP for a message type has been updated, all of the IODP for other message types that are
transmitted are then updated.
If a message type that references a new IODP appears before a message type 1 containing a new
PRN mask has been received, that message type must not be used until a compatible PRN mask has
been received. Once a new compatible PRN mask has been received, those messages may be used
immediately.
In order to protect against message type 1 reception failures, when the PRN mask is updated,
message type 1 containing new PRN mask is transmitted at least four times over a period of 600
seconds before other message types that reference the new PRN mask are transmitted. In addition,
PRN mask updating is never performed more frequently than once per 30 minutes.
Repetitions
210
1
Table 5.4.3-2 Message Type 1: PRN Mask Data
Content
Number of bits
Resolution
Effective Range
Units
PRN mask
1
1
0~1
–
IODP
2
1
0~3
–
86
IS-QZSS Ver. 1.6
Table 5.4.3-3 PRN Slot Assignments to GNSS Satellites
PRN Slot
Satellite System
1 ~ 37
GPS
38 ~ 61
GLONASS
62 ~ 119
(Spare)
120 ~ 138
SBAS*
139 ~ 182
(Spare)
183
Quasi Zenith Satellite #1 L1-SAIF
184
Quasi Zenith Satellite #2 L1-SAIF
185
Quasi Zenith Satellite #3 L1-SAIF
186
Quasi Zenith Satellite #4 L1-SAIF
187
Quasi Zenith Satellite #5 L1-SAIF
188 ~ 192
Spare (for Quasi Zenith Satellite)
193
Quasi Zenith Satellite #1 L1C/A
194
Quasi Zenith Satellite #2 L1C/A
195
Quasi Zenith Satellite #3 L1C/A
196
Quasi Zenith Satellite #4 L1C/A
197
Quasi Zenith Satellite #5 L1C/A
198 ~ 202
Spare (for Quasi Zenith Satellite)
203 ~ 210
(Spare)
* SBAS: Satellite Based Augmentation System
5.4.3.3.3 Message Types 2 ~ 5 (Fast Correction & UDRE)
Message types 2 ~ 5 are used to transmit fast correction data. Each message has 13 correction data
slots, each corresponding to the following PRN mask numbers:
Message type 2
Message type 3
Message type 4
Message type 5
PRN mask no. 1 ~ 13
PRN mask no. 14 ~ 26
PRN mask no. 27 ~ 39
PRN mask no. 40 ~ 51
Slot 13 in message type 5 is not used. Each fast correction message type is transmitted only when
needed by the number of satellites specified in the PRN mask. In other words, message type 5 is
transmitted only when 40 or more satellites have been specified.
The 12-bit fast correction (FCi) is expressed as a two’s complement number (the MSB is the sign
bit) and has a resolution of 0.125 [m] for the range of [-256.000 [m], +255.750 [m]]. If this range
is exceeded, FCi = 255.875 [m] and UDREIi = 15 will be set so as to prohibit use of fast correction.
As message types 2 ~ 5 always have 13 correction slots, data for extra slots with no corresponding
PRN mask numbers should never be used. The FCi valid time (ti,0f) is the starting point for the
second epoch of GPS time that matches the first bit of the message block.
An "invalid" value for the fast correction value means that FCi = 255.875 or there is a time-out
status. If fast correction is invalid or UDREIi = 14 ~ 15, the associate satellite shall not be used for
position computation.
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IS-QZSS Ver. 1.6
The UDREIi included in message types 2 ~ 5 and 24 indicates the σ2i,UDRE corresponding to the fast
correction and is used to calculate the protection level. UDREIi = 15 indicates that the use of that
satellite is prohibited. UDREIi may also be transmitted by message type 6. In such cases, IODFj
(Issue of Data Fast Corrections) shows the timing by which this corresponds to the FCi that is
transmitted.
Message types 2 ~ 5 and 24 include a 2-bit fast correction updating number (IODFj). Here "j"
indicates the message type number (2 ~ 5); in the case of message type 24, it indicates the message
type (2 ~ 5) to which it corresponds. IODFj is used when calculating the degree of degradation of
the fast correction time change rate RRCi, and to establish the correspondence with the UDREIi
included in message type 6.
If there is no alert status for any of the satellites in the correction slots, the range of the IODFj
counter is 0 ~ 2 (incremented one by one; 2 is followed by 0). If an alert has been generated for one
or more of the satellites in the correction slots, the IODFj value is set to 3. If IODFj = 3 has been
transmitted, it indicates that the UDREIi included in that message type is used for all of the fast
corrections that are effective (i.e., not in time-out status) at that time.
If there are no more than 6 correction slots, message type 24 (fast & long-term corrections message)
is used in place of message types 2 ~ 5.
User algorithms for fast correction are in accordance with Section 6.4.2.2.
Repetitions
Table 5.4.3-4 Message Types 2 ~ 5: Fast Correction
Content
Number of bits
Resolution
Effective Range
Units
1
IODFj
2
1
0~3
–
1
IODP
2
1
0~3
–
13
FCi
12*
0.125
–256 ~ +255.75
M
13
UDREIi
4
(See Table 5.4.3-5)
*: Parameters so indicated shall be in two’s complement notation.
UDREIi
Table 5.4.3-5 UDRE value
σ i,UDRE [m2]
UDREIi
2
σ2i,UDRE [m2]
0
0.0520
8
2.5465
1
0.0924
9
3.3260
2
0.1444
10
5.1968
3
0.2830
11
20.7870
4
0.4678
12
230.9661
5
0.8315
13
2078.695
6
1.2992
14
Not Monitored
7
1.8709
15
Do Not Use
5.4.3.3.4 Message Type 6 (Integrity Data)
Message type 6 has been prepared to broadcast integrity data. The UDREIi for all satellites that are
targeted for augmentation (for which a PRN mask has been set) are transmitted together using the
format shown in Table 5.4.3-5 and Table 5.4.3-6. Message type 6 also includes an IODFj; an updated
number for the fast correction data is displayed for each of the 13 correction slots as in message
types 2 ~ 5.
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IS-QZSS Ver. 1.6
Repetitions
Table 5.4.3-6 Message Type 6: Integrity Data
Content
Number of bits
Resolution
Effective Range
Units
1
IODF2
2
1
0~3
―
1
IODF3
2
1
0~3
―
1
IODF4
2
1
0~3
―
1
IODF5
2
1
0~3
―
51
UDREIi
4
(See Table 5.4.3-5)
5.4.3.3.5 Message Type 7 (Fast Correction Degradation Factor)
Message type 7 is broadcast for maintaining compatibility, and described in Table 5.4.3-7.
Table 5.4.3-7 Message Type 7: Fast Correction Degradation Factor
Repetitions Content
Number of bits Resolution Effective Range
Units
1
System delay(tlat)
4
1
0 ~ 15
s
1
IODP
2
1
0~3
―
All zero
1
1
0
206
89
IS-QZSS Ver. 1.6
5.4.3.3.6 Message Type 10 (Degradation Parameter)
Message type 10 has been designed to provide a degradation factor used to calculate the protection
level. The parameters are as shown in Table 5.4.3-8.
Repetitions
Table 5.4.3-8 Message Type 10: Degradation Parameter
Content
Number of bits
Resolution
Effective Range
Units
1
Brrc
10
0.002
0 ~ 2.046
m
1
Cltc_lsb
10
0.002
0 ~ 2.046
m
1
Cltc_v1
10
0.05
0 ~ 51.15
mm/s
1
Iltc_v1
9
1
0 ~ 511
s
1
Cltc_v0
10
0.002
0 ~ 2.046
m
1
Iltc_v0
9
1
0 ~ 511
s
1
Cgeo_lsb
10
0.5
0 ~ 511.5
mm
1
Cgeo_v
10
0.05
0 ~ 51.15
mm/s
1
Igeo
9
1
0 ~ 511
s
1
Cer
6
0.5
0 ~ 31.5
m
1
Ciono_step
10
0.001
0 ~ 1.023
m
1
Iiono
9
1
0 ~ 511
s
1
Ciono_ramp
10
0.005
0 ~ 5.115
mm/s
1
RSSUDRE
1
1
0~1
―
1
RSSiono
1
1
0~1
―
1
Ccovariance
7
0.1
0 ~ 12.7
―
1
Cqzs_lsb
10
0.002
0 ~ 2.046
m
1
Cqzs_v1
10
0.05
0 ~ 51.15
mm/s
1
Iqzs_v1
9
1
0 ~ 511
s
1
Cqzs_v0
10
0.002
0 ~ 2.046
m
1
Iqzs_v0
9
1
0 ~ 511
s
1
IRI
3
1
0~4
―
1
Spare
30
―
―
―
90
IS-QZSS Ver. 1.6
5.4.3.3.7 Message Type 18 (IGP Mask)
As correction data for the ionospheric propagation delay, vertical delays corresponding to the
predetermined ionosphere grid points (IGP) are transmitted. Message type 18 is used to specify the
IGP that is currently the reference point for augmentation. If IGP mask is set to "1", the correction
data for the IGP is effective. However in the case that IGP mask is set to "0", the IGP is exempt
from correction. Message type 18 must be received before ionospheric propagation delay correction
is performed. Table 5.4.3-9 and Table 5.4.3-10 show the format and IGP content, respectively, for
message type 18.
The IGP is divided into 11 or 10 bands (it depends on IGP mask pattern) that are assigned band
numbers 0 ~ 10 or 0 ~ 9. For each band, as many as 201 IGPs are defined, corresponding to slots 1
~ 201. The order of IGP assignment for each band begins with slot number 1 in the southwest corner
and increments from south to north along the same longitude. Once the northern edge is reached, it
increments along the next eastward longitude from south to north and so on in sequence to assign
the IGP slot numbers from 1 ~ 201.
"Count of IGP bands" in Message Type 18 indicates total count of IGP bands for using. "IGP band
Number" means the IGP band corresponding to the IGP Mask information included in the Message.
IGPs for which IGP masks have been set are divided into blocks of 15 (up to 14 blocks) in sequence
by IGP mask number. IGP block 0 corresponds to IGP mask number 1 ~ 15, IGP block 1 corresponds
to IGP mask number 16 ~ 30 and so on.
The receiver need only collect correction data for the IGPs located at ± 20° in latitude and longitude
from its location. If the number of bands transmitted by message type 18 is 0, it indicates that
ionospheric propagation delay correction data are not provided.
Message type 18 includes a 2-bit IGP mask update number (IODI). This number is incremented
each time the IGP mask is updated (note that, since the IODI is only 2-bits, after 3 comes 0).
Message type 26 includes an IODI that corresponds to the IGP mask that should be used by the
receiver, so the receiver should constantly monitor the IGP mask that the IODI matches and convert
it into an IGP slot number.
IGP masks are almost never updated. Nevertheless, message type 26 always requires an effective
IGP mask, so a new IGP mask is transmitted by means of message type 18 before the IODI for
message type 26 is updated. When a new IGP mask is received, the receiver should retain both old
and new IGP masks for some time. It is important to use the appropriate IGP mask while waiting
for the IODI for message type 26 to be updated.
In the event that a new message type 26 referencing a new IODI has appeared before a message
type 18 containing a new IGP mask is received, that message type 26 must not be used until a
compatible IGP mask is received. Once a compatible IGP mask has been received, the message type
26 may be used immediately.
In order to prepare for message type 18 reception failures, when the IGP mask is updated, message
type 18 is broadcast at least four times over a period of 600 seconds before a message type 26
referencing the new IGP mask is transmitted. In addition, IGP mask updating is never performed
more frequently than once per hour.
Repetitions
Table 5.4.3-9 Message Type 18 Format: IGP Mask
Content
Number of bits Resolution Effective Range
Units
1
Count of IGP bands
4
1
0 ~ 11
―
1
IGP band Number
4
1
0 ~ 10
―
1
IODIk
2
1
0~3
―
IGP mask
1
―
0~1
―
IGP mask pattern
1
―
0~1
―
201
1
91
IS-QZSS Ver. 1.6
Table 5.4.3-10 Specification of IGP locations
(IGP mask pattern = 0)
Band
Longitude
Latitude
Slot No.
0
180W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N,85N
1 ~ 28
175W
55S,50S,45S,...,45N,50N,55N
29 ~ 51
170W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
52 ~ 78
165W
55S,50S,45S,...,45N,50N,55N
79 ~ 101
160W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
102 ~ 128
155W
55S,50S,45S,...,45N,50N,55N
129 ~ 151
150W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
152 ~ 178
145W
55S,50S,45S,...,45N,50N,55N
179 ~ 201
140W
85S,75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
1 ~ 28
135W
55S,50S,45S,...,45N,50N,55N
29 ~ 51
130W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
52 ~ 78
125W
55S,50S,45S,...,45N,50N,55N
79 ~ 101
120W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
102 ~ 128
115W
55S,50S,45S,...,45N,50N,55N
129 ~ 151
110W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
152 ~ 178
105W
55S,50S,45S,...,45N,50N,55N
179 ~ 201
100W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
1 ~ 27
95W
55S,50S,45S,...,45N,50N,55N
28 ~ 50
90W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N,85N
51 ~ 78
85W
55S,50S,45S,...,45N,50N,55N
79 ~ 101
80W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
102 ~ 128
75W
55S,50S,45S,...,45N,50N,55N
129 ~ 151
70W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
152 ~ 178
65W
55S,50S,45S,...,45N,50N,55N
179 ~ 201
60W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
1 ~ 27
55W
55S,50S,45S,...,45N,50N,55N
28 ~ 50
50W
85S,75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
51 ~ 78
45W
55S,50S,45S,...,45N,50N,55N
79 ~ 101
40W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
102 ~ 128
35W
55S,50S,45S,...,45N,50N,55N
129 ~ 151
30W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
152 ~ 178
25W
55S,50S,45S,...,45N,50N,55N
179 ~ 201
20W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
1 ~ 27
15W
55S,50S,45S,...,45N,50N,55N
28 ~ 50
10W
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
51 ~ 77
5W
55S,50S,45S,...,45N,50N,55N
78 ~ 100
1
2
3
4
92
IS-QZSS Ver. 1.6
5
6
7
8
9
0
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N,85N
101 ~ 128
5E
55S,50S,45S,...,45N,50N,55N
129 ~ 151
10E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
152 ~ 178
15E
55S,50S,45S,...,45N,50N,55N
179 ~ 201
20E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
1 ~ 27
25E
55S,50S,45S,...,45N,50N,55N
28 ~ 50
30E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
51 ~ 77
35E
55S,50S,45S,...,45N,50N,55N
78 ~ 100
40E
85S,75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
101 ~ 128
45E
55S,50S,45S,...,45N,50N,55N
129 ~ 151
50E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
152 ~ 178
55E
55S,50S,45S,...,45N,50N,55N
179 ~ 201
60E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
1 ~ 27
65E
55S,50S,45S,...,45N,50N,55N
28 ~ 50
70E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
51 ~ 77
75E
55S,50S,45S,...,45N,50N,55N
78 ~ 100
80E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
101 ~ 127
85E
55S,50S,45S,...,45N,50N,55N
128 ~ 150
90E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N,85N
151 ~ 178
95E
55S,50S,45S,...,45N,50N,55N
179 ~ 201
100E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
1 ~ 27
105E
55S,50S,45S,...,45N,50N,55N
28 ~ 50
110E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
51 ~ 77
115E
55S,50S,45S,...,45N,50N,55N
78 ~ 100
120E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
101 ~ 127
125E
55S,50S,45S,...,45N,50N,55N
128 ~ 150
130E
85S,75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
151 ~ 178
135E
55S,50S,45S,...,45N,50N,55N
179 ~ 201
140E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
1 ~ 27
145E
55S,50S,45S,...,45N,50N,55N
28 ~ 50
150E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
51 ~ 77
155E
55S,50S,45S,...,45N,50N,55N
78 ~ 100
160E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
101 ~ 127
165E
55S,50S,45S,...,45N,50N,55N
128 ~ 150
170E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
151 ~ 177
175E
55S,50S,45S,...,45N,50N,55N
178 ~ 200
60N
180W,175W,170W,...,165E,170E,175E
1 ~ 72
65N
180W,170W,160W,...,150E,160E,170E
73 ~ 108
70N
180W,170W,160W,...,150E,160E,170E
109 ~ 144
75N
180W,170W,160W,...,150E,160E,170E
145 ~ 180
93
IS-QZSS Ver. 1.6
10
85N
180W,150W,120W,...,90E,120E,150E
181 ~ 192
60S
180W,175W,170W,...,165E,170E,175E
1 ~ 72
65S
180W,170W,160W,...,150E,160E,170E
73 ~ 108
70S
180W,170W,160W,...,150E,160E,170E
109 ~ 144
75S
180W,170W,160W,...,150E,160E,170E
145 ~ 180
85S
170W,140W,110W,...,100E,130E,160E
181 ~ 192
(IGP mask pattern = 1)
Band
Longitude
Latitude
Slot No.
0
115E
15N,16N,17N,...,33N,34N,35N
1 ~ 21
116E
15N,16N,17N,...,33N,34N,35N
22 ~ 42
117E
15N,16N,17N,...,33N,34N,35N
43 ~ 63
118E
15N,16N,17N,...,33N,34N,35N
64 ~ 84
119E
15N,16N,17N,...,33N,34N,35N
85 ~ 105
120E
15N,16N,17N,...,43N,44N,45N
106 ~ 136
121E
15N,16N,17N,...,43N,44N,45N
137 ~ 167
122E
15N,16N,17N,...,43N,44N,45N
168 ~ 198
123E
15N,16N,17N,...,43N,44N,45N
1 ~ 31
124E
15N,16N,17N,...,43N,44N,45N
32 ~ 62
125E
15N,16N,17N,...,43N,44N,45N
63 ~ 93
126E
15N,16N,17N,...,43N,44N,45N
94 ~ 124
127E
15N,16N,17N,...,43N,44N,45N
125 ~ 155
128E
15N,16N,17N,...,43N,44N,45N
156 ~ 186
129E
15N,16N,17N,...,43N,44N,45N
1 ~ 31
130E
15N,16N,17N,...,48N,49N,50N
32 ~ 67
131E
15N,16N,17N,...,48N,49N,50N
68 ~ 103
132E
15N,16N,17N,...,48N,49N,50N
104 ~ 139
133E
15N,16N,17N,...,48N,49N,50N
140 ~ 175
134E
15N,16N,17N,...,48N,49N,50N
1 ~ 36
135E
15N,16N,17N,...,53N,54N,55N
37 ~ 77
136E
15N,16N,17N,...,53N,54N,55N
78 ~ 118
137E
15N,16N,17N,...,53N,54N,55N
119 ~ 159
138E
15N,16N,17N,...,53N,54N,55N
160 ~ 200
139E
15N,16N,17N,...,53N,54N,55N
1 ~ 41
140E
15N,16N,17N,...,53N,54N,55N
42 ~ 82
141E
20N,21N,22N,...,53N,54N,55N
83 ~ 118
142E
20N,21N,22N,...,53N,54N,55N
119 ~ 154
143E
20N,21N,22N,...,53N,54N,55N
155 ~ 190
144E
20N,21N,22N,...,53N,54N,55N
1 ~ 36
145E
20N,21N,22N,...,53N,54N,55N
37 ~ 72
1
2
3
4
5
94
IS-QZSS Ver. 1.6
6
7
8
9
146E
20N,21N,22N,...,53N,54N,55N
73 ~ 108
147E
20N,21N,22N,...,53N,54N,55N
109 ~ 144
148E
20N,21N,22N,...,53N,54N,55N
145 ~ 180
149E
20N,21N,22N,...,53N,54N,55N
1 ~ 36
150E
20N,21N,22N,...,53N,54N,55N
37 ~ 72
151E
25N,26N,27N,...,53N,54N,55N
73 ~ 103
152E
25N,26N,27N,...,53N,54N,55N
104 ~ 134
153E
25N,26N,27N,...,53N,54N,55N
135 ~ 165
154E
25N,26N,27N,...,53N,54N,55N
166 ~ 196
100E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
1 ~ 27
105E
55S,50S,45S,...,45N,50N,55N
28 ~ 50
110E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
51 ~ 77
115E
55S,50S,45S,...,45N,50N,55N
78 ~ 100
120E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
101 ~ 127
125E
55S,50S,45S,...,45N,50N,55N
128 ~ 150
130E
85S,75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
151 ~ 178
135E
55S,50S,45S,...,45N,50N,55N
179 ~ 201
140E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
145E
55S,50S,45S,...,45N,50N,55N
28 ~ 50
150E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
51 ~ 77
155E
55S,50S,45S,...,45N,50N,55N
160E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
101 ~ 127
165E
55S,50S,45S,...,45N,50N,55N
128 ~ 150
170E
75S,65S,55S,50S,45S,...,45N,50N,55N,65N,75N
151 ~ 177
175E
55S,50S,45S,...,45N,50N,55N
178 ~ 200
110E
17.5N,22.5N,27.5N,32.5N,37.5N
1~5
112.5E
15N,17.5N,20N,...,35N,37.5N,40N
6 ~ 16
115E
17.5N,22.5N,27.5N,32.5N,37.5N
17 ~ 21
117.5E
15N,17.5N,20N,...,35N,37.5N,40N
22 ~ 32
120E
17.5N,22.5N,27.5N,32.5N,37.5N,42.5N
33 ~ 38
122.5E
15N,17.5N,20N,...,40N,42.5N,45N
39 ~ 51
125E
17.5N,22.5N,27.5N,32.5N,37.5N,42.5N
52 ~ 57
127.5E
15N,17.5N,20N,...,40N,42.5N,45N
58 ~ 70
130E
17.5N,22.5N,27.5N,32.5N,37.5N,42.5N,47.5N,52.5N
71 ~ 78
132.5E
15N,17.5N,20N,...,50N,52.5N,55N
79 ~ 95
135E
17.5N,22.5N,27.5N,32.5N,37.5N,42.5N,47.5N,52.5N
96 ~ 103
137.5E
15N,17.5N,20N,...,50N,52.5N,55N
104 ~ 120
140E
17.5N,22.5N,27.5N,32.5N,37.5N,42.5N,47.5N,52.5N
121 ~ 128
142.5E
15N,17.5N,20N,...,50N,52.5N,55N
129 ~ 145
145E
17.5N,22.5N,27.5N,32.5N,37.5N,42.5N,47.5N,52.5N
146 ~ 153
95
1 ~ 27
78 ~ 100
IS-QZSS Ver. 1.6
147.5E
20N,22.5N,25N,...,50N,52.5N,55N
154 ~ 168
150E
22.5N,27.5N,32.5N,37.5N,42.5N,47.5N,52.5N
169 ~ 175
152.5E
25N,27.5N,30N,...,50N,52.5N,55N
176 ~ 188
155E
27.5N,32.5N,37.5N,42.5N,47.5N,52.5N
189 ~ 194
5.4.3.3.8 Message Type 24 (Fast/Long-term Correction)
Message type 24 includes the parameters for Fast Correction and Long-term Correction.
Message type 24 may be used when the correction slot in message types 2 ~ 5 can only
accommodate up to 6 items. Specifically, this occurs when the number of satellites subject to
augmentation is 1 ~ 6, 14 ~ 19, 27 ~ 32 or 40 ~ 45.
The first half of message type 24 contains the fast correction data in six slots. The 0 ~ 3 values for
block ID correspond to message types 2 ~ 5, respectively, and specify the range of the PRN mask
number to which the fast corrections in the six correction slots correspond. The contents of the
parameters and the method of use for the fast corrections is exactly the same as that for message
types 2 ~ 5 (see section 5.4.3.3.3).
The last half of message type 24 can accommodate half of the content of message type 25 (one
partial message). This allows long-term correction data for one or two satellites to be provided
(please refer to section 5.4.3.3.9 for contents, etc.).
Table 5.4.3-11 Message Type 24 (Fast & Long-term Corrections)
Repetitions Content
Number of bits
Resolution
Effective Range
Units
12*
m
6
FCi
6
UDREIi
4
1
2
1
0~3
―
2
1
0~3
―
1
IODP
Fast correction
block ID
IODFj
2
1
0~3
―
1
Reserved
4
-
-
-
1
Partial message
1
106
0.125
–256 ~ +255.75
(See Table 5.4.3-5)
(See Table 5.4.3-13)
*: Parameters so indicated shall be in two’s complement notation.
5.4.3.3.9 Message Type 25 (Long-Term Correction)
Message type 25 is broadcast to provide corrections for the clock and ephemeris long-term error.
Target satellites and signals for correction are L1C/A signal from GPS satellites & QZS-1, L1
Standard Accuracy Signal from GLONASS and L1-SAIF (Message Type 58) signal from QZS-1.
For GPS satellites, the clock and ephemeris that are the target for augmentation using QZS message
type 25 must be calculated using the L1C/A navigation message (NAV message). The CNAV (Civil
Navigation: L2C and L5 Navigation) and CNAV2 messages must not be used.
Message type 25 is made up of two partial messages. Each partial message has exactly the same
format consisting of 106 bits. The partial message may include correction data for two satellites
(velocity code = 0) or correction data for one satellite (velocity code = 1). In the former case
(velocity code = 0), the message includes only corrections for clock offset and satellite position
error. In the latter case, the message also includes the rates of change for clock offset and satellite
positioning errors. Therefore, a message type 25 can accommodate long-term correction data for 2
~ 4 satellites.
Table 5.4.3-13 specifies the format for the two types of partial message corresponding to velocity
code values of "0" and "1". The velocity codes for the two partial messages included in a single
message of message type 25 can be different value.
96
IS-QZSS Ver. 1.6
The PRN mask number (1 ~ 51) is defined by the PRN mask provided by message type 1. The
IODP for the PRN mask must match. If the long-term correction data are invalid, "0" is set for the
PRN mask number. Unlike message types 2 ~ 5, the positioning satellites augmented by message
type 25 may not appear in sequential order, and there is no guarantee that the long-term corrections
for each satellite will appear with the same frequency. Long-term correction data for satellites with
rapidly changing long-term errors will be repeated with a greater frequency than the data of satellites
with long-term errors that change more slowly.
Repetitions
2
Table 5.4.3-12 Message Type 25: Long-Term Correction
Content
Number of bits
Resolution
Effective Range
Partial message
106
Units
(See Table 5.4.3-13)
Table 5.4.3-13 Partial message format of Message Type 25
(Velocity code= 0)
Repetitions
1
2
Content
Number of bits
Resolution
Effective Range
Units
Velocity code(= 0)
1
1
0
―
PRN mask no.
6
1
0 ~ 51
―
IODi**
8
1
0 ~ 255
―
δxi
9
*
0.125
±32
m
δyi
9*
0.125
±32
m
δz i
9*
0.125
±32
m
-22
s
δai , f0
10
1
IODP
2
1
0~3
―
1
Spare
1
―
―
―
*
2
-31
±2
(Velocity code= 1)
Repetitions
1
1
Content
Number of bits
Resolution
Effective Range
Units
Velocity code(= 1)
1
1
1
―
PRN mask no.
6
1
0 ~ 51
―
IODi**
8
1
0 ~ 255
―
δxi
11*
0.125
±128
m
δyi
*
11
0.125
±128
m
δz i
11*
0.125
±128
m
δai , f0
11*
2-31
±2-21
s
-11
±0.0625
m/s
i
δx
8
i
δy
8*
2-11
±0.0625
m/s
δzi
8
*
-11
±0.0625
m/s
δa i , f1
8*
2-39
±2-32
s/s
1
Epoch time(ti,LT)
13
16
0 ~ 86384
s
1
IODP
2
1
0~3
―
*
2
2
* Parameters so indicated are in two’s complement notation.
**The Issue of Data (IODi) value corresponds to the 8-bit Ephemeris IOD value (IODE) in L1C/A signal from GPS satellites &
QZS-1, Ephemeris received time (tr) for GLONASS satellites and Epoch time (t0,Q/60) in L1-SAIF signal from QZS-1.
97
IS-QZSS Ver. 1.6
An 8-bit Issue of Data value (IOD) is included in the long-term correction data. IOD specifies the
ephemeris which user receivers must apply to calculation. The considerations for using are as
follows.
(a) In the case of GPS satellites and QZS-1 (L1C/A signal)
For L1C/A signal from GPS satellites & QZS-1, user receivers must only use navigation messages
containing IODC and IODE values that match this number (in the case of IODC, applied to the
last 8 bits).
(b) In the case of GLONASS satellites
For GLONASS satellites, IOD indicates the range of the receiving period of ephemeris data for
user receivers. Upper 5 bit of IOD means validity period (tGLONASS_V), and lower 3 bits means
delay time (tGLONASS_L) (see Table 5.4.3-14). User receivers must use the receiving time of
ephemeris data (tr) which satisfy the following relations. (tLT: Transmitting time in MT 24 or 25,
tr: Receiving time of ephemeris data.)
t LT − t GLONASS _ L − t GLONASS _ V ≤ t r ≤ t LT − t GLONASS _ L
Table 5.4.3-14 Information to specify the ephemeris of GLONASS
Item
Number of bits
Effective Range
Resolution
Unit
Validity period(tGLONASS_L)
5
30 ~ 960
30
s
Delay time(tGLONASS_L)
3
0 ~ 120
30
s
(c) In the case of QZS-1(L1-SAIF Signal)
For L1-SAIF signal from QZS-1, user receivers must use the navigation message which has same
IOD with the epoch time (t0,Q/60) transmitted in MT 58 (QZS ephemeris)
If these parameters are updated, it indicates that the navigation message of GPS satellites,
GLONASS satellites, and QZS-1 has been updated; however, the receiver should continue to use
the old navigation message (for which the Long Term Correction message specified). If a message
type 24 or 25 that matches the new navigation message IOD has been received, the receiver should
switch to the new navigation message for positioning.
It would take some time for all user receivers to receive the new navigation message. For this reason,
even if the IOD for the GPS navigation message has been updated, the long-term correction data
IOD provided by message type 24 and 25 will not be updated for at least two minutes.
User algorithms for long term correction are in accordance with Section 6.4.2.1.
5.4.3.3.10 Message Type 26 (Ionospheric Delay & GIVE)
Message type 26 provides receivers with augmentation data corresponding to the IGP defined in
Table 5.4.3-9. This includes the ionospheric vertical delay (at the L1 frequency) and its accuracy.
For more information on the content of the data, see Table 5.4.3-15. The correspondence between
Grid Ionosphere Vertical Error Index (GIVEI) and σ2GIVE is as shown in Table 5.4.3-16.
A single message of type 26 provides 15 items of augmentation data for a given IGP. A band number
(0 ~ 9) and a block ID (0 ~ 13) are also included to specify the corresponding IGP. The band number
corresponds to the band numbers in Table 5.4.3-10. Block 0 corresponds to IGP mask numbers 1 ~
15 (numbers 1 ~ 15 of the IGPs for which the IGP mask number is set to "1"). Block 1 corresponds
to IGP mask numbers 16 ~ 30. Augmentation data located at slot numbers that exceed the number
of IGPs indicated by the IGP mask data are invalid.
98
IS-QZSS Ver. 1.6
The 9-bit ionospheric vertical delay parameter has a resolution of 0.125 [m] in the effective range
of [0, 63.750 [m]]. A vertical delay of 63.875 [m] ("111111111"(B)) indicates "use prohibited". In
other words, a vertical delay exceeding 63.750 [m] cannot be expressed (In this case, GIVEIi = 15
[Not Monitored]).
User algorithms for Ionospheric Delay correction are in accordance with Section 6.4.2.3.
Table 5.4.3-15 Message Type 26: Ionospheric Delay Correction
Repetitions Content
Number of bits Resolution Effective Range
Units
1
IGP band ID
4
1
0 ~ 10
―
1
IGP block ID
Ionospheric vertical
delay
GIVEIi
4
1
0 ~ 13
―
9
0.125
0 ~ 63.750
m
1
IODIk
2
1
0~3
―
1
Spare
7
―
―
―
15
GIVEIi
4
(See Table 5.4.3-16)
Table 5.4.3-16 GIVEI Value
σ2GIVE,i [m2]
GIVEIi
σ2GIVE,i [m2]
0
0.0084
8
0.6735
1
0.0333
9
0.8315
2
0.0749
10
1.1974
3
0.1331
11
1.8709
4
0.2079
12
3.3260
5
0.2994
13
20.7870
6
0.4075
14
187.0826
7
0.5322
15
Not Monitored
5.4.3.3.11 Message Type 28 (Clock-ephemeris Covariance)
Message type 28 is transmitted to provide the covariance matrix that expresses the correlation
between clock and ephemeris error. Using this matrix makes it possible to estimate the degree of
degradation of correction data at the receiver position.
Table 5.4.3-17 specifies the content and format of message type 28. The PRN mask number is the
same as that for message types 24 and 25. Message type 28 includes covariance matrices for two
satellites. However, there is only one IODP, and the same PRN mask data are used for both satellites.
99
IS-QZSS Ver. 1.6
Table 5.4.3-17 Message Type 28: Clock – Orbit Covariance
Repetitions Content
Number of bits
Resolution
Effective Range
1
2
Units
IODP
2
1
0~3
―
PRN mask no.
6
1
1 ~ 51
―
Scale factor
3
1
0~7
―
E1,1
9
1
0 ~ 511
―
E2,2
9
1
0 ~ 511
―
E3,3
9
1
0 ~ 511
―
E4,4
9
1
0 ~ 511
―
E1,2
10*
1
±512
―
E1,3
10*
1
±512
―
E1,4
10*
1
±512
―
E2,3
10*
1
±512
―
E2,4
10*
1
±512
―
E3,4
10*
1
±512
―
*: Parameters so indicated shall be in two’s complement notation.
5.4.3.3.12 Message Types 62 (Internal Test Message) and 63 (Null Message)
Message type 63 is the Null Message and is always transmitted as a string of 212 zeroes. Message
type 62 is used only for internal testing purposes, and its content is not defined.
Repetitions
212
Table 5.4.3-18 Message Type 63 (Null Message)
Content
Number of bits
Resolution
Effective Range
All zeroes
1
1
100
0
Units
―
IS-QZSS Ver. 1.6
5.4.3.3.13 Message Type 12 (Timing Information)
Message type 12 is transmitted to provide Timing Information. Table 5.4.3-19 specifies the content
of message type 12.
Table 5.4.3-19 Message Type 12: Timing Information
Repetitions Content
Number of bits Resolution Effective Range
1
Reserved
137
–
–
1
GLONASS Flag
1
1
0~1
1
δ ai,GLONASS
24
1
Reserved
50
2
-31
–
±2
Units
–
8
–
–
s
–
An "invalid" value for δ ai,GLONASS value means that GLONASS Flag = 0. Please refer to section
6.4.2.1 for the use of δ ai,GLONASS.
5.4.3.4 Message Content (SBAS Non-Compatible Message)
5.4.3.4.1 Message Type 52 (TGP Mask)
As correction data for the tropospheric delay, Zenith Tropospheric Delay Offset (ZTDO) at the
tropospheric grid point (TGP) is transmitted.
Message type 52 is used to specify the TGPs that provide ZTDOs. Table 5.4.3-20 specifies the
content of message type 52.
Message type 52 includes 2 bit TGP issue mask update number (IODT). This number is incremented
each time the TGP Mask is updated. (Note: after 3 comes 0)
Message type 53 (see section 5.4.3.4.2) contains the same IODT as message type52.
The correction data should be applied with confirmation of the correspondence of IODT between
message type 52 and 53 in receivers. All the received correction data could be applied by retaining
un-updated mask data until receiving all the messages type 52 and 53 coming after IODT update.
The TGPs which provide ZTDOs are specified by using 210 slots in message 52. Table 5.4.3-21
shows the TGP number and its corresponding longitude and latitude. Slot of which position is the
same number as TGP number which provides ZTDO is set as ‘1’. Message type 52 is transmitted at
least 1 time over a period of 600 seconds.
Repetitions
1
210
Table 5.4.3-20 Message Type 52: TGP Mask
Content
Number of bits
Resolution
Effective Range
Units
IODT
2
1
0~3
–
TGP Mask
1
1
0~1
–
101
IS-QZSS Ver. 1.6
Table 5.4.3-21 Specification of TGP locations (1/2)
North
TGP
East
North
TGP
Latitude
Number Longitude Latitude
Number
TGP
Number
East
Longitude
East
Longitude
North
Latitude
1
144.5
44.0
36
138.5
36.0
71
145.0
44.0
2
144.5
43.5
37
137.5
36.5
72
145.0
43.5
3
142.5
45.0
38
139.0
35.0
73
145.0
43.0
4
144.0
43.5
39
138.0
35.5
74
143.0
44.5
5
142.5
44.5
40
137.0
36.0
75
144.5
43.0
6
144.0
43.0
41
139.5
33.5
76
143.0
44.0
7
143.0
43.5
42
137.5
35.0
77
142.0
44.5
8
142.5
43.5
43
136.5
35.5
78
143.5
43.0
9
142.0
43.5
44
136.0
35.5
79
143.0
43.0
10
141.5
43.5
45
135.5
35.5
80
142.5
43.0
11
143.0
42.0
46
135.0
35.5
81
142.0
43.0
12
141.5
42.5
47
134.5
35.5
82
141.5
43.0
13
140.5
43.0
48
136.0
34.0
83
141.0
43.0
14
141.5
41.0
49
135.0
34.5
84
141.0
42.0
15
141.0
41.5
50
133.5
35.5
85
140.5
42.0
16
142.0
40.0
51
135.0
34.0
86
141.0
41.0
17
141.0
40.5
52
133.5
35.0
87
140.0
42.0
18
140.0
41.5
53
142.0
26.5
88
141.5
40.0
19
141.5
39.5
54
134.0
34.0
89
140.5
40.5
20
141.0
39.5
55
133.0
34.5
90
140.0
40.5
21
140.5
39.5
56
132.0
35.0
91
141.5
39.0
22
140.0
39.5
57
133.5
33.5
92
141.0
39.0
23
141.0
38.0
58
133.0
33.5
93
140.5
39.0
24
140.5
38.0
59
132.5
33.5
94
140.0
39.0
25
140.0
38.0
60
131.5
34.0
95
141.0
37.5
26
139.5
38.5
61
131.5
33.5
96
140.5
37.5
27
140.5
37.0
62
131.0
33.5
97
139.5
38.0
28
140.0
37.0
63
130.5
33.5
98
139.0
38.0
29
139.0
37.5
64
130.0
33.5
99
140.5
36.5
30
140.5
36.0
65
131.5
32.0
100
139.5
37.0
31
139.5
36.5
66
130.5
32.5
101
138.5
37.5
32
138.5
37.0
67
129.5
33.0
102
140.0
36.0
33
140.0
35.5
68
131.0
31.5
103
139.0
36.5
34
139.0
36.0
69
130.5
31.0
104
138.0
37.0
35
137.0
37.5
70
128.0
26.5
105
139.5
35.5
102
IS-QZSS Ver. 1.6
Table 5.4.3-21 Specification of TGP locations (2/2)
North
TGP
East
North
TGP
Latitude
Number Longitude Latitude
Number
TGP
Number
East
Longitude
East
Longitude
North
Latitude
106
137.5
37.0
141
145.5
43.5
176
138.0
36.5
107
139.0
35.5
142
144.0
44.0
177
137.0
37.0
108
138.0
36.0
143
142.0
45.5
178
138.5
35.5
109
137.0
36.5
144
143.5
44.0
179
137.5
36.0
110
138.5
35.0
145
142.0
45.0
180
136.5
36.5
111
137.5
35.5
146
143.5
43.5
181
138.0
35.0
112
136.5
36.0
147
142.5
44.0
182
137.0
35.5
113
138.0
34.5
148
142.0
44.0
183
136.0
36.0
114
137.0
35.0
149
143.5
42.5
184
137.5
34.5
115
136.5
35.0
150
143.0
42.5
185
137.0
34.5
116
136.0
35.0
151
142.5
42.5
186
136.5
34.5
117
135.5
35.0
152
142.0
42.5
187
136.0
34.5
118
135.0
35.0
153
141.0
42.5
188
135.5
34.5
119
134.0
35.5
154
140.5
42.5
189
134.5
35.0
120
135.5
34.0
155
140.0
42.5
190
136.0
33.5
121
134.0
35.0
156
141.5
40.5
191
134.5
34.5
122
135.5
33.5
157
140.5
41.0
192
133.0
35.5
123
134.0
34.5
158
142.0
39.5
193
134.5
34.0
124
133.0
35.0
159
141.0
40.0
194
133.5
34.5
125
134.5
33.5
160
140.5
40.0
195
132.5
35.0
126
133.5
34.0
161
140.0
40.0
196
134.0
33.5
127
132.5
34.5
162
141.5
38.5
197
133.0
34.0
128
132.0
34.5
163
141.0
38.5
198
132.5
34.0
129
131.5
34.5
164
140.5
38.5
199
132.0
34.0
130
133.0
33.0
165
140.0
38.5
200
131.0
34.5
131
132.5
33.0
166
141.0
37.0
201
131.0
34.0
132
132.0
33.0
167
140.0
37.5
202
130.5
34.0
133
131.5
33.0
168
139.5
37.5
203
129.5
34.5
134
131.0
33.0
169
138.5
38.0
204
131.5
32.5
135
130.5
33.0
170
140.0
36.5
205
131.0
32.5
136
129.5
33.5
171
139.0
37.0
206
130.0
33.0
137
131.0
32.0
172
140.5
35.5
207
131.5
31.5
138
130.0
32.5
173
139.5
36.0
208
130.5
32.0
139
129.0
33.0
174
138.5
36.5
209
130.5
31.5
140
131.0
30.5
175
140.0
35.0
210
129.0
28.0
103
IS-QZSS Ver. 1.6
5.4.3.4.2 Message Type 53 (Tropospheric Delay Correction)
By the message type 53, ZTDO at TGP which is specified by TGP mask data of message type 52 is
transmitted to the receivers. Table 5.4.3-20 shows the data content. One message type 53 contains
2bits IODT, 3 bits TGP block ID, and ZTDOs at 34 TGPs.
Total number of TGPs which provide ZTDOs is obtained by the mask data of message type 52.
Message type 53 with TGP block ID from 0 to an integer n is provided, where the total number of
TGPs to provide ZTDOs is larger than 34n and no more than 34(n+1).
The message type 53 with TGP block ID n contains ZTDOs at from (34n+1)th to 34(n+1)th TGPs
in the same order as in the effective TGP mask data.
ZTDO which is provided 6 bits per 1 point has a resolution of 0.01[m] in the effective range of [–
0.32, +0.30[m]]. "011111"(B) indicates that ZTDO of corresponding TGP has not been provided.
Table 5.4.3-22 Message type 53: Zenith Tropospheric Delay Correction
Repetitions Content
Number of bits
Resolution
Effective Range
Units
1
IODT
2
1
0~3
–
1
TGP block ID
3
1
0~6
–
34
ZTDO
6*
0.01
–0.32 ~ +0.30
m
–
–
–
1
Reserved
3
*: Parameters shall be in two’s complement notation.
5.4.3.4.3 Message Type 54 (Atmospheric Delay Correction)
Content has not been defined yet.
5.4.3.4.4 Message Type 55 (Atmospheric Delay Correction)
Content has not been defined yet.
5.4.3.4.5 Message Type 56 (Inter Signal Bias Correction Data)
Message type 56 provides the internal signal group delay with respect to the L1C/A signal for the
timing at which the multiple signals broadcast by the corresponding GPS or QZSS satellite are
actually transmitted from the phase center of the satellite antenna. The PRN mask number has the
same meaning as that for message type 25. When multiple signals are used together, the data in this
message can be used.
Table 5.4.3-23 Message Type 56: Inter Signal Bias Correction Data
Repetitions Content
Number of bits Resolution Effective Range
Units
1
5
IODP
2
1
0~3
―
PRN mask no.
6
1
1 ~ 51
―
ISCL1C_L1CA
9*
0.05
±12.8
m
ISCL2C_L1CA
9
*
0.05
±12.8
m
ISCL5_L1CA
9*
0.05
±12.8
m
ISCL1P_L1CA
9*
0.05
±12.8
m
*: Parameters so indicated shall be in two’s complement notation.
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IS-QZSS Ver. 1.6
5.4.3.4.6 Message Type 57 (Orbit Data)
Content has not been defined yet.
5.4.3.4.7 Message Type 58 (QZS Ephemeris)
Message type 58 is transmitted to provide QZS Ephemeris data. The satellite position is provided
in the form of coordinates in the Japan satellite navigation Geodetic System (JGS) orthogonal
coordinate system in reference epoch t0,Q.
Item
Table 5.4.3-24 QZS Ephemeris Data
Number of bits
Range
Resolution
Notes
t0,Q
8
0 ~ 10740 [s]
60 [s]
URA
4
0-15
–
XQ
26*
±42949.673 [km]
1.28 [m]
Epoch time
Positioning
indicator
X coordinate
YQ
26*
±42949.673 [km]
1.28 [m]
Y coordinate
ZQ
26*
±42949.673 [km]
1.28 [m]
Z coordinate
X Q
Y
24*
±4194.304 [m/s]
0.5 [mm/s]
Velocity
24*
±4194.304 [m/s]
0.5 [mm/s]
Velocity
24*
±4194.304 [m/s]
0.5 [mm/s]
Velocity
5*
±32 [μm/s]
2 [μm/s]
Acceleration
Q
Z Q
X
Q
YQ
Z
5*
±32 [μm/s]
2 [μm/s]
Acceleration
5*
±32 [μm/s]
2 [μm/s]
Acceleration
aQf0
22*
±1.953 [ms]
2-30 [s]
Clock correction
aQf1
*
±3.725 [ns/s]
-40
Clock correction
Q
13
2
[s/s]
accuracy
Total
212
*: Parameters so indicated shall be in two’s complement notation.
5.4.3.4.8 Message Type 59 (QZSS Almanac Data)
Content has not been defined yet.
5.4.3.4.9 Message Type 60 ((Regional information/maintenance schedule))
Content has not been defined yet.
5.4.3.5 L1-SAIF+ Message
L1-SAIF+ Message is the message that Satellite Positioning Research and Application Center
(SPAC) will transmit for the applications demonstration. For L1-SAIF+ Message, the message type
40 ~ 51 is defined as L1-SAIF+ Unique Message in addition to SBAS compatible message in
Section 5.4.3.3, SBAS non- compatible message in Section 5.4.3.4.
The detailed information are referenced in Interface Specification (Applicable Documents (6)) to
be established by SPAC.
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IS-QZSS Ver. 1.6
5.5 L2C signal
5.5.1 RF characteristics
5.5.1.1 Signal configuration
In accordance with Section 5.1.
5.5.1.2 Carrier wave properties
In accordance with Section 5.1.
5.5.1.3 Code properties
5.5.1.3.1 Code attributes
Same as sections 3.2.1.4, 3.2.1.5 and 3.3.2.4 of Applicable Document (1). However, the PRN code
number is as described in Section 5.1.1.11.1 of this document.
5.5.1.3.2 Non-standard code
In the event of a problem with QZSS, a non-standard code (NSC) is transmitted. This is done to
protect users by ensuring that they do not receive or use erroneous navigation data.
5.5.2 Message
5.5.2.1 Message configuration
Each message of the L2C signal (DL2C) comprises 300 [bits]: 276 [bits] of data and 24 parity check
bits. Each message is broadcast for 12 [seconds]. This message configuration is the same as Section
30.3.2 in Applicable Document (1).
5.5.2.1.1 Preamble
The 8-bit preamble added to the beginning of each message is the same as in Section 30.3.3 of
Applicable Document (1).
5.5.2.1.2 PRN number
The 6-bit PRN number added after the preamble in each message is the last 6 [bits] of the PRN
number for the QZS transmitting the corresponding message.
5.5.2.1.3 Message type ID
The 6-bit message type ID added after the PRN number in each message signifies the data contained
in that message. Table 5.5.2-1 specifies the message content for each of the individual message
types. For more information, see Section 5.5.2.2. The different types of messages are transmitted at
intervals not to exceed the Maximum Transmit Intervals specified in Table 5.5.2-2.
QZSs may transmit the same message type with different timing.
106
IS-QZSS Ver. 1.6
Table 5.5.2-1 Definitions of message types for Navigational Message DL2C
Message type ID Message content
Notes
10
Health, URA, Ephemeris 1
11
Ephemeris 2
When Message type ID (MTID)
is 46: Retransmit of ionospheric
parameters broadcasted by GPS,
however ISC broadcasted by
GPS is not retransmitted by
QZSS
When MTID is 47: Retransmit of
GPS reduced Almanac
30, 46
SV clock, ionospheric parameter, ISC
31, 47*
SV clock, reduced Almanac
32
SV clock, EOP (Earth Orientation Parameter)
33, 49
SV clock, UTC parameter
34
SV clock, performance enhancement data
35, 51
SV clock, GGTO (GPS GNSS Time Offset )
37, 53
SV clock, Midi Almanac
12*, 28
Reduced Almanac
13
SV clock performance enhancement data
When MTID is 49: Retransmit of
GPS UTC parameters
Transmitted as needed
When MTID is 51: Retransmit of
GGTO broadcasted by GPS
When MTID is 53: Retransmit of
GPS Midi Almanac
When MTID is 28: Retransmit of
GPS reduced Almanac
Transmitted as needed
14
Ephemeris performance enhancement data
Transmitted as needed
15
Text
Transmitted as needed
* QZS-1 at current MCS does not be transmitting the data of Type 12 and 47 because the contents of them are same with those
of type 31 and 28.
107
IS-QZSS Ver. 1.6
Table 5.5.2-2 Maximum Transmit Intervals for Navigational Message DL2C
Maximum
Message Data
Message Type ID
Notes
Transmit Interval
Ephemeris
10,11
30-35, 37, 46, 47,
49, 51, 53
30
48 seconds
46
*2
31 or 12*1
20 minutes (*3)
Reduced Almanac of GPS
(GPS retransmitting)
Midi Almanac of QZSS
47 or 28*1
*2,*3
37
120 minutes (*3)
Midi Almanac of GPS
(GPS retransmitting)
EOP
53
*2,*3
32
30 minutes (*3)
UTC parameters
UTC
parameters
retransmitting)
DC data
33
288 seconds
49
*2
34 or 13 & 14
30 minutes (*2,*3)
35
288 seconds (*3)
51
*2,*3
15
As needed
SV clock
ISC, ionospheric parameter
Ionospheric parameter
(GPS retransmitting)
Reduced Almanac of QZSS
(GPS
GGTO (GPS-QZSS Time
Offset)
GGTO (GPS-GNSS (Galileo
and GLONASS) Time Offset)
(GPS retransmitting)
Text
48seconds
288 seconds
When MTID= 46, ISC
would not be transmitted.
All necessary SV data must
be transmitted
All necessary SV data must
be transmitted
All necessary SV data must
be transmitted
All necessary SV data must
be transmitted
Only when performance
enhancement
data
are
effective
*1 QZS-1 at current MCS does not be transmitting the data of Type 12 and 47 because the contents of them are same with those
of type 31 and 28.
*2 We will not define the maximum transmit interval for GPS retransmitting parameters and GPS DC data.
*3 Optional (interval applies if/when broadcast).
5.5.2.1.4 TOW count
The 17-bit TOW (Time of Week) count that follows the message type ID in each message indicates
the time at the beginning of the next message, which is six times that value. This is the same as
Section 30.3.3 in Applicable Document (1).
5.5.2.1.5 "Alert" flag
The 1-bit "Alert" flag that follows the TOW count in each message is in accordance with Section
5.1.2.1.3.
5.5.2.1.6 FEC and parity algorithm
The CNAV data will be encoded with FEC. The algorithm for encoding is the same as in Section
3.3.3.1.1 of Applicable Document (1).
The 24-bit parity code added after the 300-bit message. The parity algorithm is the same as in
Section 30.3.5 of Applicable Document (1).
5.5.2.2 Message content
With the exception of the list in Section 8.1.2, the content of the message is the same as in Applicable
Document (1).
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IS-QZSS Ver. 1.6
5.5.2.2.1 Ephemeris data and health for message types 10 and 11
5.5.2.2.1.1 Content of Ephemeris data and health for message types 10 and 11
Message types 10 and 11 include the Ephemeris data (such as that shown in Table 5.5.2-3) for the
corresponding satellite. The general content is the same as in Section 30.3.3.1.1 of Applicable
Document (1).
Table 5.5.2-3 Definition of Ephemeris parameters for Navigational Message DL2C
Parameter
Definition
10
WNn
Week Number
10
L1/L2/L5 Health
10
top
10
URAED index
L1, L2 and L5 signal health
Data predict time of week (seconds
into week)
ED Accuracy index
10
11
toe
Difference from GPS definition
Ephemeris epoch (seconds into week)
10
∆A
10

A
10
∆n0
10
∆ n0
Difference from semi major axis at toe
In the case of QZS, indicates
difference with 42,164,200 [m]
Change rate in semi major axis
Difference from mean motion
calculation at toe
Change rate from mean motion
calculation
10
M0-n
Mean anomaly at toe
10
en
Eccentricity
10
ωn
11
Ω0-n
11
I0-n
11
∆ Ω
11
io-n-DOT
11
Cis-n
11
Cic-n
11
Crs-n
11
Crc-n
11
Cus-n
11
Cuc-n
Argument of perigee
Longitude of ascending node at the
beginning of the week
Orbit inclination at toe
Rate of Right ascension of ascending
node (RAAN) difference from
reference value*1
Change rate in orbit inclination
Amplitude of the sine harmonic
correction term to the angle of
inclination
Amplitude of the cosine harmonic
correction term to the angle of
inclination
Amplitude of the sine harmonic
correction term to the orbit radius
Amplitude of the cosine harmonic
correction term to the orbit radius
Amplitude of the sine harmonic
correction term to the argument of
latitude
Amplitude of the cosine harmonic
correction term to the argument of
latitude
* Relative to
−9

Ω
REF = −2.6 × 10
In the case of GPS, indicates
difference with 26,559,710 [m]
For QZSS, no restrictions on
parameter range (for GPS : 0.0 ~
0.03)
[semi-circles/second] (same value with GPS).
109
IS-QZSS Ver. 1.6
(1) Transmission Week Number
Bits 39 ~ 51 in message type 10 constitute a binary expression for the 8192 remainder of the
current GPS Week Number. This is the same as in Section 30.3.3.1.1.1 of Applicable Document
(1).
(2) Signal health (L1/L2/L5)
The three single bits from bit 52 to bit 54 in message type 10 indicate the health of the L1, L2
and L5 signals, respectively, transmitted by the corresponding satellite.
The value for the L1 signal is "1" in the event that there is a problem with one or more of the
L1C/A, L1-SAIF or L1C signals.
0
1
No problems with signal
Problem with signal exists or signal cannot be used
These bit indices are compared to the monitoring results at the present time for the
corresponding satellite. The details are in accordance with Section 5.1.2.1.3.
Health data are also present in message types 12, 31 and 37. The data in message type 10 are
uploaded at a different time, so the data may differ from that for the transmission satellites of
other messages and other satellite data.
(3) Data Predict Time of week: top
Bits 55-65 in message type 10 indicate the data predict time of week (top). The top term provides
the epoch time of week of the state estimate utilized for the prediction of satellite ephemeris
parameters. This is the same as in Section 30.3.3.1.3 of Applicable Document (1).
(4) Elevation Dependent Accuracy indicator: URAED index
Bits 66-70 in message type 10 indicate the Elevation Dependent (ED) Component of accuracy
indicator. For more information, see Section 5.1.2.1.3.2.
(5) Ephemeris data epoch: toe
Bits 71 ~ 81 in message type 10 and bits 39 ~ 49 in message type 11 indicate the epoch for
Ephemeris data. This is the same as in Figure 30-1 and Table 30-I of Applicable Document (1).
(6) Ephemeris data
After the URAED index in message type 10, the Ephemeris data (shown in Table 5.5.2-3) for
the corresponding satellite are transmitted. In the data, ΔA represents the value of the SemiMajor Axis in the context of toe (A(toe)) minus 42,164,200 [m]:
∆ A (t oe ) = A (t oe ) − 42,164,200 [m]
Other values are the same as in Table 30-I of Applicable Document (1).
5.5.2.2.1.2 Characteristics of Ephemeris Data Parameters for Message Types 10 and 11
With the exception of those items shown in the previous section (5.5.2.2.1.1), the parameter
characteristics for message types 10 and 11 (number of bits, LSB scale factor, data range and
units) are the same as those shown in Table 30-I of Applicable Document (1).
Bit allocation for message types 10 and 11 is the same as in Figures 30-1 and 30-2 of Applicable
Document (1). However, Integrity Status Flag and L2C Phasing Flag were added in Figure 30-1
of Applicable Document (1), QZS-1 at current MCS did not adopt (fixed at "0"(B)).
5.5.2.2.1.3 Message Types 10 and 11: User Algorithms for Satellite Positioning
In accordance with Section 6.3.5.
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5.5.2.2.2 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: SV Clock Correction
Parameters
5.5.2.2.2.1 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: Content of SV Clock
Parameters
Message types 30, 31, 32, 33, 34, 35 37, 46, 47, 49, 51 and 53 all contain SV clock parameters
for the corresponding satellite such as those shown in Table 5.5.2-4. For an overview, see Section
30.3.3.2.1 of Applicable Document (1).
Table 5.5.2-4 Definition of SV clock parameters for Navigational Message DL2C
Parameter
Definition
Difference from GPS definition
toc
SV clock parameter epoch (seconds into week)
URANED0 index
NED Accuracy index
URANED1 index
NED Accuracy change index
URANED2 index
NED Accuracy change rate index
af0-n
SV clock bias correction term
af1-n
SV clock drift correction term
af2-n
SV clock drift rate correction term
(1) Data predict time of accuracy indicator for SV clock parameters (top)
Bits 39 ~ 49 indicate the data predict time of week (top) for the accuracy indicator for the SV
clock parameters.
(2) Non-Elevation Dependent accuracy indicator (URANED index)
Bits 50 ~ 60 include the parameter needed to determine the Non- Elevation Dependent (NED)
User Range Accuracy (URANED). Details are in accordance with Section 5.1.2.1.3.2.
(3) SV clock parameter epoch (toc)
Bits 61 ~ 71 constitute the SV clock parameter epoch toc.
(4) SV clock parameter
The SV clock parameter for the corresponding satellite, shown in Table 5.5.2-4, will be
transmitted. The user algorithm is the same as in Section 20.3.3.3.3.1 of Applicable Document
(1). However, certain parts of the definition are different; for more information, see Section
6.3.2.
5.5.2.2.2.2 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: Characteristics of SV
Clock Parameters
With the exception of those items shown in the previous section (Section 5.5.2.2.2.1), the
parameter characteristics for message types 30, 31, 32, 33, 34, 35, 37, 46, 47, 49, 51 and 53 (clock
correction parameter number of bits, LSB scale factor, data range and units) are the same as those
shown in Table 30-III of Applicable Document (1).
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5.5.2.2.2.3 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: User Algorithm for SV
Clock Correction Data
(1) Calculation of Non-Elevation Dependent User Range Accuracy: URANED calculation.
The algorithm used to determine the detailed user positioning accuracy (Non-Elevation
Dependent (NED) component) (IAURANED) expressed by URANED index is the same as in
Section 30.3.3.2.4 of Applicable Document (1).
For more information about how to use URANED, see Section 3.1.2.1.3. For more information
about the content of URANED, see Section 5.1.2.1.3.
(2) Calculation of SV clock offset using SV clock parameters
As this is an estimate by the Control Segment by means of the L1C/A signal and the L2C signal
code measurement, there are additions to the SV clock correction algorithm for one-signal users
and 2-signal (L1C/A and L2C) users. See Section 6.3.2 for details.
5.5.2.2.3 Message Type 30, 46: Ionospheric Parameter, Group Delay Differential Correction
Parameter and etc.
In addition to the SV clock parameters (Section 5.5.2.2.2), message type 30 includes the ionospheric
parameters like those shown in Table 5.5.2-5, the internal signal group delay differential correction
parameters shown in Table 5.5.2-6 and the ephemeris related parameter shown in table 5.5.2-7. For
more information regarding the content of these parameters, see Section 30.3.3.3.1 of Applicable
Document (1).
Ionospheric parameters in Message type 46 are rebroadcast of parameters broadcasted by GPS.
Since Group Delay Correction parameters broadcasted by GPS is NOT rebroadcasted by QZSS,
bits 128 to 192 in message type 46 can NOT be used.
Table 5.5.2-5 Definition of ionospheric parameters for Navigational Message DL2C
Parameter
Definition
Difference from GPS definition
α0
Ionospheric parameter α0 for Klobuchar model
Coefficient optimized for Japan & environs
α1
Ionospheric parameter α1 for Klobuchar model
Coefficient optimized for Japan & environs
α2
Ionospheric parameter α2 for Klobuchar model
Coefficient optimized for Japan & environs
α3
Ionospheric parameter α3 for Klobuchar model
Coefficient optimized for Japan & environs
β0
Ionospheric parameter β0 for Klobuchar model
Coefficient optimized for Japan & environs
β1
Ionospheric parameter β1 for Klobuchar model
Coefficient optimized for Japan & environs
β2
Ionospheric parameter β2 for Klobuchar model
Coefficient optimized for Japan & environs
β3
Ionospheric parameter β3 for Klobuchar model
Coefficient optimized for Japan & environs
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Table 5.5.2-6 Group Delay Differential Correction Parameters (TGD, ISC) for Navigational
Message DL2C
Parameter
Definition
Difference from GPS definition
TGD
Group Delay Differential Correction Term
between LCQZSS*1.and.L1C/A
Inter-Signal Correction Term for L1C/A (between
L1C/A and L1C/A) (Broadcasting value is 0.0)
Inter-Signal Correction Term for L2C (between
L1C/A and L2C)
Inter-Signal Correction Term for L5I5 (between
L1C/A and L5I5)
Inter-Signal Correction Term for L5Q5 (between
L1C/A and L5Q5)
LCGPS*2 and L1P(Y) for GPS
ISCL1C/A
ISCL2C
ISCL5I5
ISCI5Q5
L1P(Y) – L1C/A for GPS
L1P(Y) – L2C for GPS
L1P(Y) – L5I5 for GPS
L1P(Y) – L5Q5 for GPS
*1 LCQZSS: LCQZSS is the ionospheric error free linear combination of the L1C/A and L2C signals for QZSS
*2 LCGPS: LCGPS is the ionospheric error free linear combination of the L1P(Y) and L2P(Y) signals for GPS
Table 5.5.2-7 Ephemeris related parameter (WNop) for Navigational Message DL2C
Parameter
Definition
Difference from GPS definition
WNop
Data Predict Week Number at the data predict
time of week (top)
–
(1) Ionospheric parameters
This section provides the ionospheric parameters used by one-signal users (who use only the
L1, L2 or L5 signal) when they use an ionospheric model to calculate the ionospheric delay.
These parameters are specialized to fit the geographic area shown in Figure 4.1.5-1.
User algorithms for one-signal users are in accordance with Sections 6.3.4 and 6.3.8.
These parameters use data from the past 24 hours (Maximum) and are updated at least once per
day except "ionospheric maximum periods".
The number of bits, scale factor, range and units are the same as in Section 20.3.3.5.2.5 and
Table 20-X of Applicable Document (1).
(2) Estimating the L1-L2 group delay difference
Group delay differential correction terms TGD, ISCL1C/A and ISCL2C for users of only one signal
(L1C/A, L1C, L2C or L5) and L1/L2 are contained in bits 128 ~ 166 of message type 30. Of
these, ISCL1C/A has a value of zero. The numbers of bits, scale factor, range and units are the
same as Table 30-IV of Applicable Document (1). However bit string for each parameter is
"1000000000000", it indicates that the group delay differential correction parameter cannot be
used. The relevant algorithms are shown in Sections 6.3.3 and 6.3.4.
(3) Data Predict Week Number
Bits 257 ~ 264 of Message Type 30 indicate the Data Predict Week Number (WNOP) to which
the Data Predict Time of Week (top) is referenced (see section 5.5.2.2.2.1(1)). The WNOP term
consists of eight bits which is a modulo 256 binary representation of the GPS week number to
which the top is referenced.
5.5.2.2.4 Message Types 31, 12, 37, 47, 28 and 53: Almanac Data
QZS Almanac data are provided by message types 31, 12 and 37. The Reduced Almanac is provided
by message type 31 or 12, and the Midi Almanac is provided by message type 37. The PRN number
for these message types indicates the last 6 bits of the QZS PRN.
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Almanac data for other satellite positioning systems are provided by message types 47, 28 and 53.
The Reduced Almanac is provided by message type 47 or 28, and the Midi Almanac is provided by
message type 53. Of the PRN numbers for these message types, numbers 1 ~ 32 are for GPS
satellites. However according to Applicable document (1), PRN No. for GPS satellites are extended
to 1 ~ 63, it would not be supported by QZS-1 at current MCS.
The Reduced Almanac for satellites is broadcast by a single satellite in a shorter interval than the
Midi Almanac.
Table 5.5.2-8 Definition of Midi Almanac parameters for Navigational Message DL2C
Parameter
Definition
Difference from GPS definition
WNa-n
toa
PRN no.
L1/L2/L5 Health
e
δi

Ω
A
Ω0
GPS Week Number at the time of Midi Almanac
generation
Midi Almanac epoch (second in week)
When the message type number is 37, it indicates
that this value is for a QZS satellite and represents
the last 6 bits of the QZS PRN number.
When the message type number is 53, it indicates
that this value is the PRN value for a GPS satellite
(PRN No. = 1 ~ 32).
L1, L2 and L5 signal health
Eccentricity (offset from the nominal QZS
eccentricity of 0.06)
Offset from the reference QZS orbit inclination
(0.25 [semi-circles]) (Offset from 0.25 [semicircle]= 45 [deg])
Change rate in right ascension of ascending node
(RAAN)
Square root of Semi-Major Axis
ω
Longitude of ascending node at the beginning of
the week
Argument of perigee
M0
Mean anomaly
af0
Bias term for SV clock
af1
Drift term for SV clock
114
For GPS, PRN number is
extended to 1 ~ 63, but it is not
supported by QZS-1 at current
MCS.
In the case of GPS, "e" means
eccentricity value itself.
In the case of GPS, the reference
inclination is 0.3 [semi-circles],
which represents 54 [deg].
IS-QZSS Ver. 1.6
Table 5.5.2-9 Definition of Reduced Almanac parameters for Navigational Message DL2C
Parameter
Definition
Difference from GPS definition
WNa-n
toa
PRN no.
δA
Ω0
GPS Week Number at the time of Reduced
Almanac generation
Reduced Almanac epoch (second in week)
When the message type number is 31 or 12, it
indicates that this value is for a QZS satellite and
represents the last 6 bits of the QZS PRN
number.
When the message type number is 47 or 28, it
indicates that this value is the PRN value for a
GPS satellite (PRN No.= 1 ~ 32)
Offset from the nominal QZS Semi-Major Axis
of 42,164,200 [m]
Longitude of ascending node at the beginning of
the week
Φ0
Argument of latitude (= M0 + ω)
L1/L2/L5 Health
L1, L2 and L5 signal health
Implicit eccentricity (0.075 in the case of QZS)
(precondition for above parameter)
Fixed at –0.0111 [semi-circles], the offset from
the reference QZS orbit inclination of 0.25
for
above
[semi-circles]
(precondition
parameter)
Implicit Argument of Perigee (270 [deg] in
QZS-1)(Precondition for above parameters)
(e)
(δi)
(ω)
115
For GPS, PRN number is
extended to 1 ~ 63, but it is not
supported by QZS-1 at current
MCS.
In the case of GPS, indicates the
offset from 26,559,710 [m]
Based on the assumption that ω=
270 [deg]
0 in the case of GPS
In the case of GPS, fixed at
+0.0056 [semi-circles], the offset
from 0.3 [semi-circles]
0 [deg] in case of GPS
IS-QZSS Ver. 1.6
5.5.2.2.4.1 Almanac Reference Week Number
Bits 39 ~ 51 in message types 12 and 28 and bits 128 ~ 140 in message types 31and 37 (and 47
and 53) indicate the Week Number (WNa-n) that serves as a reference for the Almanac reference
time (toa) (see Section 20.3.3.5.2.2 of Applicable Document (1)). WNa-n is made up of 13 bits and
is expressed by the modulo-8192 GPS Week Number (see Section 6.3.6) that serves as a reference
for toa.
5.5.2.2.4.2 Almanac reference time
Bits 52–59 in message type 12 (and 28) and bits 141 ~ 148 in message types 31 and 37 (and also
47 and 53) indicate the Almanac reference time (toa).See Section 20.3.3.5.2.2 of Applicable
Document (1).
5.5.2.2.4.3 Satellite PRN number
The first 6 bits in the 31-bit Reduced Almanac included in message types 31 and 12 (and also 47
and 28) constitute the corresponding satellite’s PRN. In the case of message types 31 and 12, the
PRN constitutes the last 6 bits of the QZS PRN. In the case of message types 47 and 28, the PRN
number 1 to 32 is a GPS PRN number.
If the Almanac data is not effective, the value of the PRN Number is set to "111111"(B) as in
Applicable Document (1). In this event, the remainder of the rest of 22 bits in the data block shall
be filler bits, i.e., alternating ones and zeros beginning with one, and the 3-Bit-Health is set to
"111"(B) (cf. Section 5.5.2.2.4.4). When the PRN number is 0 (PRN No. = "000000"(B)), it means
that the data packet includes dummy data for GPS. But in the case of QZSS at current MCS, it
means that the MCS could not acquire the data and the 22 bits in data packets are all "0"(B)s for
QZS-1.
There is a PRN in bits 149 ~ 154 of the Midi Almanac included in message type 37 (and 53). In
the case of message type 37, the PRN constitutes the last 6 bits of the QZS PRN. In the case of
message type 53, the PRN is a GPS PRN (PRN No. = 1 ~ 32).
5.5.2.2.4.4 Signal health (L1/L2/L5)
The three 1-Bit-Health indicators – bits 155, 156 and 157 in message type 37 (and 53) and bits
29, 30 and 31 in the Reduced Almanac in message types 31 and 12 (and also 47 and 28) relate to
the L1, L2 and L5 signals for the satellite corresponding to the PRN number.
Their meaning is covered in Section 5.1.2.1.3.
5.5.2.2.4.5 Midi Almanac data content
Message type 37 (and 53) provides the Almanac for the satellite with the PRN number shown in
the message.
The number of bits, scale factor, range and units are the same as in Table 30-V of Applicable
Document (1). However, the QZS eccentricity differs from that of GPS and is provided relative
to the reference values as noted below. For inclination, reference inclination value for QZSS is
different from that of GPS as noted below.
(1) Eccentricity
(a) In the case of QZSS:
ea = 0.06 + enav
(b) In the case of GPS: ea = 0.00 + enav
Reference in accordance with Applicable Document (1)
ea :
Actual eccentricity value
enav :
Eccentricity value included in navigation message
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(2) Inclination
(a) In the case of QZSS:
ia = 0.25 + δ i [semi-circle]
(b) In the case of GPS: ia = 0.3 + δ i [semi-circle]
Reference in accordance with Applicable Document (1)
i: Actual inclination value
δi:Inclination value included in navigation message
For the user algorithm, see Section 6.3.6.
The Midi Almanac data for the QZS are updated at least once every 6 days. The velocity
calculated by the Midi Almanac data is accurate within 30 [m/s].
5.5.2.2.4.6 Content of Reduced Almanac Data
Message type 31 and 12 (and also 47 and 28) contain multiple reduced Almanac data values.
Semi major axis and inclination are provided relative to reference values as shown below.
(1) Semi-Major Axis
(a) For QZSS: A = 42,164,200 [m] + δA
(b) For GPS: A = 26,559,710 [m] + δA
Reference in accordance with Applicable Document (1)
(2) Eccentricity
(a) For QZSS: e = 0.075
(b) For GPS: e = 0.0
Reference in accordance with Applicable Document (1)
(3) Orbit Angle of Elevation
(a) For QZSS: i = 43 [deg]
(b) For GPS: i = 55 [deg]
Reference in accordance with Applicable Document (1)
(4) Time change rate for right ascension of ascending node (RAAN)
 = －8.7 × 10 −10 [semi-circles/seconds]
(a) For QZSS: Ω
 = −2.6 × 10 −9 [semi-circles/seconds]
(b) For GPS: Ω
Reference in accordance with Applicable Document (1)
(5) Implicit Argument of Perigee
(a) For QZSS: ω = 270 [deg]
(b) For GPS: ω =
0 [deg]
The number of bits, LSB scale factor, range and units are the same as in Table 30-VI of Applicable
Document (1).
For the user algorithm, see Section 6.3.6.
The Reduced Almanac data for the QZS are updated at least once every 3 days. The velocity
calculated by the Reduced Almanac data is accurate within 350 [m/s].
5.5.2.2.5 Message type 32: Earth orientation parameter (EOP)
The Earth rotation parameter is included in message type 32. The definition, number of bits, scale
factor, range, units, LSB, user algorithm, etc., for this parameter are all the same as table 30-VII in
Applicable Document (1).
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5.5.2.2.6 Message type 33, 49: UTC Parameters
The UTC parameters are included in message type 33 (and 49). When the Message Type = 33, the
UTC parameters transmitted by the QZS is needed to link GPS time to UTC (NICT). When the
Message Type = 49, those are gathered by receiving GPS signals at QZS Monitor Stations and rebroadcasted to link GPS time to UTC (USNO). The numbers of bits, scale factor, range, units, LSB,
user algorithm, etc., for this parameter are almost the same as Section 30.3.3.6 in Applicable
Document (1). However, the bit length of WNLSF (Leap second reference Week Number) for QZS1, 13 bits.
5.5.2.2.7 Message Type 34, 13, 14: Differential Correction Data (DC Data)
Differential correction data (DC data) are included in message types 34, 13 and 14. These
parameters provide users with correction terms for SV clock parameters and Ephemeris data
transmitted by other satellites. DC data is divided into packets that comprise a 34-bit SV clock error
correction (CDC) parameter and a 92-bit Ephemeris error correction (EDC) parameter. CDC and
EDC data are paired, and users must use the CDC and EDC pair corresponding to the same top-D
and tOD.
Message type 34 includes the CDC and EDC for one satellite. Message type 13 includes the CDC
data for six satellites, while message type 14 includes the EDC data for two satellites.
A DC Type indicator "0" indicates that the corresponding correction parameters should be applied
to CNAV data, while "1" indicates that the corrections should be applied to the navigation message
for the L1C/A signal.
The content of the data packets is the same as Section 30.3.3.7 in Applicable Document (1). The
content is shown in Table 5.5.2-10.
The bit definition, number of bits, scale factor and unit for DC data are the same as Table 30-XI in
Applicable Document (1).
If the DC data is not effective, the value of the PRN Number is set to "11111111"(B) as Section
30.3.3.7.2.3 in Applicable Document (1). In this case, DC type indicator is set to "0".
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Table 5.5.2-10 Definition of parameters for DC data for Navigational Message DL2C
Parameter
Definition
Difference from GPS definition
top-D
tOD
DC Type indicator
Prediction time of week for DC data
(second in week)
Reference time of week for DC data
(second in week)
1: For DLIC/A message
δ af0
0: For DL2C message
PRN no. (range 0 ~ 255) for satellite for
which performance enhancement data will
be applied
1 ~ 32 if target is GPS; 193 ~ 197 if target
is QZSS
Bias term for SV clock
δ af1
Drift correction term for SV clock
UDRA index
User Differential Range Accuracy (UDRA)
PRN no.
For GPS, PRN number is
extended to 1 ~ 63, but it is not
supported by QZS-1 at current
MCS.
index
∆α
α correction term for Ephemeris parameter
∆β
β correction term for Ephemeris parameter
∆γ
γ correction term for Ephemeris parameter
∆i
Correction term for orbit inclination
Correction term for right ascension of
ascending node (RAAN)
Correction term for Semi-Major Axis
∆Ω
∆A
．
UDRA index
UDRA rate index
5.5.2.2.7.1 Differential Correction (DC) data
DC data include the following. For more information regarding the use of DC data, see Section
3.1.2.1.3.4.
(1) Time of DC data estimation (top-D)
"top-D" indicates the time (seconds into week) at which DC data were estimated. This value is
the same as Section 30.3.3.7.2.1 in Applicable Document (1).
(2) DC data epoch (tOD)
"tOD" indicates the epoch (seconds into week) for DC data. This value is the same as Section
30.3.3.7.2.2 in Applicable Document (1).
(3) Satellite PRN identification
The 8-bit PRN specifies the satellite for which the corresponding DC data set is to be used.
When PRN is 1-32, it indicates GPS; when PRN is 193-197, it indicates QZSS. According to
Applicable document (1), PRN No. for GPS satellites are extended to 1 ~ 63, but it would not
be supported by QZS-1 at current MCS.
If the bit values are all set to "1" (PRN No. = "11111111"(B)), then there are no DC data in the
data block. This is the same as Section 30.3.3.7.2.3 in Applicable Document (1) in the sense
that the remaining data consist of alternating bit values of "1"(B) and "0"(B).
(4) Use of CDC data
Same as Section 30.3.3.7 in Applicable Document (1). For more information, see Section
6.3.9.2.
(5) Use of EDC data
Same as Section 30.3.3.7 in Applicable Document (1). For more information, see Section
6.3.9.2.
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5.5.2.2.7.2 DC Data Accuracy
．
The User Differential Range Accuracy, UDRAop-D, and its time derivative, UDRA, indicate the
positioning accuracy after DC data have been applied to the SV clock parameter and Ephemeris
data.
The bit definition, number of bits, etc., and user algorithm are the same as Figure 30-16 and
Section 30.3.3.7.5 in Applicable Document (1).
．
For more information regarding the use of UDRAop-D and UDRA, see Section 3.1.2.1.3.5.
5.5.2.2.8 Message type 35, 51: GPS/GNSS time offset: GGTO
Message type 35 (and 51) is the parameter used to adjust GPS time to match other GNSS (QZSS,
Galileo and GLONASS) times.
The bit definition, number of bits, scale factor (LSB), range and units are all the same as Figure 308 and Table 30-XI in Applicable Document (1).
In the case of Message Type ID= 51, the message is GPS retransmitting.
Table 5.5.2-11 Definition of GPS GNSS Time Offset (GGTO) parameters for Navigational
Message DL2C
Parameter
Definition
tGGTO
Seconds into GGTO reference week
WNGGTO
GGTO reference Week Number
GNSS ID
See Section 5.5.2.2.8.1
A0GGTO
GPST bias term associated with other GNSS
system time
GPST drift term associated with other GNSS
system time
GPST drift rate term associated with other
GNSS system time
A1GGTO
A2GGTO
Difference from GPS definition
In the case of GPS, "011"(B)
means "spare".
5.5.2.2.8.1 GNSS - ID
Bits 157-159 in message type 35 define the other satellite positioning systems to which data
offsets with respect to GPS are applied. The definitions of these three bits are as follows.
000:
001:
010:
011:
100 ~ 111:
Data cannot be used
Galileo
GLONASS
QZSS
Spare
5.5.2.2.8.2 GPS/GNSS Time Offset
The algorithm used to determine GPS GNSS Time Offset (GGTO) is the same as Section
30.3.3.8.1 in Applicable Document (1).
However, the QZS SV clock parameter already uses GPST as the reference, so the time offset
value for GPS and QZSS (GQTO) is always zero.
In the case of Message type ID = 18, it is rebroadcast of GPS message and the validity period of
the GGTO should be 1 day as a minimum (refer to section 30.3.3.8 in Applicable document (1)).
5.5.2.2.9 Message Types 15: Text Messages
Text messages are transmitted using the 29 8-bit ASCII characters in message type 15. The bit
definition, number of bits, etc., is the same as Figure 30-14 in Applicable Document (1).
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5.6 L5 signal
5.6.1 RF characteristics
5.6.1.1 Signal configuration
In accordance with Section 5.1.
L5
Navigation
Message
Outer FEC
Coder
300bits/6s
(CRC 24)
Inner FEC
½ Coder
600bits/6s
(7 Convolution)
(276bits)
10-symbol
NH Code
10bits-Length/10ms
(1ksps)
CNAV
(100sps)
XI
PRN
as Ranging Code
(10.23Mcps)
10230chips-Length/1ms
20-symbol
NH Code
XQ
L5I
L5Q
20bits-Length/20ms
(1ksps)
Figure 5.6.1-1 L5 Signal Structure
5.6.1.2 Carrier wave properties
In accordance with Section 5.1.
5.6.1.3 Code properties
5.6.1.3.1 Code attributes
Same as sections 3.2.1, 3.3.2 and 6.3.4 of Applicable Document (2). However, the PRN code
number is as described in Section 5.1.1.11.1 of this document.
5.6.1.3.2 Non-standard code
In the event of a problem with QZSS, a non-standard code (NSC) is transmitted. This is done to
protect users by ensuring that they do not receive or use erroneous navigation data.
5.6.2 Message
5.6.2.1 Message configuration
Each message of the L5 signal (DL5) comprises 300 [bits]: 276 [bits] of data and 24 parity check bits.
Each message is broadcast for 6 [seconds]. This message configuration is the same as Section 20.3.2
in Applicable Document (2).
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IS-QZSS Ver. 1.6
5.6.2.1.1 Preamble
The 8-bit preamble added to the beginning of each message is the same as Section 20.3.3 in
Applicable Document (2).
5.6.2.1.2 PRN number
The 6-bit PRN number added after the preamble in each message is the last 6 bits of the PRN
number for the QZS transmitting the corresponding message.
5.6.2.1.3 Message type ID
The 6-bit message type ID added after the PRN number in each message signifies the data contained
in that message. Table 5.6.2-1 specifies the message content for each of the individual message
types. For more information, see Section 5.6.2.2. The different types of messages are transmitted at
intervals not to exceed the Maximum Transmit Intervals specified in Table 5.6.2-2.
QZSs may transmit the same message type with different timing.
Table 5.6.2-1 Definitions of message types for Navigational Message DL5
Message type ID
Message content
10
Health, URA, Ephemeris 1
11
Ephemeris 2
Notes
When Message type ID (MTID)
is 46: Retransmit of ionospheric
parameters broadcasted by GPS,
however ISC broadcasted by
GPS is not retransmitted by
QZSS
When MTID is 47: Retransmit of
GPS reduced Almanac
30, 46
SV clock, ionospheric parameter, ISC
31, 47*
SV clock, Reduced Almanac
32
SV clock, EOP (Earth Orientation Parameter)
33, 49
SV clock, UTC parameter
34
SV clock, performance enhancement data
35, 51
SV clock, GGTO (GPS GNSS Time Offset )
37, 53
SV clock, Midi Almanac
12*, 28
Reduced Almanac
13
SV clock performance enhancement data
When MTID is 49: Retransmit of
GPS UTC parameters
Transmitted as needed
When MTID is 51: Retransmit of
GGTO broadcasted by GPS
When MTID is 53: Retransmit of
GPS Midi Almanac
When MTID is 28: Retransmit of
GPS reduced Almanac
Transmitted as needed
14
Ephemeris performance enhancement data
Transmitted as needed
15
Text
Transmitted as needed
* QZS-1 at current MCS does not be transmitting the data of Type 12 and 47 because the contents of them are same with those
of type 31 and 28.
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IS-QZSS Ver. 1.6
Table 5.6.2-2 Maximum Transmit Intervals for Navigational Message DL5
Message Type ID Maximum
Message Data
Notes
Transmit Interval
Ephemeris
10,11
30-35, 37, 46, 47,
49, 51, 53
30
24 seconds
46
*2
Reduced Almanac of QZSS
31 or 12*1
10 minutes (*3)
Reduced Almanac of GPS
(GPS retransmitting)
47 or 28*1
*2, *3
Midi Almanac of QZSS
37
60 minutes
53
*2
32
15 minutes (*3)
33
144 seconds
49
*2
34 or 13 & 14
15
(*2,*3)
35
144 seconds (*3)
51
*2,*3
15
As needed
SV clock
ISC, ionospheric parameter
Ionospheric parameter
(GPS retransmitting)
Midi Almanac of GPS
(GPS retransmitting)
EOP
UTC parameters
UTC
parameters
retransmitting)
(GPS
DC data
GGTO (GPS-QZSS Time
Offset)
GGTO (GPS-GNSS (Galileo
and GLONASS) Time Offset)
(GPS retransmitting)
Text
24 seconds
144 seconds
minutes
When MTID= 46, ISC
would not be broadcasted.
All necessary SV data must
be transmitted
All necessary SV data must
be transmitted
All necessary SV data must
be transmitted
All necessary SV data must
be transmitted
Only when performance
enhancement
data
are
effective
*1 QZS-1 at current MCS does not be transmitting the data of Type 12 and 47 because the contents of them are same with those
of type 31 and 28.
*2 We will not define the maximum transmit interval for GPS retransmitting parameters and GPS DC data.
*3 Optional (interval applies if/when broadcast)
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IS-QZSS Ver. 1.6
5.6.2.1.4 TOW count
The 17-bit TOW (Time of Week) count that follows the message type ID in each message indicates
the time at the beginning of the next message, which is six times that value. This is the same as
Section 20.3.3 in Applicable Document (2).
5.6.2.1.5 "Alert" flag
The 1-bit "Alert" flag that follows the TOW count in each message is in accordance with Section
5.1.2.1.3.
5.6.2.1.6 FEC and parity algorithm
The CNAV data will be encoded with FEC. The algorithm for encoding is the same as in Section
3.3.3.1.1 of Applicable Document (2).
The 24-bit parity code added after the 300-bit message. The parity algorithm is the same as in
Section 20.3.5 of Applicable Document (2).
5.6.2.2 Message content
With the exception of the list in Section 8.1.2, the content of the message is the same as in Applicable
Document (2).
5.6.2.2.1 Ephemeris data and health for message types 10 and 11
5.6.2.2.1.1 Content of Ephemeris data and health for message types 10 and 11
Message types 10 and 11 include the Ephemeris data (such as that shown in Table 5.6.2-3) for the
corresponding satellite. The general content is the same as Section 20.3.3.1 in Applicable
Document (2).
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IS-QZSS Ver. 1.6
Table 5.6.2-3 Definition of Ephemeris parameters for Navigational Message D L5
Parameter
Definition
10
WNn
Week Number
10
L1/L2/L5 Health
10
top
10
URAED index
L1, L2 and L5 signal health
Data predict time of week (seconds
into week)
ED Accuracy index
10
11
toe
Difference from GPS definition
Ephemeris epoch (seconds into week)
10
∆A
10

A
10
∆n0
10
∆ n0
Difference from semi major axis at toe
In the case of QZS, indicates
difference with 42,164,200 [m]
Change rate in semi major axis
Difference from mean motion
calculation at toe
Change rate from mean motion
calculation
10
M0-n
Mean anomaly at toe
10
en
Eccentricity
10
ωn
11
Ω0-n
11
I0-n
11
∆ Ω
11
io-n-DOT
11
Cis-n
11
Cic-n
11
Crs-n
11
Crc-n
11
Cus-n
11
Cuc-n
Argument of perigee
Longitude of ascending node at the
beginning of the week
Orbit inclination at toe
Rate of Right ascension of ascending
node (RAAN) difference from
reference value*1
Change rate in orbit inclination
Amplitude of the sine harmonic
correction term to the angle of
inclination
Amplitude of the cosine harmonic
correction term to the angle of
inclination
Amplitude of the sine harmonic
correction term to the orbit radius
Amplitude of the cosine harmonic
correction term to the orbit radius
Amplitude of the sine harmonic
correction term to the argument of
latitude
Amplitude of the cosine harmonic
correction term to the argument of
latitude
* Relative to
−9

Ω
REF = −2.6 × 10
In the case of GPS, indicates
difference with 26,559,710 [m]
For QZSS, no restrictions on
parameter range (for GPS : 0.0 ~
0.03)
[semi-circles/second] (same value with GPS)
125
IS-QZSS Ver. 1.6
(1) Transmission Week Number
Bits 39 ~ 51 in message type 10 constitute a binary expression for the 8192 remainder of the
current GPS Week Number. This is the same as Section 20.3.3.1.1.1 in Applicable Document
(2).
(2) Signal health (L1/L2/L5)
The three single bits from bit 52 to bit 54 in message type 10 indicate the health of the L1, L2
and L5 signals, respectively, transmitted by the corresponding satellite.
The value for the L1 signal is "1" in the event that there is a problem with one or more of the
L1C/A, L1-SAIF or L1C signals.
0
1
No problems with signal
Problem with signal exists or signal cannot be used
These bit indices are compared to the monitoring results at the present time for the
corresponding satellite. The details are in accordance with Section 5.1.2.1.3.
Health data are also present in message types 12, 31 and 37. The data in message type 10 are
uploaded at a different time, so the data may differ from that for the transmission satellites of
other messages and other satellite data.
(3) Data Predict Time of week: top
Bits 55-65 in message type 10 indicate the data predict time of week (top). The top term provides
the epoch time of week of the state estimate utilized for the prediction of satellite ephemeris
parameters. This is the same as in Section 20.3.3.1.1.3 of Applicable Document (2).
(4) Elevation Dependent Accuracy indicator: URAED index
Bits 66-70 in message type 10 indicate the Elevation Dependent (ED) Component of accuracy
indicator. For more information, see Section 5.1.2.1.3.2.
(5) Ephemeris data epoch: toe
Bits 71 ~ 81 in message type 10 and bits 39 ~ 49 in message type 11 indicate the epoch for
Ephemeris data. This is the same as Table 20-I in Applicable Document (2).
(6) Ephemeris data
After the URAED index in message type 10, the Ephemeris data (shown in Table 5.6.2-3) for the
corresponding satellite are transmitted. In the data, ΔA represents the value of the Semi-Major
Axis in the context of toe, A (toe), minus 42,164,200 [m]:
∆A (t oe ) = A (t oe ) − 42,164,200 [ m]
Other values are the same as Table 20-I in Applicable Document (2).
5.6.2.2.1.2 Characteristics of Ephemeris Data Parameters for Message Types 10 and 11
With the exception of those items shown in the previous section (Section 5.6.2.2.1.1), the
parameter characteristics for message types 10 and 11 (number of bits, LSB scale factor, data
range and units) are the same as Table 20-I in Applicable Document (2).
Bit allocation for message types 10 and 11 is the same as Figure 20-1 and 20-2 in Applicable
Document (2). However, Integrity Status Flag and L2C Phasing Flag were added in Figure 20-1
of Applicable Document (2), QZS-1 at current MCS did not adopt. (fixed at "0"(B))
5.6.2.2.1.3 Message Types 10 and 11: User Algorithms for Satellite Positioning
In accordance with Section 6.3.5.
126
IS-QZSS Ver. 1.6
5.6.2.2.2 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: SV Clock Correction
Parameters
5.6.2.2.2.1 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: Content of SV Clock
Parameters
Message types 30, 31, 32, 33, 34, 35, 37, 46, 47, 49, 51 and 53 all contain SV clock parameters
for the corresponding satellite such as those shown in Table 5.6.2-4. For an overview, see Section
20.3.3.2 in Applicable Document (2).
Table 5.6.2-4 Definition of SV clock parameters for Navigational Message D L5
Parameter
Definition
Difference from GPS definition
toc
SV clock parameter epoch (seconds into week)
URANED0 index
NED Accuracy index
URANED1 index
NED Accuracy change index
URANED2 index
NED Accuracy change rate index
af0-n
SV clock bias correction term
af1-n
SV clock drift correction term
af2-n
SV clock drift rate correction term
(1) Data predict time of accuracy indicator for SV clock parameters (top)
Bits 39 ~ 49 indicate the data predict time of week (top) for the accuracy indicator for the SV
clock parameters.
(2) Non-Elevation Dependent accuracy indicator (URANED index)
Bits 50 ~ 60 include the parameter needed to determine the Non-Elevation Dependent (NED)
User Range Accuracy (URANED). Details are in accordance with Section 5.1.2.1.3.2.
(3) SV clock parameter epoch (toc)
Bits 61 ~ 71 constitute the SV clock parameter epoch toc.
(4) SV clock parameter
The SV clock parameter for the corresponding satellite, shown in Table 5.6.2-4, will be
transmitted. The user algorithm is the same as Section 20.3.3.2.4 in Applicable Document (2).
However, certain parts of the definition are different; for more information, see Section 6.3.2.
5.6.2.2.2.2 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: Characteristics of SV
Clock Parameters
With the exception of those items shown in the previous section (Section 5.6.2.2.2.1), the
parameter characteristics for message types 30, 31, 32, 33, 34, 35, 37, 46, 47, 49, 51 and 53 (clock
correction parameter number of bits, LSB scale factor, data range and units) are the same as those
shown in Applicable Document (2) (Table 20-III).
127
IS-QZSS Ver. 1.6
5.6.2.2.2.3 Message types 30 through 35, 37, 46, 47, 49, 51 and 53: User Algorithm for SV
Clock Correction Data
(1) Calculation of Non-Elevation Dependent User Range Accuracy: URANED calculation.
The algorithm used to determine the detailed user positioning accuracy (Non-Elevation
Dependent (NED) component) (URANED) expressed by URANED index is the same as Section
20.3.3.2.4 in Applicable Document (2).
For more information about how to use URANED, see Section 3.1.2.1.3. For more information
about the content of URANED, see Section 5.1.2.1.3.
(2) Calculation of SV clock offset using SV clock parameters
As this is an estimate by the Control Segment by means of the L1C/A signal and the L2C signal
code measurement, there are additions to the SV clock correction algorithm for one-signal users
and 2-signal (L1C/A and L2C) users. See Section 6.3.2 for details.
(3) Data Predict Week Number
Bits 257-264 of Message Type 30 indicate the Data Predict Week Number (WNOP) to which the
Data Predict Time of Week (top) is referenced (see section 5.6.2.2.2.1(1)). The WNOP term
consists of eight bits which is a modulo 256 binary representation of the GPS week number to
which the top is referenced.
5.6.2.2.3 Message Type 30, 46: Ionospheric Parameter, Group Delay Differential Correction
Parameter and etc.
In addition to the SV clock parameters (Section 5.6.2.2.2), message type 30 includes the ionospheric
parameters like those shown in Table 5.6.2-5, the internal signal group delay correction parameters
shown in Table 5.6.2-6 and the ephemeris related parameter shown in table 5.5.2-7. For more
information regarding the content of these parameters, see Section 20.3.3.3 in Applicable Document
(2).
Ionospheric parameters in Message type 46 are rebroadcast of parameters broadcasted by GPS.
Since Group Delay Differential Correction parameters broadcasted by GPS is NOT rebroadcasted
by QZSS, bits 128 to 192 in message type 46 can NOT be used.
Table 5.6.2-5 Definition of ionospheric parameters for Navigational Message D L5
Parameter
Definition
Difference from GPS definition
α0
Ionospheric parameter α0 for Klobuchar model
Coefficient optimized for Japan & environs
α1
Ionospheric parameter α1 for Klobuchar model
Coefficient optimized for Japan & environs
α2
Ionospheric parameter α2 for Klobuchar model
Coefficient optimized for Japan & environs
α3
Ionospheric parameter α3 for Klobuchar model
Coefficient optimized for Japan & environs
β0
Ionospheric parameter β0 for Klobuchar model
Coefficient optimized for Japan & environs
β1
Ionospheric parameter β1 for Klobuchar model
Coefficient optimized for Japan & environs
β2
Ionospheric parameter β2 for Klobuchar model
Coefficient optimized for Japan & environs
β3
Ionospheric parameter β3 for Klobuchar model
Coefficient optimized for Japan & environs
128
IS-QZSS Ver. 1.6
Table 5.6.2-6 Group Delay Differential Correction Parameters (TGD, ISC) for Navigational
Message D L5
Parameter
Definition
Difference from GPS definition
TGD
Group Delay Differential Correction Term
between LCQZSS*1.and.L1C/A
Inter-Signal Correction Term for L1C/A (between
L1C/A and L1C/A) (Broadcasting value is 0.0)
Inter-Signal Correction Term for L2C (between
L1C/A and L2C)
Inter-Signal Correction Term for L5I5 (between
L1C/A and L5I5)
Inter-Signal Correction Term for L5Q5 (between
L1C/A and L5Q5)
LCGPS*2 and L1P(Y) for GPS
ISCL1C/A
ISCL2C
ISCL5I5
ISCI5Q5
L1P(Y) – L1C/A for GPS
L1P(Y) – L2C for GPS
L1P(Y) – L5I5 for GPS
L1P(Y) – L5Q5 for GPS
*1 LCQZSS: LCQZSS is the ionospheric error free linear combination of the L1C/A and L2C signals for QZSS
*2 LCGPS: LCGPS is the ionospheric error free linear combination of the L1P(Y) and L2P(Y) signals for GPS
Table 5.6.2-7 Ephemeris related parameter (WNop) for Navigational Message DL2C
Parameter
Definition
Difference from GPS definition
WNop
Data Predict Week Number at the data predict
time of week (top)
–
(1) Ionospheric parameters
This section provides the ionospheric parameters used by one-signal users (who use only the
L1, L2 or L5 signal) when they use an ionospheric model to calculate the ionospheric delay.
These parameters are specialized to fit the geographic area shown in Figure 4.1.5-1.
User algorithms for one-signal users are in accordance with Sections 6.3.4 and 6.3.8.
These parameters use data from the past 24 hours (Maximum) and are updated at least once per
day except "ionospheric maximum periods".
The number of bits, scale factor, ranges and units are the same as Table 20-IV in Applicable
Document (2).
(2) Estimating the L1-L5 group delay difference
Group delay differential correction terms TGD, ISCL5I5 and ISCL5Q5 for users of only one signal
(L5) and L1/L5 are contained in bits 128-140, 167-192 of message type 30. The numbers of
bits, scale factor, range and units are the same as Table 20-IV in Applicable Document (2).
However bit string for each parameter is "1000000000000", it indicates that the group delay
differential correction parameter cannot be used. The relevant algorithms are shown in Sections
6.3.3 and 6.3.4.
(3) Data Predict Week Number
Bits 257-264 of Message Type 30 indicate the Data Predict Week Number (WNOP) to which the
Data Predict Time of Week (top) is referenced (see section 5.6.2.2.2.1(1)). The WNOP term
consists of eight bits which is a modulo 256 binary representation of the GPS week number to
which the top is referenced.
129
IS-QZSS Ver. 1.6
5.6.2.2.4 Message Types 31, 12, 37, 47, 28 and 53: Almanac Data
QZS Almanac data are provided by message types 31, 12 and 37. The Reduced Almanac is provided
by message type 31 or 12, and the Midi Almanac is provided by message type 37. The PRN number
for these message types indicates the last 6 bits of the QZS PRN.
Almanac data for other satellite positioning systems are provided by message types 47, 28 and 53.
The Reduced Almanac is provided by message type 47 or 28, and the Midi Almanac is provided by
message type 53. Of the PRN numbers for these message types, numbers 1-32 are for GPS satellites.
However according to Applicable document (2), PRN No. for GPS satellites are extended to 1 ~ 63,
it would not be supported by QZS-1 at current MCS.
The Reduced Almanac for satellites is broadcast by a single satellite in a shorter interval than the
Midi Almanac.
Table 5.6.2-8 Definition of Midi Almanac parameters for Navigational Message DL5
Parameter
WNa-n
toa
PRN no.
L1/L2/L5
Health
E
δi

Ω
A
Definition
Difference from GPS definition
GPS Week Number at the time of Midi Almanac
generation
Midi Almanac epoch (second in week)
When the message type number is 37, it indicates
that this value is for a QZS satellite and represents
the last 6 bits of the QZS PRN.
When the message type number is53, it indicates
that this value is the PRN value for a GPS satellite
(PRN No. = 1 ~ 32).
L1, L2 and L5 signal health
Eccentricity (offset from the nominal QZS
eccentricity of 0.06)
Offset from the reference QZS orbit inclination
(0.25 [semi-circles]) (Offset from 0.25 [semicircles]= 45 [deg])
Change rate in right ascension of ascending node
(RAAN)
Square root of Semi-Major Axis
ω
Longitude of ascending node at the beginning of the
week
Argument of perigee
M0
Mean anomaly
af0
Bias term for SV clock
af1
Drift term for SV clock
Ω0
For GPS, PRN number is
extended to 1 ~ 63, but it is not
supported by QZS-1 at current
MCS.
130
In the case of GPS, "e" means
eccentricity value itself.
In the case of GPS, the reference
inclination is 0.3 [semi-circles],
which represents 54 [deg].
IS-QZSS Ver. 1.6
Table 5.6.2-9 Definition of Reduced Almanac parameters for Navigational Message DL5
Parameter
Definition
Difference from GPS definition
For GPS, PRN number is
extended to 1 ~ 63, but it is not
supported by QZS-1 at current
MCS.
Ω0
GPS Week Number at the time of Reduced Almanac
generation
Reduced Almanac epoch (second in week)
When the message type number is 31 or 12, it
indicates that this value is for a QZS satellite and
represents the last 6 bits of the QZS PRN.
When the message type number is 47 or 28, it
indicates that this value is the PRN value for a GPS
satellite (PRN No.= 1 ~ 32)
Offset from the nominal QZS Semi-Major Axis of
42,164,200 [m]
Longitude of ascending node at the beginning of the
week
Φ0
Argument of latitude (= M0 + w)
L1/L2/L5
Health
L1, L2 and L5 signal health
WNa-n
toa
PRN no.
δA
(e)
(δi)
(ω)
Implicit eccentricity (0.075 in the case of QZS)
(precondition for above parameter)
Fixed at –0.0111 [semi-circles], the offset from the
reference QZS orbit inclination of 0.25 [semi-circles]
(precondition for above parameter)
Implicit Argument of Perigee (270 [deg] in QZS1)(Precondition for above parameters)
131
In the case of GPS, indicates the
offset from 26,559,710 [m]
Based on the assumption that ω=
270 [deg]
0 in the case of GPS
In the case of GPS, fixed at
+0.0056 [semi-circles], the offset
from 0.3 [semi-circles]
0 [deg] in case of GPS
IS-QZSS Ver. 1.6
5.6.2.2.4.1 Almanac Reference Week Number
Bits 39 ~ 51 in message types 12 and 28 and bits 128 ~ 140 in message types 31 and 37 (and 47
and 53) indicate the Week Number (WNa-n) that serves as a reference for the Almanac reference
time (toa). WNa-n is made up of 13 bits and is expressed by the modulo-8192 GPS Week Number
(see Section 6.3.6) that serves as a reference for toa.
5.6.2.2.4.2 Almanac reference time
Bits 52 ~ 59 in message type 12 (and 28) and bits 141 ~ 148 in message types 31 and 37 (and also
47 and 53) indicate the Almanac reference time (toa).
5.6.2.2.4.3 Satellite PRN number
The first 6 bits in the 31-bit Reduced Almanac included in message types 31 and 12 (and also 47
and 28) constitute the corresponding satellite’s PRN. In the case of message types 31 and 12, the
PRN constitutes the last 6 bits of the QZS PRN. In the case of message types 47 and 28, the PRN
is a GPS PRN (PRN No. = 1 ~ 32).
There is a PRN in bits 149-154 of the Midi Almanac included in message type 37 (and 53). In the
case of message type 37, the PRN constitutes the last 6 bits of the QZS PRN. In the case of
message type 53, the PRN number 1 to 32 is a GPS PRN number.
If the Almanac data is not effective, the value of the PRN Number is set to "111111"(B) as in
Applicable Document (2). In this event, the remainder of the rest of 22 bits in the data block shall
be filler bits, i.e., alternating ones and zeros beginning with one, and the 3-Bit-Health is set to
"111"(B) (cf. Section 5.5.2.2.4.4). When the PRN number is 0 (PRN No. = "000000"(B)), it means
that the data packet includes dummy data for GPS. But in the case of QZSS at current MCS, it
means that the MCS could not acquire the data and the 22 bits in data packets are all "0"(B)s for
QZS-1.
5.6.2.2.4.4 Signal health (L1/L2/L5)
The three 1-Bit Health indicators – bits 155, 156 and 157 in message type 37 (and 53) and bits
29, 30 and 31 in the Reduced Almanac in message types 31 and 12 (and 28) relate to the L1, L2
and L5 signals for the satellite corresponding to the PRN number. Their meaning is covered in
Section 5.1.2.1.3.
5.6.2.2.4.5 Midi Almanac data content
Message type 37 (and 53) provides the Almanac for the satellite with the PRN number shown in
the message.
The number of bits, scale factor, ranges and units are the same as Table 20-V in Applicable
Document (2). However, the QZS eccentricity differs from that of GPS and is provided relative
to the reference values as noted below. For inclination, reference inclination value for QZSS is
differs from that of GPS as noted below.
(1) Eccentricity
(a) In the case of QZSS:
ea = 0.06 + e nav
(b) In the case of GPS: ea = 0.00 + e nav
Reference in accordance with Applicable Document (2)
:
Actual eccentricity value
ea
enav :
Eccentricity value included in navigation message
132
IS-QZSS Ver. 1.6
(2) Inclination
(a) In the case of QZSS: ia = 0.25 + δ i [semi-circle]
(b) In the case of GPS: ia = 0.3 + δ i [semi-circle]
Reference in accordance with Applicable Document (2)
Actual inclination value
ia:
:
Inclination value included in navigation message
i
δ
For the user algorithm, see Section 6.3.6.
The Midi Almanac for the QZS data is updated at least once every 6 days. The velocity calculated
by the Midi Almanac data is accurate within 30 [m/s].
5.6.2.2.4.6 Content of Reduced Almanac Data
Message type 31 and 12 (and also 47 and 28) contain multiple reduced Almanac data values.
Reduced Almanac data values are provided relative to reference values as shown below.
(1) Semi-Major Axis
(a) For QZSS: A = 42,164,200[m] + δA
(b) For GPS: A = 26,559,710[m] + δA
Reference in accordance with Applicable Document (2)
(2) Eccentricity
(a) For QZSS: e = 0.075
(b) For GPS: e = 0.0
Reference in accordance with Applicable Document (2)
(3) Orbit Angle of Elevation
(a) For QZSS: i = 43 [deg]
(b) For GPS: i = 55 [deg]
Reference in accordance with Applicable Document (2)
(4) Time change rate for right ascension of ascending node (RAAN)
 = －8.7 × 10 −10 [semi-circles/seconds]
(a) For QZSS: Ω
 = −2.6 × 10 −9 [semi-circles/seconds]
(b) For GPS: Ω
Reference in accordance with Applicable Document (2)
(5) Implicit Argument of Perigee
(a) For QZSS: ω = 270 [deg]
(b) For GPS:
ω = 0 [deg]
The number of bits, LSB scale factor, ranges and units are the same as Table 20-VI in Applicable
Document (2).
For the user algorithm, see Section 6.3.6.
The Reduced Almanac data for the QZS are updated at least once every 3 days. The velocity
calculated by the Reduced Almanac data is accurate within 350 [m/s].
5.6.2.2.5 Message type 32: Earth Orientation Parameter (EOP)
The Earth Orientation Parameter is included in message type 32. The definition, number of bits,
scale factor, range, units, LSB, user algorithm, etc., for this parameter are all the same as Section
20.3.3.5 in Applicable Document (2).
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5.6.2.2.6 Message type 33, 49: UTC Parameters
The UTC parameters are included in message type 33 (and 49). When the Message Type = 33, the
UTC parameters transmitted by the QZS is needed to link GPS time to UTC (NICT). When the
Message Type = 49, those are gathered by receiving GPS signals at QZS Monitor Stations and rebroadcasted to link GPS time to UTC (USNO). The number of bits, scale factor, range, units, LSB,
user algorithm, etc., for this parameter are almost the same as Section 20.3.3.6 in Applicable
Document (2). However, the bit length of WNLSF (Leap second reference Week Number) for QZS1, 13 bits.
5.6.2.2.7 Message Type 34, 13, 14: Differential Correction Data (DC Data)
Differential correction data (DC data) are included in message types 34, 13 and 14. These
parameters provide users with correction terms for SV clock parameters and Ephemeris data
transmitted by other satellites. DC data is divided into packets that comprise a 34-bit SV clock error
correction (CDC) parameter and a 92-bit Ephemeris error correction (EDC) parameter. CDC and
EDC data are paired, and users must use the CDC and EDC pair corresponding to the same top-D
and tOD.
Message type 34 includes the CDC and EDC for one satellite. Message type 13 includes the CDC
data for six satellites, while message type 14 includes the EDC data for two satellites.
A DC Type indicator "0" indicates that the corresponding correction parameters should be applied
to CNAV data, while "1" indicates that the corrections should be applied to the navigation message
for the L1C/A signal.
The content of the data packets is the same as Section 20.3.3.7 in Applicable Document (2). The
content is shown in Table 5.6.2-10.
The bit definition, number of bits, scale factor and unit for DC data are the same as Figure 20-17
and Table 20-X in Applicable Document (2).
If the DC data is not effective, the value of the PRN Number is set to "11111111"(B) as Section
20.3.3.7.2.3 in Applicable Document (2). In this case, DC type indicator is set to "0".
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Table 5.6.2-10 Definition of parameters for DC data for Navigational Message DL5
Parameter
Definition
Difference from GPS definition
top-D
tOD
DC Type indicator
Prediction time of week for DC data
(second in week)
Reference time of week for DC data
(second in week)
1: For DLIC/A message
δ af0
0: For DL2C message
PRN no. (range 0 ~ 255) for satellite for
which performance enhancement data will
be applied
1 ~ 32 if target is GPS; 193 ~ 197 if target
is QZSS
Bias term for SV clock
δ af1
Drift correction term for SV clock
UDRA index
User Differential Range Accuracy (UDRA)
PRN no.
For GPS, PRN number is
extended to 1 ~ 63, but it is not
supported by QZS-1 at current
MCS.
index
∆α
α correction term for Ephemeris parameter
∆β
β correction term for Ephemeris parameter
∆γ
γ correction term for Ephemeris parameter
∆i
Correction term for orbit inclination
Correction term for right ascension of
ascending node (RAAN)
Correction term for Semi-Major Axis
∆Ω
∆A
．
UDRA index
UDRA rate index
5.6.2.2.7.1 Differential Correction (DC) data
DC data include the following. For more information regarding the use of DC data, see Section
3.1.2.1.3.4.
(1) Time of DC data estimation (top-D)
"top-D" indicates the time (seconds into week) at which DC data were estimated. This value is
the same as Section 20.3.3.7.2.1 in Applicable Document (2).
(2) DC data epoch (tOD)
"tOD" indicates the epoch (seconds into week) for DC data. This value is the same as Section
20.3.3.7.2.2 in Applicable Document (2).
(3) Satellite PRN identification
The 8-bit PRN specifies the satellite for which the corresponding DC data set is to be used.
When PRN is 1-32, it indicates GPS; when PRN is 193-197, it indicates QZSS. According to
Applicable document (2), PRN No. for GPS satellites are extended to 1 ~ 63, but it would not
be supported by QZS-1 at current MCS.
If the bit values are all set to "1" (PRN No. = "11111111"(B)), then there are no DC data in the
data block. This is the same as Section 20.3.3.7.2.3 in Applicable Document (2) in the sense
that the remaining data consist of alternating bit values of "1"(B) and "0"(B).
(4) Use of CDC data
Same as Section 20.3.3.7 in Applicable Document (2). For more information, see Section
6.3.9.2.
(5) Use of EDC data
Same as Section 20.3.3.7 in Applicable Document (2). For more information, see Section
6.3.9.2.
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IS-QZSS Ver. 1.6
5.6.2.2.7.2 DC Data Accuracy
．
The User Differential Range Accuracy, UDRAop-D, and its time derivative, UDRA, indicate the
positioning accuracy after DC data have been applied to the SV clock parameter and Ephemeris
data.
The bit definition, number of bits, etc., and user algorithm are the same as Section 20.3.3.7.5 in
Applicable Document (2).
．
For more information regarding the use of UDRAop-D and UDRA, see Section 3.1.2.1.3.5.
5.6.2.2.8 Message type 35, 51: GPS/GNSS time offset: GGTO
Message type 35 (and 51) is the parameter used to adjust GPS time to match other GNSS (QZSS,
Galileo and GLONASS) times.
The bit definition, number of bits, scale factor (LSB), range and units are all the same as Table 02XI in Applicable Document (2).
In the case of Message Type ID= 51, the message is GPS retransmitting.
Table 5.6.2-11 Definition of GPS GNSS Time Offset (GGTO) parameters for Navigational
Message DL5
Parameter
Definition
tGGTO
Seconds into GGTO reference week
WNGGTO
GGTO reference Week Number
GNSS ID
See Section 5.6.2.2.8.1
A0GGTO
GPST bias term associated with other GNSS
system time
GPST drift term associated with other GNSS
system time
GPST drift rate term associated with other
GNSS system time
A1GGTO
A2GGTO
Difference from GPS definition
In the case of GPS, "011"(B)
means "spare".
5.6.2.2.8.1 GNSS - ID
Bits 157-159 in message type 35 define the other satellite positioning systems to which data
offsets with respect to GPS are applied. The definitions of these three bits are as follows.
000
001
010
011
100 ~ 111
Data cannot be used
Galileo
GLONASS
QZSS
Spare
5.6.2.2.8.2 GPS/GNSS Time Offset
The algorithm used to determine GPS GNSS Time Offset (GGTO) is the same as Section 20.3.3.8
in Applicable Document (2).
However, the QZS SV clock parameter already uses GPST as the reference, so the time offset
value for GPS and QZSS (GQTO) is always zero.
In the case of Message type ID = 18, it is rebroadcast of GPS message and the validity period of
the GGTO should be 1 day as a minimum (refer to section 30.3.3.8 in Applicable document (2)).
5.6.2.2.9 Message Types 15: Text Messages
Text messages are transmitted using the 29 8-bit ASCII characters in message type 15. The bit
definition, number of bits, etc., is the same as Section 20.3.3.9 in Applicable Document (2).
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IS-QZSS Ver. 1.6
5.7 LEX signal
5.7.1 RF Signal Characteristics
5.7.1.1 Signal Configuration
The LEX signal is modulated by BPSK (5), as specified in Section 5.1.
As shown in Figure 5.7.1-1, the LEX baseband signal, CLEX, is generated with a chipping rate of 5.115
[MChip/s] by interleaving the following two 2.5575 [Mcps] bit streams: (a) a 4 [ms] PRN Short Code
modulated by means of code shift keying (CSK) by the Reed-Solomon encoded Navigation message,
and (b) a 410 [ms] PRN Long Code modulated by squarewave with a period of 820 [ms] beginning
from 0 ("010101...").
As defined in Figure 5.7.1-1, CSK modulation shifts the phase of the PRN code by the number of
chips indicated by the 8-bit encoded Navigational message symbol.
1744 Bits/s
Nav Message
8bits/Symbol
Reed-Solomon(255,223)
Coding
250 Symbols/s (2000 Bits/s)
Short Code (4ms) : 2.5575MChip/s
2.5575MChip/s
CSK Modulator (*)
5.115 MChip/s
Ranging Code
Generator
C LEX
Long Code (410ms) : 2.5575MChip/s
Squarewave
which starts from “0”
ie. “010101…”
2.5575MChip/s
Clock 5.115MHz
820ms period
(*) Definition of Code shift Keying (CSK) Modulation
MSB
Nav Message Data
LSB
8 Bits (1Symbol) Value = N (as Decimal：N=0 - 255)
PRN(1)
PRN(10230)
Original PRN Code Pattern
PRN(N)
CSK Modulated PRN Code
Pattern by “N” value
Code Phase Shift by CSK Modulation
PRN(N+1)
PRN(102３０)
PRN(1)
PRN(N -1)
4 ms
Time
Figure 5.7.1-1 LEX Signal Structure
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IS-QZSS Ver. 1.6
5.7.1.2 Carrier Wave Properties
In accordance with Section 5.1.
5.7.1.3 Code Properties
5.7.1.3.1 Overview of LEX Code
As shown in Figure 5.7.1-2, the LEX signal code comprises a Kasami series Short Code (2.5575
[MChip/s]) with a chip length of 10,230 and a 4 [ms] period, and a Kasami series Long Code (2.5575
[MChip/s]) with a chip length of 1,048,575 and a 410 [ms] period.
G(X)=X20+X19+X16+X14+1
XOR
I
R 1
C
2.5575MHz
Short Code : 2.5575MChip/s
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
+
Initial Phase Register
G(X)=X10+X9+X6+X5+X4+X3+1
XOR
I
R 1
C
2
3
4
5
6
7
8
9 10
Initial Phase Register = All 1's
G(X)=X20+X19+X16+X14+1
XOR
I
R
Long Code : 2.5575MChip/s
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
+
C
Initial Phase Register
1048575 Count
10230 Count
OR
Counter
Week reset Command
Week reset port
Register Inputs
I - Input
R - Reset to initial conditions
C - Clock
Figure 5.7.1-2 Block diagram of LEX code generation
5.7.1.3.2 Code Generation
Separate 20-bit stage code generators are used to generate the two code patterns (Short Code and
Long Code). The satellite numbers (PRN numbers) are identified by the default settings for each of
these code generators.
Table 5.7.1-1 shows the default values corresponding to the QZS satellite numbers.
The initialization period for each code generator is 4 [ms] in the case of the Short Code generator
and 410 [ms] in the case of the Long Code generator. Both the Short Code generator and the Long
Code generator are initialized at the end/beginning of the week. Figure 5.7.1-3 shows the timing
relationship between the LEX Short Code and Long Code.
The PRN number is in accordance with Section 5.1.1.11.2.
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IS-QZSS Ver. 1.6
Table 5.7.1-1 LEX code phase assignment
Initial shift register state
QZS SV ID
PRN No.
Short (Octal)
Long (Octal)
1
193
0255021
0000304
2
194
0327455
0237663
3
195
0531421
0467237
4
196
0615350
0550370
5
197
0635477
1703243
The first digit in the octal notation represents first two chip (i.e. Most significant digit
"0" in the binary notation shall be ignored)
For example.: In the case of 3742246 in the octal notation, the first 20 chips are '11
111 100 010 010 100 110' in the binary notation
End/Start of Week
4 ms
End/Start of Week
1
1
1
1
Symbol Symbol Symbol Symbol
1
1
1
1
1
Symbol Symbol Symbol Symbol Symbol
1
1
Symbol Symbol
・・・・・・
1
1
1
1
Symbol Symbol Symbol Symbol
10230
Chips
10230
Chips
・・・・・・
10230
Chips
Nav Message
10230
Chips
10230
Chips
10230
Chips
10230
Chips
10230
Chips
10230
Chips
10230
Chips
10230
Chips
10230
Chips
10230
Chips
10230
Chips
10230
Chips
LEX Short Code
410 ms
1048575 Chips
1048575 Chips
997425 Chips
1048575 Chips
LEX Long Code
0
390 ms
820 ms
1
Squarewave
391 ns (=1/2.5575MHz)
Short
Short
Short
・・・・・・
LEX Short Code
Long
Long
Long
・・・・・・
LEX Long Code
195.5 ns (=1/5.115MHz)
S
L
S
L
S
L
・・・・・・
LEX Signal (Chip by Chip Multiplexed Sinal)
The first LEX Short Code starts synchronously with the end/start of week epoch
Figure 5.7.1-3 Timing Relationship between the LEX Short Code and Long Code
5.7.1.3.3 Non-Standard Code
In the event that a problem with the QZSS occurs, a non-standard code (NSC) is transmitted. This
is done to protect the user by ensuring that users do not use erroneous signals.
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IS-QZSS Ver. 1.6
5.7.2 LEX Messages
5.7.2.1 Message Structure
The LEX message signal structure is shown in Figure 5.7.2-1. Each message is made up of a total of
2,000 bits: a 49-bit header, a 1695-bit data section and a 256-bit Reed-Solomon code. Transmission
of each Navigation message takes one second.
DIRECTION OF DATA FLOW FROM SV
1 seconds
2000 Bits
1
50
1745
Header
(49 Bits)
Data Part
(1695 Bits)
Reed-Solomon Code
(256 Bits)
MSB
LSB
1
33
41
49
Preamble
PRN
Message Type ID
32 Bits
8 Bits
8 Bits
"Alert" Flag - 1 Bit
Figure 5.7.2-1 LEX Message Structure
5.7.2.1.1 Preamble
At the beginning of each message is the 32-bit preamble. The value of the preamble is
00011010110011111111110000011101.
5.7.2.1.2 PRN No.
Each message has an 8-bit PRN number immediately following the preamble. The PRN number is
the PRN number for the satellite transmitting that message. In the case of PRN No. = 1 ~ 32, the
satellite is GPS and if PRN No. = 193 ~ 197, then the satellite is QZSS.
However, according to Applicable document (1), (2) and (3), PRN No. for GPS satellites are
extended to 1 ~ 63, it would not be supported by QZS-1 at current MCS.
5.7.2.1.3 Message Type ID
Each message has an 8-bit message type ID immediately following the PRN number. The message
type ID signifies the information included in that frame. Table 5.7.2-1 shows the relationship
between the message type ID and the information.
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IS-QZSS Ver. 1.6
Table 5.7.2-1 Definition of message type
Content
Notes
Message type
0~9
10 ~ 19
10
Spare (System use)
Signal health (35 satellites)
Ephemeris & SV clock (3 satellites)
For JAXA experiment
PRN Numbers for the
target satellites are as
follows:
1 ~ 32 : GPS satellites
193 ~ 195 : QZS
11
Signal health (35 satellites)
Ephemeris & SV clock (2 satellites)
Ionospheric correction
12
Orbit & Clock correction
URA & SV code biases
MADOCA-LEX
13
Carrier Phase Bias Correction etc.
MADOCA-LEX (for PPPAR)
T.B.D for details.
14 ~ 19
Spare
20 ~ 155
For experiment
156 ~ 255
For application demonstration in private
sector
For experimental user
except JAXA and users of
application demonstration
in private sector
For experimental users of
application demonstration
in private sector by means
of
performance
enhancement signal
5.7.2.1.4 Alert Flag
Each message has a 1-bit alert flag immediately following the message type ID. The alert flag
indicates the signal power of the LEX signal for that satellite and the health status of the data.
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IS-QZSS Ver. 1.6
5.7.2.1.5 FEC Encoded Algorithm
Reed-Solomon (255, 223) encoding is applied the 1,744 bits of the Navigation message (preamble,
PRN, message type ID, alert flag and data section). Every 8 bits of the resulting bit-stream
comprises one symbol. (See Section 6.5.1 for details)
In order to add the 32-symbol (256-bit) Reed-Solomon code to the 218-symbol (1,744-bit)
Navigation message, nine "0" symbols (72 bits) are inserted at the beginning of the 214-symbol
(1,712-bit) data bit string that does not include the 4-symbol (32-bit) preamble at the beginning of
the header. The resulting 223-symbol (1,784-bit) data bit string (with the 9 zero symbols inserted)
is Reed-Solomon encoded (255,223) to generate a 32-symbol (256-bit) parity word. The 250
symbols (2,000 bits) that comprise the 32-symbol parity words added to the original 218-symbol
(1,744-bit) data bit string (including the preamble) are then input to the CSK Modulator (see Figure
5.7.2-2).
218 Symbols (1744 Bits)
214 Symbols (1712 Bits)
Header
Data Part
49 Bits
1695 Bits
Preamble
4 Symbols (32Bits)
Original Bit Strings
Insert Zero “0” Symbol – 9 Symbols (72 Bits )
223 Symbols (1784 Bits)
Zero “0”
9 Symbols
Data Part
1695 Bits
GF(28) RS(255,223) Encode
Delete Zero “0” Symbol – 9 Symbols (72 Bits )
250 Symbols (2000 Bits)
Broadcast
Header
Data Part
49 Bits
1695 Bits
Parity (RSC)
32 Symbols (256 Bits)
Preamble
4 Symbols (32Bits)
Figure 5.7.2-2 Reed-Solomon Encoding
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IS-QZSS Ver. 1.6
5.7.2.2 Message Content
5.7.2.2.1 Message types 10 and 11
Message types 10 and 11 are JAXA test messages.
The 1,695-bit data section of message type 10 includes the signal health and Ephemeris & SV clock
data as shown in Figure 5.7.2-3.
The 1,695-bit data section of message type 11 includes the signal health, Ephemeris & SV clock
and ionospheric delay correction data as shown in Figure 5.7.2-4.
DIRECTION OF DATA FLOW FROM SV
500 Bits
21
1
34
20
Bits
toe
16
Bits
50
225
Signal Health
Packet
175 Bits
Ephemeris & SV Clock
Packet 1
276 MSBs in 477Bits
WN - 13 Bits
TOW
DIRECTION OF DATA FLOW FROM SV
500 Bits
501
702
Ephemeris & SV Clock
Packet 1
201 LSBs in 477Bits
Ephemeris & SV Clock
Packet 2
299 MSBs in 477Bits
DIRECTION OF DATA FLOW FROM SV
500 Bits
1001
1179
Ephemeris & SV Clock
Packet 2
178 LSBs in 477Bits
Ephemeris & SV Clock
Packet 3
322 MSBs in 477Bits
DIRECTION OF DATA FLOW FROM SV
195 Bits
1501
1656
Ephemeris & SV Clock
Packet 3
155 LSBs in 477Bits
Reserved
40 Bits
Figure 5.7.2-3 Data Part, Message Type 10 – Signal Health, Ephemeris & SV Clock
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IS-QZSS Ver. 1.6
DIRECTION OF DATA FLOW FROM SV
500 Bits
21
1
34
50
20
Bits
toe
16
Bits
225
Signal Health
Packet
175 Bits
Ephemeris & SV Clock
Packet 1
276 MSBs in 477Bits
WN - 13 Bits
TOW
DIRECTION OF DATA FLOW FROM SV
500 Bits
501
702
Ephemeris & SV Clock
Packet 1
201 LSBs in 477Bits
Ephemeris & SV Clock
Packet 2
299 MSBs in 477Bits
DIRECTION OF DATA FLOW FROM SV
500 Bits
1001
1179
Ephemeris & SV Clock
Packet 2
178 LSBs in 477Bits
1391
Ionospheric Corection
Packet
212 Bits
Reserved
110 Bits
DIRECTION OF DATA FLOW FROM SV
195 Bits
1501
Reserved
195 Bits
Figure 5.7.2-4 Data Part, Message Type 11 – Signal Health, Ephemeris & SV Clock and
Ionospheric Correction
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IS-QZSS Ver. 1.6
5.7.2.2.1.1 Content of Message Types 10 and 11
(1) TOW Count
The 20-bit Time of Week (TOW) count at the beginning of the data section of message types
10 and 11 indicates the time (seconds into week) at the beginning of the next one-second
message.
The valid range is from 0 to 604799. The TOW included in the last message of the week is 0.
The TOW included in the first message of the week is 1.
(2) Transmission Week No. (WN)
The 13 bits from bit 21 to bit 33 in the data section of message types 10 and 11 constitute a
binary expression for the modulo-8192 GPS Week Number at the start of that message.
(3) Epoch for Ephemeris & SV clock parameters (toe)
The 16 bits from bit 34 through bit 49 in the data section of message types 10 and 11 constitute
the epoch for the Ephemeris & SV clock parameters stored in that message.
(4) Signal Health
Bits 50-224 in the data section of message types 10 and 11 constitute a signal health packet. As
shown in Figure 5.7.2-5, the signal health values for the three QZS satellites (PRN No. = 193
~ 195) and the 32 GPS satellites (PRN No. = 1 ~ 32) are broadcast in one batch.
The signal health for each QZS and GPS satellite is expressed in five bits (made up of five 1bit signal health flags) indicating the health of the L1, L2, L5, L1C and LEX signals in that
order.
When there is a problem with the signal for the corresponding satellite, the 1-bit signal health
flag for the L1, L2, L5 or L1C signal will be set to "1". In such cases, the pseudorange for that
signal for the corresponding satellite must not be used for range calculations.
The 1-bit signal health flag for the LEX signal changes to "1" when there is a problem with the
Ephemeris & SV clock parameters for that satellite that are being broadcast by the QZS. In such
cases, the LEX signal (from that satellite) must not be used for range calculations.
Signal Health Flag Value Definition
0
There is no problem with the signal
1
There is a problem with the signal and the data cannot be used
(5) Ephemeris & SV Clock Packet
Bits 225 ~ 701, bits 702 ~ 1178 and bits 1179 ~ 1655 in the data section of message type 10,
and bits 225 ~ 701 and bits 702 ~ 1178 in the data section of message type 11, each constitute
an Ephemeris & SV clock packet.
Each Ephemeris & SV clock packet includes a satellite ID for one satellite (SV ID), a User
Range Accuracy (URA) indicator, the Ephemeris, the SV clock and the group delay differential
correction parameter. For more information, see Section 5.7.2.2.1.2.
(6) Ionospheric Correction Parameter Packet
Bits 1179 ~ 1390 in the data section of message types 10 and 11 constitute an ionospheric
correction packet. For more information, see Section 5.7.2.2.1.3.
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IS-QZSS Ver. 1.6
DIRECTION OF DATA FLOW FROM SV
50 Bits
1
6
11
16
21
26
36
31
46
41
QZS 1
QZS 2
QZS 3
GPS 1
GPS 2
GPS 3
GPS 4
GPS 5
GPS 6
GPS 7
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
DIRECTION OF DATA FLOW FROM SV
50 Bits
51
56
61
66
71
76
91
86
81
96
GPS 8
GPS 9
GPS 10
GPS 11
GPS 12
GPS 13
GPS 14
GPS 15
GPS 16
GPS 17
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
DIRECTION OF DATA FLOW FROM SV
50 Bits
101
106
111
116
126
121
131
136
141
146
GPS 18
GPS 19
GPS 20
GPS 21
GPS 22
GPS 23
GPS 24
GPS 25
GPS 26
GPS 27
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
DIRECTION OF DATA FLOW FROM SV
25 Bits
151
156
161
166
171
GPS 28
GPS 29
GPS 30
GPS 31
GPS 32
5 Bits
5 Bits
5 Bits
5 Bits
5 Bits
Figure 5.7.2-5 Signal Health Packet Structure
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IS-QZSS Ver. 1.6
5.7.2.2.1.2 Content of Message Types 10 and 11 (Ephemeris & SV Clock Packet)
(1) Ephemeris & SV clock Packet
The Ephemeris & SV clock packet for each satellite is made up of 477 bits, as shown in Figure
5.7.2-6.
(2) Satellite ID: SV ID
The first 8 bits of each Ephemeris & SV clock packet constitute a satellite ID (SV ID). The SV
ID indicates the PRN number for the satellite corresponding to that data packet.
When the SV ID is set to all 1’s ("11111111"), it indicates that the packet does not contain
Ephemeris & SV clock data. In such cases, the remaining data bits of that packet will consist
of alternating "1"(B) and "0"(B) values starting with "1"(B).
(3) User Range Accuracy (URA) Indicator
Bits 9-12 of the Ephemeris & SV clock packet constitute an accuracy indicator for the
corresponding satellite. The URA index (N) is an integer from 0 to 15. This value has the
following relationship with the user range accuracy (URA) of the satellite.
URA index(N)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
URA (meters)
URA ≤ 0.08
0.08 < URA ≤ 0.11
0.11 < URA ≤ 0.15
0.15 < URA ≤ 0.21
0.21 < URA ≤ 0.30
0.30 < URA ≤ 0.43
0.43 < URA ≤ 0.60
0.60 < URA ≤ 0.85
0.85 < URA ≤ 1.20
1.20 < URA ≤ 1.70
1.70 < URA ≤ 2.40
2.40 < URA ≤ 3.40
3.40 < URA ≤ 4.85
4.85 < URA ≤ 6.85
6.85 < URA ≤ 9.65
9.65 < URA ( or no accuracy prediction available)
147
IS-QZSS Ver. 1.6
(4) Ephemeris
(a) Ephemeris parameter properties
The properties of the Ephemeris parameters for message types 10 and 11 (number of bits,
LSB scale factor and units) are in accordance with Table 5.7.2-2.
(b) User Algorithm for Determining Satellite Position
The satellite antenna phase center position in the ECEF system (x, y, z) should be calculated
using the following equations.
1
1
ACCx ⋅ (t − t oe ) 2 + JERKx ⋅ (t − t oe ) 3 [m]
2
6
1
1
y = POSy + VELy ⋅ (t − t oe ) + ACCy ⋅ (t − t oe ) 2 + JERKy ⋅ (t − t oe ) 3 [m]
2
6
1
1
z = POSz + VELz ⋅ (t − t oe ) + ACCz ⋅ (t − t oe ) 2 + JERKz ⋅ (t − t oe ) 3 [m]
2
6
x = POSx + VELx ⋅ (t − t oe ) +
t:
Satellite time. This is the same as the t value discussed in Section 6.3.2. For
cases when the satellite time value extends beyond the end of the week (and
the beginning of the following week), if t − toe is greater than 302,400
seconds, 604,800 seconds should be subtracted; if t-toe is less than –302,400
seconds, 604,800 seconds should be added.
148
IS-QZSS Ver. 1.6
DIRECTION OF DATA FLOW FROM SV
100 Bits
1
9
13
46
SV ID
4
8 Bits Bits
URA
79
POSx
POSy
POSz
33 Bits
33 Bits
22 MSBs
U
DIRECTION OF DATA FLOW FROM SV
100 Bits
101
112
140
168
196
POSz
VELx
VELy
VELz
11 LSBs
28 Bits
28 Bits
28 Bits
ACCx
5
MSBs
DIRECTION OF DATA FLOW FROM SV
100 Bits
201
220
244
268
288
ACCx
ACCy
ACCz
JERKx
JERKy
19 LSBs
24 Bits
24 Bits
20 Bits
13MSBs
DIRECTION OF DATA FLOW FROM SV
100 Bits
301
308
7
LSBs
328
354
374
387
JERKz
Af0
Af1
TGD
ISCL1C/A
20 Bits
26 Bits
20 Bits
13 Bits
13 Bits
ISCL2C - 1 MSB
JERKy
DIRECTION OF DATA FLOW FROM SV
77 Bits
401
413
426
439
452
465
ISCL2C
ISCL5I5
ISCL5Q5
ISCL1CP
ISCL1CD
ISCLEX
12 LSBs
13 Bits
13 Bits
13 Bits
13 Bits
13 Bits
Figure 5.7.2-6 Ephemeris & SV Clock Packet Content
149
400
IS-QZSS Ver. 1.6
Table 5.7.2-2 Definition of ephemeris parameters for Navigational Message DLEX navigation
message
Parameter
No. of Bits Scale Factor (LSB)
Units
WN
GPS Week Number
13
1
Weeks
toe
Ephemeris epoch (seconds into week)
PRN number (range 0 ~ 255) for
satellite for which ephemeris parameter
will be applied.
1-32 for GPS; 193-197 for QZSS
User range accuracy index
16
15
Seconds
8
–
–
–
–
SV ID
URA index
4
*
-6
m
POSx
X coordinate : Position coefficient
33
2
POSy
Y coordinate : Position coefficient
33*
2-6
m
POSz
Z coordinate : Position coefficient
*
33
2
-6
m
VELx
X coordinate : Velocity coefficient
28*
2-15
m/s
VELy
Y coordinate : Velocity coefficient
*
28
2
-15
m/s
VELz
Z coordinate : Velocity coefficient
28*
2-15
m/s
*
-24
m/s2
ACCx
X coordinate : Acceleration coefficient
24
2
ACCy
Y coordinate : Acceleration coefficient
24*
2-24
m/s2
ACCz
Z coordinate : Acceleration coefficient
24*
2-24
m/s2
JERKx
X coordinate : Jerk coefficient
20*
2-32
m/s3
JERKy
Y coordinate : Jerk coefficient
20*
2-32
m/s3
JERKz
Z coordinate : Jerk coefficient
20*
2-32
m/s3
* Parameters so indicated are in two’s complement notation.
(5) SV Clock Parameter
(a) Properties of SV Clock Parameter
The properties of the SV clock parameter in message types 10 and 11 (number of bits, LSB
scale factor and units) are in accordance with Table 5.7.2-3.
(b) User Algorithm for SV Clock Correction
With the exception of the relativistic effect, the time offset ∆tc (t) with respect to QZSST is
calculated using the following equation. The handling of other SV clock offsets is in
accordance with Section 6.3.2.
∆tc (t ) = A f0 + A f1 (t − toe )
t
[s]
Satellite time. This is the same as the t value discussed in Section 6.3.2. For
cases when the satellite time value extends beyond the end of the week (and
the beginning of the following week), if t-toe is greater than 302,400 seconds,
604,800 seconds should be subtracted; if t-toe is less than –302,400 seconds,
604,800 seconds should be added.
150
IS-QZSS Ver. 1.6
(6) Group Delay Differential Correction Parameter
(a) Properties of Group Delay Differential Correction Parameter
The properties of the group delay differential correction parameter in message types 10 and
11 (number of bits, LSB scale factor and units) are in accordance with Table 5.7.2-3.
If bit string of the Group Delay Differential Correction Parameters are set to
"1000000000000"(B), this indicates that the group delay differential correction parameter
cannot be used.
(b) Single-Signal User Algorithm for Group Delay Differential Correction Parameter
User receivers calculating range using measurements of only the LEX signal pseudorange
must use the following equation to correct the SV clock offset for the QZS. For more
information on correcting the SV clock offset for GPS, see Applicable Documents (1), (2)
and (3).
When ranging is conducted by combining different frequency signals from QZS and GPS
satellites, the receiver internal group delay difference must be properly corrected by the user
receiver.
(∆tsv )LEX = ∆tc − TGD + ISCLEX + ∆tr
∆ tc
∆ t r:
[s]
Time offset with respect to QZSST with the exception of the relativistic effect
Relativistic effect offset (as shown in Section 6.3.2)
(c) Dual-Signal User Algorithm for Group Delay Differential Correction Parameter
User receivers calculating range using measurements of the LEX signal pseudorange and the
pseudorange of another QZS or GPS signal, must use the following procedure for correction
of the ionospheric delay and SV clock offset. In addition, based on the definition of tsv shown
in Section 6.3.2, the transmitted values for ISCL1C/A are going to be as follows:
ISCL1C/A = 0
Correction of the GPS ionospheric delay and SV clock offset is in accordance with Applicable
Documents (1), (2) and (3).
When ranging is conducted by combining different frequency signals from QZS and GPS
satellites, the receiver internal group delay difference must be properly corrected by the user
receiver.
151
IS-QZSS Ver. 1.6
(i) Dual-Signal Users of L1C/A and LEX Signals
User receivers calculating range using measurements of the L1C/A and LEX signals should
use the following equation to correct the ionospheric delay.
PRLEX − L1C/A =
(PRLEX
− γ 1EX PRL1C/A ) + c(ISC LEX − γ 1EX ISC L1C/A )
− cTGD + c∆t sv
1 − γ 1EX
[m]
where
PRLEX-L1C/A:
PRL1C/A, PRLEX:
Pseudorange value corrected for the ionospheric delay and SV
clock offset
Pseudorange values observed using two signals
2
 154 
γ 1EX =   :
 125 
∆ tSV
Square of the ratio of the L1 to LEX signal frequencies
Time offset with respect to QZSST including relativistic effect
(= ∆ tc + ∆ tr)
Relativistic effect correction indicated in Section 6.3.2
Speed of light indicated in Section 6.1.1
∆ tr:
c:
(ii)
Dual-Signal Users of L2C and LEX Signals
User receivers calculating range using measurements of the L2C and LEX signals should use
the following equation to correct the ionospheric delay.
PRL2C − LEX =
(PRL2C − γ EX2 PRLEX ) + c(ISC L2C − γ EX2 ISC LEX ) − cT
1 − γ EX2
GD
+ c∆t sv [m]
where
PRL2C-LEX:
PRL2C, PRLEX:
Pseudorange value corrected for the ionospheric delay and SV
clock offset
Pseudorange values observed using two signals
2
 125 
γ EX2 =   :
 120 
∆ tSV
∆ tr:
c:
Square of the ratio of the L1 and L2C to LEX signal frequencies
Time offset with respect to QZSST including relativistic effect
(= ∆ tc + ∆ tr)
Relativistic effect correction indicated in Section 6.3.2
Speed of light indicated in Section 6.1.1
152
IS-QZSS Ver. 1.6
(iii)
Dual-Signal Users of L5 and LEX Signals
User receivers calculating range using measurements of the L5 and LEX signals should use
the following equation to correct the ionospheric delay.
PRL5 − LEX =
(PRL5 − γ EX5 PRLEX ) + c(ISC L5 − γ EX5 ISC LEX ) − cT
1 − γ EX5
GD
+ c∆t sv
[m]
where
PRL5-LEX:
Pseudorange value corrected for the ionospheric delay and SV
clock offset
Pseudorange values observed using two signals (L5 and LEX) (In
the case of the L5 signal, either the L5I signal or the L5Q signal)
PRL5, PRLEX:
2
 125  :

 115 
γ EX5 = 
Square of the ratio of the LEX to L5 signal frequencies
∆ tSV
∆ tr:
c:
Time offset with respect to QZSST including relativistic effect
Relativistic effect correction indicated in Section 6.3.2
Speed of light indicated in Section 6.1.1
(iv)
Dual-Signal Users of L1C and LEX Signals
User receivers calculating range using measurements of the L1C and LEX signals should use
the following equation to correct the ionospheric delay.
PRLEX − L1C =
(PRLEX
− γ 1EX PRL1C ) + c(ISC LEX − γ 1EX ISC L1C )
− cTGD + c∆t sv
1 − γ 1EX
[m]
where
PRLEX-L1C:
PRL1C, PRLEX:
Pseudorange value corrected for the ionospheric delay and SV
clock offset
Pseudorange values observed using two signals (L1C and
LEX) (In the case of the L1C signal, either the L1CP signal or
the L1CD signal)
2
 154 
γ 1EX =   :
 125 
Square of the ratio of the L1C to LEX signal frequencies
∆ tSV
∆ tr:
c:
Time offset with respect to QZSST including relativistic effect
Relativistic effect correction indicated in Section 6.3.2
Speed of light indicated in Section 6.1.1
153
IS-QZSS Ver. 1.6
Table 5.7.2-3 Definition of SV clock and group delay differential correction parameters for
Navigational Message DLEX navigation messages
Parameter
No. of Bits
Scale Factor (LSB)
Units
Af0
Af1
SV clock bias correction coefficient
26*
2–35
SV clock drift correction coefficient
*
–48
s
20
2
13*
2–35
s
*
13
2
–35
s
ISCL2C
13*
2–35
s
ISCL5I5
*
13
2
–35
s
ISCL5Q5
13*
2–35
s
ISCL1CP
*
13
2
–35
s
ISCL1CD
13*
2–35
s
*
–35
s
TGD
ISCL1C/A
(Zero "0" in the case of QZS)
ISCLEX
13
2
s/s
* Parameters so indicated are in two’s complement notation.
5.7.2.2.1.3 Content of Message Type 11 (ionospheric correction packet)
(1) Ionospheric Correction Parameter Packet
The ionospheric correction parameter packet is made up of 212 bits, as shown in Figure 5.7.27.
(2) Properties of Ionospheric Correction Parameter
The properties of the ionospheric correction parameter for message type 11 (number of bit, LSB
scale factor and units) are in accordance with Table 5.7.2-4.
When the ionospheric delay correction standard time is set to all 1’s ("11111111111111111111"),
it indicates that the packet does not contain an ionospheric delay correction parameter. In such
cases, the remaining data bits of that packet will consist of alternating "1" and "0" values
starting with 1.
The ionospheric delay correction parameter should only be used during the valid time (TSPAN)
starting from the time expressed by the ionospheric delay correction standard Week Number
(WNIONO) and the ionospheric delay correction standard time (tIONO). The ionospheric delay
correction parameter should be used only when the user receiver latitude and longitude are
within the domain indicated in Figure 4.1.5-1 of Section 4.1.5.
154
IS-QZSS Ver. 1.6
Table 5.7.2-4 Definition of ionospheric correction parameters for LEX navigation messages
Parameter
No. of Bits Scale Factor (LSB)
Units
Reference time of week for ionospheric
correction
Reference Week Number for ionospheric
WNIONO
correction
TSPAN
Valid time
Latitude coordinates of the origin of
φ0
approximate function
Longitude coordinates of the origin of
λ0
approximate function
Coefficient of approximate function
E00
0–0 degree (latitude–longitude)
Coefficient of approximate function
E10
1–0 degree (latitude–longitude)
Coefficient of approximate function
E20
2–0 degree (latitude–longitude)
Coefficient of approximate function
E01
0–1 degree (latitude–longitude)
Coefficient of approximate function
E11
1–1 degree (latitude–longitude)
Coefficient of approximate function
E21
2–1 degree (latitude–longitude)
* Parameters so indicated are in two’s complement notation.
tIONO
155
20
1
seconds
13
1
weeks
8
1
minute
19*
0.00001
radian
20*
0.00001
radian
22*
0.001
m
22*
0.01
m/radian
22*
0.01
m/radian2
22*
0.01
m/radian
22*
0.01
m/radian2
22*
0.1
m/radian3
IS-QZSS Ver. 1.6
DIRECTION OF DATA FLOW FROM SV
50 Bits
21
1
42
34
tIONO
WNIONO
TSPAN
φ0
20 Bits
13 Bits
8 Bits
9 MSBs
DIRECTION OF DATA FLOW FROM SV
50 Bits
51
61
81
φ0
λ0
E00
10 LSBs
20 Bits
20 MSBs
DIRECTION OF DATA FLOW FROM SV
50 Bits
101 103
125
147
E10
E20
E01
22 Bits
22 Bits
4 MSBs
E00 - 2 LSBs
DIRECTION OF DATA FLOW FROM SV
50 Bits
169
151
191
E01
E11
E21
18 LSBs
22 Bits
10 MSBs
DIRECTION OF DATA FLOW FROM SV
12 Bits
201
E21
12 LSBs
Figure 5.7.2-7 Ionospheric Correction Packet Content
156
IS-QZSS Ver. 1.6
(3) User Algorithm for Ionospheric Correction
User receivers calculating range using measurements of only one signal should correct the
ionospheric delay using the following ionospheric model.
Satellite transmission parameters
φ0, λ0: Latitude and longitude of the origin of approximate function in the coordinate
system defined in Section 3.1.4.2 [rad]
Approximate function coefficient
Enm:
Receiver generation parameters
Elevation angle between user receiver and satellite [rad]
El:
Az: Azimuth angle between user receiver and satellite [rad]
Latitude of user receiver in the coordinate system defined in Section 3.1.4.2 [rad]
φr:
Longitude of user receiver in the coordinate system defined in Section 3.1.4.2 [rad]
λr :
Constants
a:
Hiono:
γ Lx
Equatorial radius of the Earth in the coordinate system defined in Section 3.1.4.2
a = in accordance with Section 6.2.2.1.4 [m]
Height of ionospheric shell above the Earth
Hiono = 350,000 [m]
Square of ratio of Lx frequency (x = 2, 5, EX) to L1 frequency
2
2
 154 
 154 
 154 
 , γ L5 = 
 , γ LEX = 

 120 
 115 
 125 
2
γ L1 = 1, γ L 2 = 
Calculation parameters
(Tiono (t ) )Lx Diagonal ionospheric delay of frequency Lx (x = 1, 2, 5, EX)
F (t )
Inclination factor
φ pp (t )
Pierce point latitude in the coordinate system defined in Section 3.1.4.2
λ pp (t )
ψ pp (t )
Pierce point longitude in the coordinate system defined in Section 3.1.4.2
Angle formed by pierce point-earth's center-user receiver [rad]
Computational expressions
-
(Tiono (t ))Lx : Diagonal ionospheric delay of frequency X
(Tiono (t ))Lx = γ Lx F (t ) ∑ ∑ Enm (φ pp (t ) − φ0 ) n (λ pp (t ) − λ0 ) m
2
1
[m]
n=0 m=0
- F (t ) : Inclination factor
F (t ) = 1
-
 a cos El (t ) 

1 − 
 a + H iono 
2
[-]
φ pp (t ) : Pierce point latitude
φ pp (t ) = sin −1 {sin φr cosψ pp (t ) + cos φr sinψ pp (t )cos Az (t )}
[rad]
- λ pp (t ) : Pierce point longitude

sinψ pp (t )sin Az (t )
 cosψ pp (t ) cos φr − sinψ pp (t ) cos Az (t ) sin φr

ψ
(t
)
- pp : Angle formed by pierce point-earth's center-user receiver
λ pp (t ) = λr + tan −1 
ψ pp (t ) =


a
π
− El (t ) − sin −1 
⋅ cos El (t ) 
2
 a + H iono

157




[rad]
[rad]
IS-QZSS Ver. 1.6
5.7.2.2.1.4 Transmitting Intervals, Updating Intervals and Validity Period
(1) Transmitting Intervals
The sequence for transmitting message types 10 and 11 is arbitrary under the condition as
shown in Table 5.7.2-5.
(2) Updating Intervals
Table 5.7.2-5 shows the nominal updating intervals for the messages parameters included in
message types 10 and 11.
(3) Validity Period
Table 5.7.2-5 shows the nominal validity period for the messages included in message types
10 and 11.
Table 5.7.2-5 Message type 10,11: transmitting interval, update interval and validity period
Nominal transmitting Nominal
update Nominal validity
Message data
interval
interval
period
Signal health
1 second
1 seconds
–
Ephemeris
12 seconds
3 minutes
toe + 3 minutes
SV clock
12 seconds
3 minutes
toe + 3 minutes
Ionospheric correction
12 seconds
30 minutes
–
158
IS-QZSS Ver. 1.6
5.7.2.2.2 (Unused number)
159
IS-QZSS Ver. 1.6
5.7.2.2.3 Message Types 21 ∼ 155
Message types 21-155 are for general public user testing by entities. Test personnel may store 1,695
bits of arbitrarily created data in the data section of message types 21–155. However, when message
types 10, 11 (for JAXA testing), message type 20 (for GSI testing) or message type 156-255 (for
application demonstration in private sector) are being broadcast, message types 21-155 will not be
broadcast.
5.7.2.2.4 Message Types 156 ~ 255
Message types 156–255 are for application demonstration in private sector. The contents of data are
described in Applicable document (6).
Satellite Positioning Research and Application Center manages usage of message types 156-255
5.7.2.2.5 Message Types 12
Message types 12 is JAXA test message which called "MADOCA-LEX".
The data section of message type 12 includes correction information of orbit & clock, URA and SV
code biases for the four multiple constellations (GPS, GLONASS, Galileo and QZSS) calculated
by "MADOCA" (=Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis).
These correction parameters are basically defined in Applicable document (7). The relation between
MADOCA-LEX messages and RTCM messages is shown in Figure 5.7.2-8.
However, when message type 12 is broadcasted, other JAXA test messages (type 10 and 11) will
not transmitted, simultaneously with Message Type 12.
LEX message(2000 bits/sec)
Data Part(1695 bits)
1
LEX
Header
(49bits)
21
TOW
(20bits)
1695
34
WN
(13bits)
SSR message part
SSR Packet
#1
(Variable)
Preamble
(8bits)
Reserved
(6bits)
Reserved
(Variable)
Message
Length
(10bits)
SSR Packet
#2
(Variable)
Variable Length
Data Message
(Variable)
SSR Packet
#N
(Variable)
・・・
Reserved
(Variable)
ReedSolomon code
(256bits)
ReedSolomon code
(256bits)
CRC
(24bits)
RTCM Message #1
Preamble
(8bits)
Reserved
(6bits)
Message
Length
(10bits)
Variable Length
Data Message
(Variable)
CRC
(24bits)
RTCM Message #2
・・・
RTCM v.3 Message structure
Preamble
(8bits)
Reserved
(6bits)
Message
Length
(10bits)
Variable Length
Data Message
(Variable)
CRC
(24bits)
RTCM Message #N
Figure 5.7.2-8 LEX message structure of Message Type 12
5.7.2.2.5.1 Content of Message Type 12
(1) TOW count
The 20-bit Time of Week (TOW) count at the beginning of the data section of message type 12
indicates the time (seconds into week) at the beginning of the next one-second message.
The valid range is from 0 to 604799. The TOW included in the last message of the week is "0".
The TOW included in the first message of the week is "1".
This specification is same with other JAXA test message (Type 10 and 11) (see Section
5.7.2.2.1.1(1)).
160
IS-QZSS Ver. 1.6
(2) Transmission Week No. (WN)
The 13 bits from bit 21 to bit 33 in the data section of message type 12 constitute a binary
expression for the modulo-8192 GPS Week Number at the start of that message.
This specification is same with other JAXA test message (Type 10 and 11) (see Section
5.7.2.2.1.1(2)).
(3) SSR message part
The rest bits in data section of message type 12 (from bit 34 to 1695) stores as SSR Packet
information equivalent of "Variable Length Data Message" in Version3 Frame Structure defined
by RTCM10403.2 (Applicable Document (7)).
SSR Packet consists of Header and Specific part. The contents of data format and definition is
same with applicable document (7).
The 12 bits in the top of Header part indicates RTCM message type number broadcasted by
LEX message. Table 5.7.2-6 shows the message type number summary of LEX message type
12. When the all bit of the message type number in each SSR Packet is "0", it indicates that
there are no the SSR packet in LEX message.
You can see the message type number list of SSR packet transmitted by MADOCA-LEX
(message type 12) on Table 5.7.2-6. The broadcast sequence of Message type number are
subject to change depending on the location of GNSS satellite constellation. Therefore, the user
of this LEX message should not expect a set pattern.
User algorithms for SSR message are in accordance with Section 6.5.2.1.
Table 5.7.2-6 Message type number list of SSR Packet transmitted by MADOCA-LEX Message
Message
Type
No.
Message Name
No. of bits
Remarks
Number
1
1057
SSR GPS Orbit Correction
68 + 135 × NS*2
2
1059
SSR GPS Code Bias
67 + 11×NS*2 + 19×ΣNCB*3
3
1061
SSR GPS URA
67 + 12×NS*2
4
1062
SSR GPS High Rate Clock Correction
67 + 28×NS*2
5
1063
SSR GLONASS Orbit Correction
65 + 134×NS*2
6
1065
SSR GLONASS Code Bias
64 + 10×NS*2 + 19×ΣNCB*3
7
1067
64 + 11×NS*2
8
1068
9
1240*1
SSR GLONASS URA
SSR GLONASS High Rate Clock
Correction
SSR GALILEO Orbit Correction
68 + 135×NS*2
10
1242*1
SSR GALILEO Code Bias
67 + 11×NS*2 + 19×ΣNCB*3
11
1244*1
67 + 12×NS*2
12
1245*1
13
1246*1
SSR GALILEO URA
SSR GALILEO High Rate Clock
Correction
SSR QZSS Orbit Correction
14
1248*1
SSR QZSS Code Bias
65 + 9×NS*2 + 19×ΣNCB※3
15
1250*1
SSR QZSS URA
65 + 10×NS*2
16
1251*1
SSR QZSS High Rate Clock Correction
65 + 26×NS*2
64 + 27×NS*2
67 + 28×NS*2
66 + 133×NS*2
*1 Message Type Numbers from 1240 to 1251: Defined in RTCM draft version.
*2 NS: Numbers of Satellites
*3 NCB: Numbers of Code Biases per individual Satellite
161
IS-QZSS Ver. 1.6
5.7.2.2.5.2 SSR Orbit Correction Messages
The contents of SSR Orbit Correction Messages for GPS, GLONASS, QZSS and Galileo is
shown below.
Content and format of some of the items follows RTCM standards version 10403.2 (Applicable
Document (7)). A notation that starts with "DF" in the column "Remarks" indicates the
corresponding Data Field in the documentation of RTCM version 10403.2 (Applicable Document
(7)).
162
IS-QZSS Ver. 1.6
(1) GPS (Message Type Number: 1057)
The contents of SSR GPS Orbit Correction Messages are shown in Table 5.7.2-7.
7
Table 5.7.2-7 SSR GPS Orbit Correction Messages (Message Type Number: 1057)
Data
No. of
Possible range Contents
Name
Remarks
Type
Bits
0 ~ 4095
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
GPS reference time (Full seconds
GPS Epoch Time
uint 20
20
0 ~ 604799[s] since the beginning of the GPS DF385
1s
week)
0 ~ 15
SSR
Update
The SSR Update Intervals for this
(Value:5
bit (4)
4
DF391
Interval
message.
(=30[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Orbit corrections refer to Satellite
Satellite Reference
Reference Datum: (0:ITRF, DF375
bit (1)
1
0 or 1
Datum
1:Regional)
Issue Of Data number for SSR in
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
8
SSR Solution ID
uint 4
4
0 ~ 15
9
No. of Satellites
uint 6
6
0 ~ 63
#
1
2
3
4
5
6
Subtotal (#1 ~ #9)
SSR Solution ID number
Number of Satellites included in
the message
DF415
DF387
68
#10 – #17 are repeated for each satellites (1 ~ NS (No. of Satellites))
10
GPS Satellite ID
uint 6
6
1 ~ 32
11
GPS IODE
uint 8
8
–
12
Delta Radial
int 22
22
±209.7151
[m]
Radial orbit correction
broadcast ephemeris.
13
Delta Along Track
int 20
20
±209.7148
[m]
Along-Track orbit correction for
broadcast ephemeris.
14
Delta Cross-Track
int 20
20
±209.7148
[m]
Cross-Track orbit correction for
broadcast ephemeris.
15
Dot Delta Radial
int 21
21
±1.048575
[m/s]
Velocity of Radial orbit correction
for broadcast ephemeris.
16
Dot Delta AlongTrack
int 19
19
±1.048572
[m/s]
17
Dot Delta CrossTrack
int 19
19
±1.048572
[m/s]
Subtotal (#10-#17)
Total
135
68 + 135 × NS
163
GPS Satellite ID
IODE
value of broadcast
ephemeris used for calculation of
Correction Differences.
for
Velocity of Along-Track orbit
correction
for
broadcast
ephemeris.
Velocity of Cross-Track orbit
correction
for
broadcast
ephemeris.
DF068
DF071
Resolution:
0.1[mm]
DF365
Resolution:
0.4[mm]
DF366
Resolution:
0.4[mm]
DF367
Resolution:
0.001[mm/s]
DF368
Resolution:
0.004[mm/s]
DF369
Resolution:
0.004[mm/s]
DF370
IS-QZSS Ver. 1.6
(2) QZSS (Message Type Number: 1246)
The contents of SSR QZSS Orbit Correction Messages are shown in Table 5.7.2-8.
7
Table 5.7.2-8 SSR QZSS Orbit Correction Messages (Message Type Number: 1246)
Data No. of
Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
QZSS Reference time (Full
QZSS Epoch Time
uint 20
20
0 ~ 604799[s] seconds since the beginning of *
1s
the GPS week)
0 ~ 15
SSR
Update
The SSR Update Intervals for
bit (4)
4
DF391
(Value:5
Interval
this message.
(=30[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Orbit corrections refer to
Satellite Reference
Satellite Reference Datum: DF375
bit (1)
1
0 or 1
Datum
(0:ITRF, 1:Regional)
Issue Of Data number for SSR in
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
8
SSR Solution ID
uint 4
4
0 ~ 15
9
No. of Satellites
uint 4
4
0 ~ 10
#
1
2
3
4
5
6
Subtotal (#1 ~ #9)
SSR Solution ID number
Number of Satellites included in
the message
*
66
#10 - #17 are repeated for each satellites (1 ~ NS (No. of Satellites))
QZSS Satellite ID (See Table
10 QZSS Satellite ID
uint 4
4
1 ~ 10
5.7.2-9)
IODE value of broadcast
11 QZSS IODE
uint 8
8
ephemeris used for calculation of
Correction Differences.
12
Delta Radial
int 22
22
±209.7151
[m]
Radial orbit correction
broadcast ephemeris.
13
Delta Along Track
int 20
20
±209.7148
[m]
Along-Track orbit correction for
broadcast ephemeris.
14
Delta Cross-Track
int 20
20
±209.7148
[m]
Cross-Track orbit correction for
broadcast ephemeris.
15
Dot Delta Radial
int 21
21
±1.048575
16
Dot Delta AlongTrack
int 19
19
±1.048572
[m/s]
17
Dot Delta CrossTrack
int 19
19
±1.048572
[m/s]
Velocity of Radial orbit
correction
for
broadcast
ephemeris.
Velocity of Along-Track orbit
correction
for
broadcast
ephemeris.
Velocity of Cross-Track orbit
correction
for
broadcast
ephemeris.
Subtotal (#10-#17)
Total
DF415
[m/s]
133
66 + 133 × NS
* Defined in draft version of RTCM.
164
for
*
*
Resolution:
0.1[mm]
DF365
Resolution:
0.4[mm]
DF366
Resolution:
0.4[mm]
DF367
Resolution:
0.001[mm/s]
DF368
Resolution:
0.004[mm/s]
DF369
Resolution:
0.004[mm/s]
DF370
IS-QZSS Ver. 1.6
Table 5.7.2-9 QZSS Satellite ID
ID
QZSS Satellite PRN
1
193
2
194
3
195
4
196
5
197
6
198
7
199
8
200
9
201
10
202
165
IS-QZSS Ver. 1.6
(3) Galileo (Message Type Number: 1240)
The contents of SSR Galileo Orbit Correction Messages are shown in Table 5.7.2-10.
7
Table 5.7.2-10 SSR Galileo Orbit Correction Messages (Message Type Number: 1240)
Data No. of
Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
GALILEO Reference time (Full
GALILEO Epoch
uint 20
20
0 ~ 604799[s] seconds since the beginning of *
Time 1s
the GALILEO week)
0 ~ 15
SSR
Update
The SSR Update Intervals for
(Value:5
bit (4)
4
DF391
Interval
this message.
(=30[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Orbit corrections refer to
Satellite Reference
Satellite Reference Datum: DF375
bit (1)
1
0 or 1
Datum
(0:ITRF, 1:Regional)
Issue Of Data number for SSR in
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
8
SSR Solution ID
uint 4
4
0 ~ 15
9
No. of Satellites
uint 6
6
0 ~ 63
#
1
2
3
4
5
6
Subtotal (#1 ~ #9)
SSR Solution ID number
Number of Satellites included in
the message
DF387
68
#10 - #17 are repeated for each satellites (1 ~ NS (No. of Satellites))
GALILEO
10
uint 6
6
0 ~ 63
GALILEO Satellite ID
Satellite ID
IODE value of broadcast
ephemeris used for calculation of
11
GALILEO IODE
uint 8
8
Correction Differences.
12
Delta Radial
int 22
22
±209.7151
[m]
Radial orbit correction
broadcast ephemeris.
13
Delta Along Track
int 20
20
±209.7148
[m]
Along-Track orbit correction for
broadcast ephemeris.
14
Delta Cross-Track
int 20
20
±209.7148
[m]
Cross-Track orbit correction for
broadcast ephemeris.
15
Dot Delta Radial
int 21
21
±1.048575
[m/s]
16
Dot Delta AlongTrack
int 19
19
±1.048572
[m/s]
17
Dot Delta CrossTrack
int 19
19
±1.048572
[m/s]
Subtotal (#10-#17)
Total
DF415
133
66 + 133 × NS
* Defined draft version of RTCM.
166
for
Velocity of Radial orbit
correction
for
broadcast
ephemeris.
Velocity of Along-Track orbit
correction
for
broadcast
ephemeris.
Velocity of Cross-Track orbit
correction
for
broadcast
ephemeris.
*
*
Resolution:
0.1[mm]
DF365
Resolution:
0.4[mm]
DF366
Resolution:
0.4[mm]
DF367
Resolution:
0.001[mm/s]
DF368
Resolution:
0.004[mm/s]
DF369
Resolution:
0.004[mm/s]
DF370
IS-QZSS Ver. 1.6
(4) GLONASS (Message Type Number: 1063)
The contents of SSR GLONASS Orbit Correction Messages are shown in Table 5.7.2-11.
Table 5.7.2-11 SSR GLONASS Orbit Correction Messages (Message Type Number: 1057)
Data No. of
# Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
1
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
GLONASS reference time (Full
GLONASS Epoch
2
uint 17
17
0 ~ 86400 [s] seconds since the beginning of DF386
Time 1s
the GLONASS day)
0~1
SSR
Update
The SSR Update Intervals for
3
bit (4)
4
(Value:5
DF391
Interval
this message.
(=30[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
4
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Orbit corrections refer to
Satellite Reference
Satellite Reference Datum: DF375
5
bit (1)
1
0 or 1
Datum
(0:ITRF, 1:Regional)
Issue Of Data number for SSR in
6
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
7
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
8
SSR Solution ID
uint 4
4
0 ~ 15
9
No. of Satellites
uint 6
6
0 ~ 63
Subtotal (#1 ~ #9)
SSR Solution ID number
Number of Satellites included in
the message
12
Delta Radial
int 22
22
±209.7151
[m]
Radial orbit correction
broadcast ephemeris.
13
Delta Along Track
int 20
20
±209.7148
[m]
Along-Track orbit correction for
broadcast ephemeris.
14
Delta Cross-Track
int 20
20
±209.7148
[m]
Cross-Track orbit correction for
broadcast ephemeris.
15
Dot Delta Radial
int 21
21
±1.048575
[m/s]
16
Dot Delta AlongTrack
int 19
19
±1.048572
[m/s]
17
Dot Delta CrossTrack
int 19
19
±1.048572
[m/s]
Total
DF387
65
#10 - #17 are repeated for each satellites (1 ~ NS (No. of Satellites))
GLONASS
10
uint 5
5
1 ~ 24
GPS Satellite ID
Satellite ID
IODE value of broadcast
11 GLONSS IOD
uint 8
8
0 ~ 255
ephemeris used for calculation of
Correction Differences.
Subtotal (#10-#17)
DF415
134
65 + 134 × NS
167
for
Velocity of Radial orbit
correction
for
broadcast
ephemeris.
Velocity of Along-Track orbit
correction
for
broadcast
ephemeris.
Velocity of Cross-Track orbit
correction
for
broadcast
ephemeris.
DF068
DF392
Resolution:
0.1[mm]
DF365
Resolution:
0.4[mm]
DF366
Resolution:
0.4[mm]
DF367
Resolution:
0.001[mm/s]
DF368
Resolution:
0.004[mm/s]
DF369
Resolution:
0.004[mm/s]
DF370
IS-QZSS Ver. 1.6
5.7.2.2.5.3 SSR Code Bias Messages
The contents of SSR Code Bias Correction Messages for GPS, GLONASS, QZSS and Galileo is
shown below.
Content and format of some of the items follows RTCM standards version 10403.2 (Applicable
Document (7)). A notation that starts with "DF" in the column "Remarks" indicates the
corresponding Data Field in the documentation of RTCM version 10403.2 (Applicable Document
(7)).
(1) GPS (Message Type Number: 1059)
The contents of SSR GPS Code Bias Correction Messages are shown in Table 5.7.2-12.
6
Table 5.7.2-12 SSR GPS Code Bias Correction Messages (Message Type Number: 1059)
Data No. of
Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
GPS reference time (Full
GPS Epoch Time
uint 20
20
0 ~ 604799[s] seconds since the beginning of DF385
1s
the GPS week)
0 ~ 15
SSR
Update
The SSR Update Intervals for
bit (4)
4
(Value:15
DF391
Interval
this message.
(=3[h]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Issue Of Data number for SSR in
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 6
6
0 ~ 63
#
1
2
3
4
5
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
DF415
DF387
67
#9 - #12 are repeated for each satellites (1 ~ NS (No. of Satellites: see #8))
9
10
11
12
GPS Satellite ID
No. of Code Biases
Processed
Subtotal (#9 + #10)
uint 6
6
1 ~ 32
uint 5
5
–
GPS Satellite ID
Number of Code Biases for one
individual satellite
Subtotal(#11+#12)
Total
DF379
11
#11 and #12 are repeated for NCB (No. of Code Biases Processed: see #10) times
GPS Signal and
No. of Code Bias Indicator to
Tracking
Mode uint 5
5
0 ~ 31
specify the GPS signal and
Indicator
tracking mode
Code Bias
DF068
Int 14
14
±81.91 [m]
19
67 + 11 × NS + 19 × ∑NCB
168
Code Bias for specified Signal
DF380
Resolution:
0.01[m]
DF383
IS-QZSS Ver. 1.6
(2) QZSS (Message Type Number: 1248)
The contents of SSR QZSS Code Bias Correction Messages are shown in Table 5.7.2-12.
#
1
2
3
4
5
6
Table 5.7.2-13 SSR QZSS Code Bias Correction Messages (Message Type Number: 1248)
Data No. of
Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
QZSS Reference time (Full
QZSS Epoch Time
uint 20
20
0 ~ 604799[s] seconds since the beginning of *
1s
the GPS week)
0 ~ 15
SSR
Update
The SSR Update Intervals for
(Value:15
bit (4)
4
DF391
Interval
this message.
(=3[h]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Issue Of Data number for SSR in
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 4
4
0 ~ 10
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
Subtotal (#9 + #10)
12
Int 14
Subtotal(#11+#12)
Total
*
DF379
11
#11 and #12 are repeated for NCB (No. of Code Biases Processed: see #10) times
No. of Code Bias Indicator to
QZSS Signal and
specify the QZSS signal and
Tracking
Mode uint 5
5
0 ~ 31
tracking mode (See Table
Indicator
5.7.2-14)
Code Bias
*
67
#9 ~ #12 are repeated for each satellites (1 ~ NS (No. of Satellites: see #8))
QZSS Satellite ID (See Table
9
QZSS Satellite ID
uint 4
4
1 ~ 10
5.7.2-9)
No. of Code Biases
Number of Code Biases for one
10
uint 5
5
–
individual satellite
Processed
11
DF415
14
±81.91 [m]
19
67 + 11 × NS + 19 × ∑NCB
* Defined in draft version of RTCM.
169
Code Bias for specified Signal
*
Resolution:
0.01[m]
DF383
IS-QZSS Ver. 1.6
Table 5.7.2-14 Indicator to specify the QZSS signal and tracking
ID
QZSS Signal and Tracking
0
L1 C/A
1
L1 L1C (D)
2
L1 L1C (P)
3
L2 L2C (M)
4
L2 L2C (L)
5
L2 L2C (M+L)
6
L5 I
7
L5 Q
8
L5 I+Q
9~
Reserved
170
IS-QZSS Ver. 1.6
(3) Galileo (Message Type Number: 1242)
The contents of SSR Galileo Code Bias Correction Messages are shown in Table 5.7.2-12.
#
1
2
3
4
5
6
Table 5.7.2-15 SSR Galileo Code Bias Correction Messages (Message Type Number: 1059)
Data No. of
Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
GALILEO Reference time (Full
GALILEO Epoch
uint 20
20
0 ~ 604799[s] seconds since the beginning of *
Time 1s
the GALILEO week)
0 ~ 15
SSR
Update
The SSR Update Intervals for
(Value:15
bit (4)
4
DF391
Interval
this message.
(=3[h]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Issue Of Data number for SSR in
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 6
6
0 ~ 63
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
Subtotal (#9 + #10)
12
Int 14
Subtotal(#11+#12)
Total
*
DF379
11
#11 and #12 are repeated for NCB (No. of Code Biases Processed: see #10) times
Galileo Signal and
No. of Code Bias Indicator to
Tracking
Mode uint 5
5
0 ~ 31
specify the Galileo signal and
Indicator
tracking mode
Code Bias
DF387
67
#9 ~ #12 are repeated for each satellites (1 ~ NS (No. of Satellites: see #8))
GALILEO
9
uint 6
6
0 ~ 63
GALILEO Satellite ID
Satellite ID
No. of Code Biases
Number of Code Biases for one
10
uint 5
5
–
individual satellite
Processed
11
DF415
14
±81.91 [m]
19
67 + 11 × NS + 19 × ∑NCB
* Defined in draft version of RTCM.
171
Code Bias for specified Signal
*
Resolution:
0.01[m]
DF383
IS-QZSS Ver. 1.6
(4) GLONASS (Message Type Number: 1065)
The contents of SSR GLONASS Code Bias Correction Messages are shown in Table 5.7.2-12.
Table 5.7.2-16 SSR GLONASS Code Bias Correction Messages (Message Type Number: 1059)
Data No. of
# Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
1
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
GLONASS reference time (Full
GLONASS Epoch
2
uint 17
17
0 ~ 86400 [s] seconds since the beginning of DF386
Time 1s
the GLONASS day)
0 ~ 15
SSR
Update
The SSR Update Intervals for
(Value:15
3
bit (4)
4
DF391
Interval
this message.
(=3[h]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
4
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Issue Of Data number for SSR in
5
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
6
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 6
6
0 ~ 63
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
Subtotal (#9 + #10)
12
Subtotal(#11+#12)
Total
DF068
DF379
11
#11 and #12 are repeated for NCB (No. of Code Biases Processed: see #10) times
GLONASS Signal
No. of Code Bias Indicator to
and
Tracking uint 5
5
0 ~ 31
specify the GPS signal and
Mode Indicator
tracking mode
Code Bias
DF387
67
#9 ~ #12 are repeated for each satellites (1 ~ NS (No. of Satellites: see #8))
GLONASS
9
uint 5
5
1 ~ 24
GPS Satellite ID
Satellite ID
No. of Code Biases
Number of Code Biases for one
10
uint 5
5
individual satellite
Processed
11
DF415
Int 14
14
±81.91 [m]
19
67 + 11 × NS + 19 × ∑NCB
172
Code Bias for specified Signal
DF380
Resolution:
0.01[m]
DF383
IS-QZSS Ver. 1.6
5.7.2.2.5.4 SSR URA quality Messages
The contents of SSR URA quality information Messages for GPS, GLONASS, QZSS and Galileo
is shown below.
Content and format of some of the items follows RTCM standards version 10403.2 (Applicable
Document (7)). A notation that starts with "DF" in the column "Remarks" indicates the
corresponding Data Field in the documentation of RTCM version 10403.2 (Applicable Document
(7)).
(1) GPS (Message Type Number: 1061)
The contents of SSR GPS URA quality information Messages are shown in Table 5.7.2-17.
6
Table 5.7.2-17 SSR GPS URA Messages (Message Type Number: 1061)
Data No. of
Name
Possible range Contents
Type
Bits
0 ~ 4095
Message Number
uint 12
12
SSR Message Type Number
(Value:1057)
GPS reference time (Full
GPS Epoch Time
uint 20
20
0 ~ 604799[s] seconds since the beginning of
1s
the GPS week)
0 ~ 15
SSR
Update
The SSR Update Intervals for
bit (4)
4
(Value:5(=30
Interval
this message.
[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
bit (1)
1
0 or 1
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Issue Of Data number for SSR in
IOD SSR
uint 4
4
0 ~ 15
this message.
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 6
6
0 ~ 63
#
1
2
3
4
5
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
Remarks
DF002
DF385
DF391
DF388
DF413
DF414
DF415
DF387
67
#9 and #10 are repeated for each satellites (1 ~ NS (No. of Satellites: see #8))
9
GPS Satellite ID
uint 6
6
1 ~ 32
10
SSR URA
bit (6)
6
bits 3~5: 0~7
bits 0~2: 0~7
Subtotal (#9+#10)
Total
12
67 + 12 × NS
173
GPS Satellite ID
SSR User Range Accuracy
(URA) (1 sigma) represented by
a combination of URA_CLASS
(high 3 bits) and URA_VALUE
(low 3 bits).
DF068
DF389
IS-QZSS Ver. 1.6
(2) QZSS (Message Type Number: 1250)
The contents of SSR QZSS URA quality information Messages are shown in Table 5.7.2-17.
6
Table 5.7.2-18 SSR QZSS URA Messages (Message Type Number: 1250)
Data No. of
Name
Possible range Contents
Type
Bits
0 ~ 4095
Message Number
uint 12
12
SSR Message Type Number
(Value:1057)
QZSS Reference time (Full
QZSS Epoch Time
uint 20
20
0 ~ 604799[s] seconds since the beginning of
1s
the GPS week)
0 ~ 15
SSR
Update
The SSR Update Intervals for
(Value:5
bit (4)
4
Interval
this message.
(=30[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
bit (1)
1
0 or 1
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Issue Of Data number for SSR in
IOD SSR
uint 4
4
0 ~ 15
this message.
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 4
4
0 ~ 10
#
1
2
3
4
5
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
DF002
*
DF391
DF388
DF413
DF414
DF415
*
67
#9 and #10 are repeated for each satellites (1 ~ NS (No. of Satellites: see #8))
QZSS Satellite ID (See Table
9
QZSS Satellite ID
uint 4
4
1 ~ 10
5.7.2-9)
SSR User Range Accuracy
(URA) (1 sigma) represented by
bits 3~5: 0~7
a combination of URA_CLASS
10 SSR URA
bit (6)
6
bits 0~2: 0~7
(high 3 bits) and URA_VALUE
(low 3 bits).
Subtotal (#9+#10)
12
Total
Remarks
67 + 12×NS
* Defined in draft version of RTCM.
174
*
DF389
IS-QZSS Ver. 1.6
(3) Galileo (Message Type Number: 1244)
The contents of SSR Galileo URA quality information Messages are shown in Table 5.7.2-17.
6
Table 5.7.2-19 SSR Galileo URA Messages (Message Type Number: 1244)
Data No. of
Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
GALILEO Reference time (Full
GALILEO Epoch
uint 20
20
0 ~ 604799[s] seconds since the beginning of *
Time 1s
the GALILEO week)
0 ~ 15
SSR
Update
The SSR Update Intervals for
(Value:5
bit (4)
4
DF391
Interval
this message.
(=30[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Issue Of Data number for SSR in
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 6
6
0 ~ 63
#
1
2
3
4
5
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
DF387
67
#9 and #10 are repeated for each satellites (1 ~ NS (No. of Satellites: see #8))
GALILEO
9
uint 6
6
0 ~ 63
GALILEO Satellite ID
Satellite ID
SSR User Range Accuracy
(URA) (1 sigma) represented by
bits 3~5: 0~7
a combination of URA_CLASS
10 SSR URA
bit (6)
6
bits 0~2: 0~7
(high 3 bits) and URA_VALUE
(low 3 bits).
Subtotal (#9+#10)
12
Total
DF415
67 + 12 × NS
* Defined in draft version of RTCM.
175
*
DF389
IS-QZSS Ver. 1.6
(4) GLONASS (Message Type Number: 1067)
The contents of SSR GLONASS URA quality information Messages are shown in Table
5.7.2-17.
6
Table 5.7.2-20 SSR GLONASS URA Messages (Message Type Number: 1061)
Data No. of
Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
GLONASS reference time (Full
GLONASS Epoch
uint 17
17
0 ~ 86400 [s] seconds since the beginning of DF386
Time 1s
the GLONASS day)
0 ~ 15
SSR
Update
The SSR Update Intervals for
(Value:5
bit (4)
4
DF391
Interval
this message.
(=30[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
bit (1)
1
0 or 1
DF388
Number and Epoch Time (1:
Indicator
multiple message transmitted)
Issue Of Data number for SSR in
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 6
6
0 ~ 63
#
1
2
3
4
5
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
DF387
67
#9 and #10 are repeated for each satellites (1 ~ NS (No. of Satellites: see #8))
GLONASS
9
uint 5
5
1 ~ 24
GPS Satellite ID
Satellite ID
SSR User Range Accuracy
(URA) (1 sigma) represented by
bits 3~5: 0~7
10 SSR URA
bit (6)
6
a combination of URA_CLASS
bits 0~2: 0~7
(high 3 bits) and URA_VALUE
(low 3 bits).
Subtotal (#9+#10)
12
Total
DF415
67 + 12 × NS
176
DF068
DF389
IS-QZSS Ver. 1.6
5.7.2.2.5.5 SSR Clock Correction Messages
The contents of SSR High Rate Clock Correction Messages for GPS, GLONASS, QZSS and
Galileo is shown below.
To reduce the quantity of data, content and format of some of the items do not always follow
RTCM standards version 10403.2 (Applicable Document (7)). You can see the difference of the
definition of the parameter between MADOCA-LEX and RTCM10403.2 (Applicable Document
(7)) in section 6.5.2.2. A notation that starts with "DF" in the column "Remarks" indicates the
corresponding Data Field in the documentation of RTCM version 10403.2 (Applicable Document
(7)).
(1) GPS (Message Type Number: 1062)
The contents of SSR GPS High Rate Clock Correction Messages are shown in Table 5.7.2-21.
Table 5.7.2-21 SSR GPS High Rate Clock Correction Messages (Message Type Number: 1062)
Data No. of
# Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
1
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
GPS reference time (Full
GPS Epoch Time
2
uint 20
20
0 ~ 604799[s] seconds since the beginning of DF385
1s
the GPS week)
0 ~ 15
SSR
Update
The SSR Update Intervals for
(Value:1
3
bit (4)
4
DF391
Interval
this message.
(=2[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
4
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Issue Of Data number for SSR in
5
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
6
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 6
6
0 ~ 63
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
DF415
DF387
67
#9 and #10 are repeated for each satellites (1 ~ NS (No. of Satellites: see #8))
9
10
GPS Satellite ID
High Rate Clock
Correction
Subtotal (#9+#10)
Total
uint 6
6
int 22
22
1 ~ 32
±209.7151
[m]
28
67 + 28 × NS
177
GPS Satellite ID
High Rate Clock correction
Value
DF068
DF390
IS-QZSS Ver. 1.6
(2) QZSS (Message Type Number: 1248)
The contents of SSR QZSS High Rate Clock Correction Messages are shown in Table 5.7.2-21.
Table 5.7.2-22 SSR QZSS High Rate Clock Correction Messages (Message Type Number: 1248)
Data No. of
# Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
1
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
QZSS Reference time (Full
QZSS Epoch Time
2
uint 20
20
0 ~ 604799[s] seconds since the beginning of *
1s
the GPS week)
0 ~ 15
SSR
Update
The SSR Update Intervals for
(Value:1
3
bit (4)
4
DF391
Interval
this message.
(=2[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
4
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Issue Of Data number for SSR in
5
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
6
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 4
4
0 ~ 10
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
*
67
#9 and #10 are repeated for each satellites (1 -–NS (No. of Satellites: see #8))
QZSS Satellite ID (See Table
9
QZSS Satellite ID
uint 4
4
1 ~ 10
5.7.2-9)
High Rate Clock
±209.7151
High Rate Clock correction
10
int 22
22
Correction
[m]
Value
Subtotal (#9+#10)
28
Total
DF415
67 + 28 × NS
* Defined in draft version of RTCM.
178
*
DF390
IS-QZSS Ver. 1.6
(3) Galileo (Message Type Number: 1242)
The contents of SSR Galileo High Rate Clock Correction Messages are shown in Table 5.7.2-21.
#
1
2
3
4
5
6
Table 5.7.2-23 SSR Galileo High Rate Clock Correction Messages (Message Type Number:
1242)
Data No. of
Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
GALILEO Reference time (Full
GALILEO Epoch
uint 20
20
0 ~ 604799[s] seconds since the beginning of *
Time 1s
the GALILEO week)
0 ~ 15
SSR
Update
The SSR Update Intervals for
bit (4)
4
(Value:1
DF391
Interval
this message.
(=2[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Issue Of Data number for SSR in
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 6
6
0 ~ 63
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
DF387
67
#9 and #10 are repeated for each satellites (1 ~ NS (No. of Satellites: see #8))
GALILEO
9
uint 6
6
0 ~ 63
GALILEO Satellite ID
Satellite ID
High Rate Clock
±209.7151
High Rate Clock correction
10
int 22
22
Correction
[m]
Value
Subtotal (#9+#10)
28
Total
DF415
67 + 28 × NS
* Defined in draft version of RTCM.
179
*
DF390
IS-QZSS Ver. 1.6
(4) GLONASS (Message Type Number: 1065)
The contents of SSR GLONASS High Rate Clock Correction Messages are shown in Table
5.7.2-21.
Table 5.7.2-24 SSR GLONASS High Rate Clock Correction Messages (Message Type Number:
1065)
Data No. of
# Name
Possible range Contents
Remarks
Type
Bits
0 ~ 4095
1
Message Number
uint 12
12
SSR Message Type Number
DF002
(Value:1057)
GLONASS reference time (Full
GLONASS Epoch
2
uint 17
17
0 ~ 86400 [s] seconds since the beginning of DF386
Time 1s
the GLONASS day)
0 ~ 15
SSR
Update
The SSR Update Intervals for
3
bit (4)
4
(Value:1
DF391
Interval
this message.
(=2[s]))
Indicator
for
transmitting
Multiple Message
messages with the same Message
4
bit (1)
1
0 or 1
DF388
Indicator
Number and Epoch Time (1:
multiple message transmitted)
Issue Of Data number for SSR in
5
IOD SSR
uint 4
4
0 ~ 15
DF413
this message.
6
SSR Provider ID
uint 16
16
0 ~ 65535
SSR Provider ID number
DF414
7
SSR Solution ID
uint 4
4
0 ~ 15
8
No. of Satellites
uint 6
6
0 ~ 63
Subtotal (#1 ~ #8)
SSR Solution ID number
Number of Satellites included in
the message
DF387
67
#9 and #10 are repeated for each satellites (1 ~ NS (No. of Satellites: see #8))
GLONASS
9
uint 5
5
1 ~ 24
GPS Satellite ID
Satellite ID
High Rate Clock
±209.7151
High Rate Clock correction
10
int 22
22
Correction
[m]
Value
Subtotal (#9+#10)
28
Total
DF415
67 + 28 × NS
180
DF068
DF390
IS-QZSS Ver. 1.6
5.7.2.2.5.6 Update Interval
You can see the update intervals of the SSR Messages in message type 12 in Table 5.7.2-25.
Table 5.7.2-25 Update intervals of the SSR Messages in message type 12.
Message Type Number
Contents in SSR Packet
Update
Intervals
GPS
QZSS
Galileo
GLONASS
Orbit Correction
1057
1246※
1240※
1063
Code Bias
1059
1248※
1242※
1065
URA
1061
1250※
1244※
1067
30 [sec]
3 [hour] (10800
[sec])
30 [sec]
1062
※
※
1068
2 [sec]
High Rate Clock Correction
1251
1245
* Defined in draft version of RTCM.
5.7.2.2.6 Message Types 13
Message types 13 is also JAXA test message which includes carrier phase bias etc. for real-time
PPP-AR (="Precise Point Positioning with Ambiguity Resolution") calculated by MADOCA.
Further details are to be added in the next update..
181
IS-QZSS Ver. 1.6
6 User Algorithms
6.1 Constants
6.1.1 Speed of Light
Same as Section 20.3.3.3.3.1 in Applicable Document (1).
Expressed using a small letter "c". The value is c = 299792458 [m/s].
6.1.2 Angular Velocity of the Earth's Rotation
Same as Table 20-IV in Applicable Document (1).
 = 7.2921151151467 × 10 −5 [rad/s].
 ". The value is Ω
Expressed using the Greek symbol " Ω
e
e
6.1.3 Earth's Gravitational Constant
Same as Table 20-IV in Applicable Document (1).
Expressed using the Greek symbol "µ". The value is µ = 3.986005 × 10 −5 [m3/s2].
6.1.4 Circular Constant
Same as Section 20.3.3.4.3.2 in Applicable Document (1).
Expressed using the Greek symbol "π". The value is π = 3.1415926535898 .
6.1.5 Semi-Circle
Same as in Applicable Document (1).
Expressed as the circular constant "π" in Section 6.1.4.
1 [semi-circle] = π [rad]
6.2 User algorithms relating to time systems and coordinate systems
6.2.1 User algorithms relating to time systems
QZSS is based on the following time relationships.
(a) Each satellite is operated in accordance with its own SV clock.
(b) All time relationship data (TOW) are generated by the SV clock.
(c) All other data in navigation messages are relative to GPS time.
(d) Navigational messages are transmitted with reference to the SV clock.
182
IS-QZSS Ver. 1.6
6.2.2 User Algorithms relating to Coordinate Systems
6.2.2.1 Earth-Centered, Earth-Fixed (ECEF) Coordinate System Constant
The Earth-Centered, Earth-Fixed (ECEF) coordinate system referred to in this document is defined as
follows.
(a) Origin:
Earth's center of mass
(b) Z-axis:
The direction of the IERS Reference pole
(c) X-axis:
Intersection of the IERS Reference Meridian (IRM) and the plane passing
through the origin and normal to the Z-axis
(d) Y-axis:
Completes a right-hand, Earth-centered, Earth-Fixed orthogonal coordinate
system
6.2.2.1.1 QZSS Earth-Centered, Earth-Fixed (ECEF) Coordinate System
The Earth-Centered, Earth-Fixed (ECEF) coordinate system used by QZSS is known as the Japan
satellite navigation Geodetic System (JGS). It is defined in Section 3.1.4.2.
6.2.2.1.2 Relationship between GPS Earth-Centered, Earth-Fixed (ECEF) coordinate system
and QZSS ECEF coordinate system
The GPS Earth-Centered, Earth-Fixed (ECEF) coordinate system is known as the World Geodetic
System 1984 (WGS84). It is defined Section 20.4.3.3.1 in Applicable Document (1).
The relationship between WGS84 and JGS is covered in Section 3.2.2.
6.2.2.1.3 Differences in JGS and WGS84 ellipsoids and the effect of these differences
JGS uses the Geodetic Reference System 1980 (GRS80) ellipsoid, while WGS84 uses the WGS84
ellipsoid. The differences between these ellipsoids affect primarily the angle of elevation calculation
that must be performed in the process of calculating the ionospheric delay correction. However, as
these two ellipsoids are virtually identical, in practical terms there is no difference.
(a) GRS80 ellipsoid
a = 6,378,137 [m], f = 1/298.257222101
(b) WGS84 ellipsoid
a = 6,378,137 [m], f = 1/298.257223563
6.2.2.2 Satellite position as determined by orbit calculations
The positions of the satellites in each system as determined in Section 6.3.5 indicate the antenna phase
center position in the Earth-Centered, Earth-Fixed (ECEF) coordinate system defined by each system
as noted in Section 6.2.2.1.
183
IS-QZSS Ver. 1.6
6.3 Common GNSS Algorithms
6.3.1 Time Relationships
6.3.1.1 Value Calculated using Time
Many parameters relating to satellite status change over time. These parameters are time functions
that have coefficients in the navigation messages and are calculated by the user. Calculations are a
function of the difference in epoch between the current time and each of the parameters. These
parameters include the following:
(a) SV clock correction (Section 6.3.2)
(b) Satellite orbit calculation
(c) UTC (Section 6.3.7)
t k , M k , Ek , vk , Φ k , u k , rk , ik , Ω k (Section 6.3.5 and 6.3.6)
6.3.1.2 Epoch Set at Master Control Station
In general, these epochs are established by the Master Control Station (MCS) as follows.
(1) toe: Ephemeris data epoch
The minimum update period for Ephemeris data is 15 minutes. The curve fit interval and the
validity period are two hours (at minimum). The epoch is set near the center of the curve fit
interval and the validity period. The starting point of the validity period is the update time of
Ephemeris data.
Even if the updating period and the curve fit interval are extended, this relationship (of the
epoch being set near the middle of the curve fit interval) will be maintained.
(2) toc: SV clock parameter epoch
The minimum update period for SV clock parameters is 15 minutes. The validity period is 30
minutes. The epoch is the same as the epoch for the Ephemeris data that are transmitted at the
same time. The starting point of the validity period is the update time of SV clock parameter.
Even if the updating period and the validity period are extended, this relationship (of the epoch
being the same as that of the Ephemeris data) will be maintained.
(3) toa: Almanac data epoch
The Almanac data would be updated by the MCS at least once every 6 days (nominal case:
once a day) while the MCS is able to upload the SVs. The curve fit interval and the validity
period are 24 hours (at minimum). The almanac would be updated often enough to ensure that
current time, t, will differ from toa by less than 3.5 days during the transmission period. The
epoch is set near the center of the curve fit interval and the validity period. The starting point
of the validity period is the update time of Almanac data.
Even if the updating period and the curve fit interval are extended, this relationship (of the
epoch being set near the middle of the curve fit interval) will be maintained.
(4) tot: UTC parameter epoch
The UTC parameters would be updated by the MCS at least once every six days (nominal case:
once a day) while the MCS is able to upload the SVs. The UTC parameters would be updated
often enough to ensure that current time, t, will differ from tot by less than 3.5 days during the
transmission period.
184
IS-QZSS Ver. 1.6
6.3.1.3 Consideration for Week Overlap on the Part of the User
Same as in Applicable Documents (1), (2) and (3).
When implementing the user algorithms in Sections 6.3.2, 6.3.5, 6.3.6, etc., when it is necessary to
determine the interval, (tinterval = t ‒ t0), between the current time, t, and the epoch time, t0, the week
beginning/end overlap should be taken into account using the following equations:
(a) When t ‒ t0 ≥ 302400 [s]
(b) When t ‒ t0 ≤ ‒302400 [s]:
(c) At all other times:
tinterval = t ‒ t0 ‒ 604800 [s]
tinterval = t ‒ t0 + 604800 [s]
tinterval = t ‒ t0
185
IS-QZSS Ver. 1.6
6.3.2 User Algorithm for SV Clock Offset
In general, the SV Clock Offset algorithm is the same as in Applicable Documents (1), (2) and (3).
However, the following points differ from the algorithms specified for GPS alone.
The QZS orbit time is estimated and predicted using the LC pseudorange derived from the ionospheric
delay-free linear combination (LC) of the L1C/A signal and the L2C signal. The estimation is referenced
to the LC antenna phase center of the QZS L-band transmit antenna (L-ANT).
This algorithm is used when determining the offset between (a) the LC-SV clock, tsv, estimated and
predicted at the LC antenna phase center, and (b) GPST. Single- and dual-frequency-signal users should
perform the SV clock corrections corresponding to each QZS signal as noted in this item and in Sections
6.3.3 and 6.3.4.
The series of equations in (1) and (2) below are simultaneous equations, (i.e., to determine t, it is
necessary to determine ∆tSV (t) and ∆tr (t) using t). However, the values are less than 1 [ms], so the
sensitivity of ∆tSV (t) and ∆tr (t) with respect to t can be ignored.
t = tsv − ∆tsv (t ) = t sv − ∆tc (t ) − ∆tr (t )
where
t:
tSV (t):
∆tSV (t):
∆tc (t):
∆tr (t):
GPST
Estimated time when the QZS signal was transmitted from the LC antenna phase
center
tSV (t) time offset with respect to GPST
tSV (t) time offset of the onboard clock with respect to GPST
tSV (t) time offset (due only to relativistic effects) with respect to GPST
(1) LC-SV Clock Offset at LC Antenna Phase Center
The time offset ∆tc (t) of tSV (t) with respect to GPST, not including relativistic effects, is
expressed as follows:
∆tc (t) = af0 + af1 (t ‒ toc) + af2 (t ‒ toc)2
where
t:
toc:
af0, af1, af2:
GPST
Epoch of SV clock parameter. This is provided in Subframe 1 in the case
of the L1C/A signal, in Message Types 30, 31, 32, 33, 34, 35 and 37 in
the case of the L2C and L5 signals, and in Subframe 2 in the case of the
L1C signal.
SV clock parameters. These are provided in Subframe 1 in the case of
the L1C/A signal, in Message Types 30, 31, 32, 33, 34, 35, and 37 in
the case of the L2C and L5 signals, and in Subframe 2 in the case of the
L1C signal.
186
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(2) Relativistic Effect Correction at LC-SV Clock Offset
The time offset ∆tr (t) of tSV (t) with respect to GPST due to the relativistic effect is expressed
as follows:
∆t r (t ) = Fe A sin E k (t ) = −
2 P(t ) ⋅ V (t )
c2
where
F =−
2 µ Constant, determined from the constants shown in Section 6.1.1 and
: Section 6.1.3.
c2
e, A :
Ek (t ) :
P(t ),V (t ) :
Provided in Subframes 2 and 3 in the case of the L1C/A signal, in
Message Types 10 and 11 in the case of the L2C and L5 signals, and
in Subframe 2 in the case of the L1C signal.
Eccentric anomaly at t on the GPST time scale. Determined in
accordance with Section 6.3.5.
The vectors of QZS position and velocity at t on the GPST time scale.
Determined in accordance with Section 6.3.5. Even if these vectors are
calculated by which of the coordinate system in Section 6.2.2.1 and
the geocentric inertial coordinate system, ∆tr(t) becomes the same
value.
6.3.3 Ionospheric Delay Correction for Dual Frequency Users
6.3.3.1 For L1C/A and L2C Dual Frequency Users
L1C/A and L2C dual frequency users should correct the ionospheric delay using the following
equation:
PRL 2 C − L1C / A =
=
(PRL2C + c(∆tsv )L2C ) − γ 12 (PRL1C/A + c(∆tsv )L1C/A )
1 − γ 12
(PRL2C − γ 12 PRL1C/A ) + c(ISCL 2C − γ 12 ISCL1C / A ) − cT
1 − γ 12
PRL2C − L1C/A :
PRL1C/A , PRL2C :
GD
+ c∆t sv
Pseudorange corrected using the ionospheric delay and the SV clock
parameters
Pseudorange measured using the signal indicated by the subscript
2
γ 12
c:
 154 
=
 :
 120 
Square of the ratio between the two signal frequencies
Speed of light as indicated in Section 6.1.1
187
IS-QZSS Ver. 1.6
6.3.3.2 For L1C/A and L5 Dual Frequency Users
L1C/A and L5 dual frequency users should correct the ionospheric delay using the following equation:
PRL5I5 − L1C/A =
(PRL5I5 + c(∆tsv )L5I5 ) − γ 15 (PRL1C/A + c(∆tsv )L1C/A )
1 − γ 15
=
PRL5Q5 − L1C/A =
(PRL5I5 − γ 15 PRL1C/A ) + c(ISCL5I5 − γ 15 ISCL1C/A ) − cT
(PR
L5Q5
1 − γ 15
− γ 15 PRL1C/A ) + c (ISC L5Q5 − γ 15 ISC L1C/A )
1 − γ 15
GD
+ c∆t sv
− cTGD + c∆t sv
where
PRL5I5‒L1C/A, PRL5Q5‒L1C/A :
PRL1C/A, PRL5I5, PRL5Q5:
Pseudorange corrected using the signals indicated by the
subscripts using ionospheric delay and SV clock correction
parameters
Pseudorange measured using the signal indicated by the
subscript
2
γ 15
 154 
=
 :
 115 
c:
Square of the ratio between the two signal frequencies
Speed of light as indicated in Section 6.1.1
6.3.3.3 L2C and L5 Dual Frequency Users
L2C and L5 dual frequency users should correct the ionospheric delay using the following equation:
PRL5I5 − L2C =
=
PRL5Q5 − L2C =
(PRL5I5 + c(∆tsv )L5I5 ) − γ 25 (PRL2C + c(∆tsv )L2C )
1 − γ 25
(PRL5I5 − γ 25 PRL2C ) + c(ISCL5I5 − γ 25 ISCL 2C ) − cT
1 − γ 25
(PRL5Q5 − γ 25 PRL2C ) + c(ISCL5Q5 − γ 25 ISCL 2C )
1 − γ 25
GD
+ c∆t sv
− cTGD + c∆t sv
where
PRL5I5‒L2C, PRL5Q5‒L2C:
PRL2C, PRL5I5, PRL5Q5:
Pseudorange corrected using the signals indicated by the
subscripts using ionospheric delay and SV clock correction
parameters
Pseudorange measured using the signal indicated by the
subscript
2
γ 25
c:
 120 
=
 :
 115 
Square of the ratio between the two signal frequencies
Speed of light as indicated in Section 6.1.1
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6.3.3.4 L1C and L2C Dual Frequency Users
L1C and L2C dual frequency users should correct the ionospheric delay using the following equation.
PRL2C − L1C =
=
(PRL2C + c(∆tsv )L2C ) − γ 12 (PRL1C + c(∆tsv )L1C )
1 − γ 12
(PRL2C − γ 12 PRL1C ) + c(ISCL 2C − γ 12 ISCL1C ) − cT
1 − γ 12
GD
+ c∆t sv
where
PRL2C‒L1C:
PRL2C, PRL1C:
Pseudorange corrected using the signals indicated by the subscripts using
ionospheric delay and SV clock correction parameters
Pseudorange measured using the signal indicated by the subscript (L1CP
signal or L1CD signal in the case of the L1C signal)
2
γ 12
 154 
=
 : Square of the ratio between the two signal frequencies
120


c:
Speed of light as indicated in Section 6.1.1
6.3.3.5 L1C and L5 Dual Frequency Users
L1C and L5 dual frequency users should correct the ionospheric delay using the following equation:
PRL5 − L1C =
=
(PRL5 + c(∆tsv )L5 ) − γ 15 (PRL1C + c(∆tsv )L1C )
1 − γ 15
(PRL5 − γ 15 PRL1C ) + c(ISCL5 − γ 15 ISCL1C ) − cT
1 − γ 15
GD
+ c∆t sv
Pseudorange corrected using the signals indicated by the subscripts using
ionospheric delay and SV clock correction parameters
Pseudorange measured using the signal indicated by the subscript (L1CP
signal or L1CD signal in the case of the L1C signal; L5I signal or L5Q
signal in the case of the L5 signal)
PRL5‒L1C:
PRL1C, PRL5:
2
γ 15
c:
 154 
=
 : Square of the ratio between the two frequencies
 115 
Speed of light as indicated in Section 6.1.1.
189
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6.3.4 Correction of Inter-Signal Group Delay Error by Users of Only One Signal
The inter-signal group delay error terms (TGD, ISCL1C/A, ISCL1CP, ISCL1CD, ISCL2C, ISCL5I5 and ISCL5Q5)
are based on the relationship between the L1C/A signal and the L2C signal in accordance with the
measurements of the satellite currently under consideration. These terms indicate the difference in intergroup delay error between these signals and the L1CD, L1CP, L2C, L5I and L5Q signals.
The standard for ∆tSV, as shown in Section 6.3.2, is determined based on the LC estimated distance
obtained through the ionospheric delay free linear combination using the L1C/A signal and the L2C
signal. Accordingly, single frequency users should use the following equation to correct the value:
From the definitions for ∆tSV and TGD, the values of ISCL1C/A in navigation message is as follows:
ISC L1C/A = 0
6.3.4.1 Correction of Inter-Signal Group Delay Error for L1C/A Signal
(∆t sv )L1C/A = ∆t sv − TGD + ISC L1C/A = ∆t sv − TGD
TGD : Provided by in Subframe 1
6.3.4.2 Correction of Inter-Signal Group Delay Error for L2C Signal
(∆t sv )L 2C
= ∆t sv − TGD + ISC L 2 C
TGD , ISC L 2 C : Provided in Message Type 30
6.3.4.3 Correction of Inter-Signal Group Delay Error for L5 Signal
(∆t sv )L5 I 5 = ∆t sv − TGD + ISC L5 I 5
(∆t sv )L5Q5 = ∆t sv − TGD + ISC L5Q5
TGD , ISC L 5I 5 , ISC L 5Q 5 : Provided in Message Type 30
6.3.4.4 Correction of Inter-Signal Group Delay Error for L1C Signal
(∆t sv )L1CP = ∆t sv − TGD + ISC L1CP
(∆t sv )L1CD = ∆t sv − TGD + ISC L1CD
TGD , ISC L1CP , ISC L1CD : Provided in Subframe 2
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IS-QZSS Ver. 1.6
6.3.5 Calculation of Satellite Orbit using Ephemeris Data
The MCS estimates the QZS orbit in accordance with the virtual LC pseudorange obtained through
ionospheric delay-free linear combination using the L1C/A signal and the L2C signal. Based on various
QZS models, the MCS propagates the orbit value in its generation of navigation messages. During this
process, the LC antenna phase center of the L1C/A and L2C signals is the reference for estimates,
predictions and navigation messages.
The algorithm for calculations of LC antenna phase center of QZS-1 calculations using Ephemeris Data
is as follows:
(1) L1C/A signals
Positioning Calculation algorithms with Ephemeris data of L1C/A signal is the same as in table
20-IV of Applicable document (1).
(2) L1C signals, L2C signals and L5 signals
Positioning Calculation algorithms with Ephemeris data of L1C signals, L2C signals and L5
signals are the same as in table 30-II of Applicable document (1) except following point. (You
should use the same value with GPS (Ex. the reference value of change rate for right ascension

) = –2.6×10–9[semi-circles/second])).
of ascending node ( Ω
REF
(a) The reference value of Semi-Major Axis
AREF = 42164200[m]
6.3.6 Calculation of Satellite Orbit and SV Clock Offset using Almanac Data
Almanac Data can be used for the rough calculation of predictions for SV clock offset and satellite orbit.
6.3.6.1 Almanac Data
(1) L1C/A signal almanac and Midi almanac (L1C, L2C, L5)
The algorithm for satellite orbit calculations using L1C/A signal Almanac Data and Midi
Almanac Data are the same as the algorithm using Ephemeris Data as noted in Table 20-IV of
Section 20.3.3.4.3 of Applicable Document (1), with the following exceptions:
(a) Setting to Zero
All parameters present in Ephemeris Data and not present in Almanac Data should be set to
"0".
(b) Calculation of orbit Inclination Angle
In the case of QZSS: i a = 0.25 + δ i [semi-circle]
In the case of GPS:
i a = 0.3 + δ i [semi-circle]
ia:
Actual inclination value
δi:
Inclination value included in navigation message
(c) Calculation of Eccentricity (unique to QZSS)
In the case of QZSS: ea = 0.06 + enav
In the case of GPS: ea = 0.0 + enav
ea :
enav:
Actual eccentricity value
Eccentricity value included in navigation message
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IS-QZSS Ver. 1.6
(2) Reduced almanac (L1C, L2C and L5 signals)
The algorithm for satellite orbit calculations using Reduced Almanac Data is the same as the
algorithm using Ephemeris Data as noted in Table 30-II of Applicable Document (1), with the
following exceptions:
(a) Setting to Zero
All parameters present in Ephemeris Data and not present in Almanac Data should be set to
"0".
(b) Calculation of Semi-Major Axis
For QZSS: A = 42,164,200 m + δ A
For GPS:
[ ]
A = 26,559,710[m] + δ A
δA : Semi-Major Axis value included in navigation message
(c) Eccentricity
For QZSS: ea = 0.075 [-]
For GPS: ea = 0.0 [-]
Actual eccentricity value
ea:
(d) Orbit Inclination Angle
For QZSS: ia = 43 [deg] (= 0.2389 [semi-circles])
For GPS: ia = 55 [deg] (= 0.3056 [semi-circles])
Actual Inclination Angle
ia:
(e) Change rate in Right ascension of ascending node (RAAN)
 = −8.7 × 10 −10 [semi-circles/seconds]
For QZSS: Ω
For GPS:
 = −2.6 × 10 −9 [semi-circles/seconds]
Ω
(f) Argument of Perigee
For QZSS: ω = 270.0
[deg] (= –0.5 [semi-circles])
ω = 0.0 [deg ] (= 0 [semi-circles])
For GPS:
(3) The satellite positioning accuracy resulting from Almanac Data
The satellite positioning accuracy resulting from Almanac Data is in accordance with
Applicable Document (1) in the case of GPS, and Sections 5.2.2.2.5.2 (2) (a), 5.5.2.2.4.5 and
5.5.2.2.4.6 in the case of QZSS.
6.3.6.2 Almanac Reference Time (toa) and Almanac Reference Week Number (WNa)
Note that the Almanac reference time may not be updated even if the Almanac data has been updated.
The L1C/A signal is the same as GPS as noted in Section 5.2.2.2.5.1 in that the concept of pages does
not exist. For this reason, it is impossible to guarantee when Almanac data updating may occur. For
more information on the Almanac reference Week Number corresponding to Almanac reference time,
see Section 5.2.2.2.5.2(5).
6.3.6.3 Calculation of Satellite SV Clock Offset using Almanac Time Data
Almanac time data can be used for the rough calculation of prediction of the SV clock offset. The
reduced Almanac is not included in the Almanac time data.
Of these, the Almanac time data comprise an 11-bit constant (af0) and an 11-bit (10-bit for the CNAV
and CNAV2 message) primary term (af1). These data can be used to determine the satellite time offset
with respect to GPS time. The algorithm used to calculate the SV clock offset using Almanac time
data is the same as the algorithm using Ephemeris data specified in Section 6.3.2(1), with the
following exceptions.
(a) Setting to zero
Parameter af2 that is present in Ephemeris data and not present in Almanac data should be set
to "0".
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The SV clock offset accuracy produced by Almanac data is in accordance with Applicable Document
(1) in the case of GPS and Section 5.2.2.2.5.2 (2) (a) in the case of QZSS.
6.3.7 Calculation of Coordinated Universal Time (UTC) using the global standard time parameter
It is possible to use the UTC parameter to convert system time to coordinated universal time (UTC). In
the case of the L1C/A signal, coordinated universal time is UTC (USNO) when the Data-ID is "00"(B)
and UTC (NICT) when the Data-ID is "11"(B). In the case of the L2C and L5 signals, coordinated
universal time is UTC (USNO) in the case of Message Type 49 and UTC (NICT) in the case of Message
Type 33.
The algorithm is the same as in Section 20.3.3.5.2.4 of Applicable Document (1).
6.3.8 Correction of Ionospheric Delay Using Ionospheric Parameters
This is the same as in Section 20.3.3.5.2.5 of Applicable Document (1). Correction can be performed
by determining the ionospheric delay, cTiono, for the L1 frequency and subtracting this value from
measured pseudorange.
2
 154 
 Tiono . The ionospheric delay for the LEX
 120 
The ionospheric delay for the L2 frequency is c
2
2
 154 
 154 
frequency is c
 Tiono . The ionospheric delay for the L5 frequency is c
 Tiono .
 125 
 115 
6.3.9 Correction Using NMCT (L1C/A Signal) and DC Data (L1C, L2C and L5 Signals)
6.3.9.1 Correction Using NMCT (Navigation Message Correction Table) Data
For the L1C/A signal, the Estimated Range Deviation (ERD) value in the NMCT for each satellite is
the estimate of the difference between (a) the measured pseudorange value for each satellite monitored
from the ground by QZSS and (b) the value for pseudorange that is calculated based on the Ephemeris
data and SV clock parameters for each satellite tracked.
ERD is calculated by the MCS. The following equation is used to correct the measured pseudorange
value using the ERD value:
PRC = PRM ‒ ERD
where
PRC:
ERD:
PRM:
Corrected pseudorange value
Estimated range deviation
Measured pseudorange value
193
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6.3.9.2 Correction using DC Data (L1C, L2C and L5 Signals)
In the L1C, L2C and L5 signals, the DC data for each satellite constitute the estimate of the difference
between (a) the measured pseudorange value for each satellite monitored from the ground by the
QZSS MCS and (b) the value for estimated pseudorange that is calculated based on the Ephemeris
data and SV clock parameters for each satellite tracked.
The DC data are calculated by the MCS.
6.3.9.2.1 Use of CDC Data
If the satellite DC data pair (EDC and CDC) can be used, the user may use the CDC data in place
of the algorithm in Section 6.3.2 (1) to perform the LC-SV clock correction referenced to the LC
antenna phase center. In other words, the PRN code phase offset
∆t c (t )
of the satellite time with
respect to QZSST, with the exception of the relativistic effect, is expressed as follows:
∆tc (t ) = (a f0 + δ a f0 ) + (a f1 + δ a f1 )(t − toc ) + a f2 (t − toc )
2
where
t:
toc:
af0, af1, af2:
δ af0, δ af1:
QZSST defined in Section 3.1.4.1
Epoch of SV clock parameter, provided in Subframe 1 in the case of the
L1C/A signal, in Message Types 30, 31, 32, 33, 34, 35 and 37 in the case
of the L2C and L5 signals, and in Subframe 2 in the case of the L1C
signal.
SV clock parameters, provided in Subframe 1 in the case of the L1C/A
signal, in Message Types 30, 31, 32, 33, 34, 35 and 37 in the case of the
L2C and L5 signals, and in Subframe 2 in the case of the L1C signal.
SV clock parameters, provided in Message Types 34 and 13 in the case
of the L2C and L5 signals, and in Subframe 3 in the case of the L1C
signal. This can only be applied when predict time of week for the
Ephemeris Data and the SV Clock Parameters is older than predict time
of week of the DC data (in other words, when the value of top-D is greater
than the value of top).
6.3.9.2.2 Use of EDC Data
If the satellite DC data pair (EDC and CDC) can be used, the user may use the EDC data in place
of the algorithm in Section 6.3.5 to calculate the orbit referenced to the LC antenna phase center.
This user algorithm is the same as the one in Applicable Document (1).
This can only be used when the epoch for the Ephemeris data and the SV clock parameters is older
than the epoch of the DC data (in other words, when the value of top- is greater than the value of top).
6.3.10 User Algorithms Relating to Interoperability with Other Satellite Navigation Systems
TBD
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6.4 L1 SAIF Algorithm
6.4.1 Validity period (Time-out period)
User receivers must keep track of the age-of-data corresponding to each L1-SAIF message parameter.
The contents of the SAIF messages have various validity periods so-called "time-out period" appropriate
to the characteristics of each parameter as shown in Table 6.4.1-1. Any SAIF parameters whose age-ofdata exceeds the corresponding validity period must not be used for navigation. The starting point for
determination of the age-of-data is the second of the GPS epoch time when the first bit of the preamble
for the message including a relevant parameter is transmitted. The validity period is defined in Table
6.4.1-1.
Note that the durations of the validity periods not only vary from message type to message type, they
also can be different for different parameters within the same message type. In particular, Message types
2-6 and 24 include both the Fast Correction parameter (FCi) and its accuracy (UDREIi), and these two
parameters have different validity periods.
Table 6.4.1-1 Validity Periods for L1-SAIF Message Parameters
Message Type ID Contents
Timeout period (s)
0
Test mode
60
1
PRN mask
1200
2 ~ 6, 24
Fast Correction
UDREI
120
12
10
Degradation Parameter
240
12
Timing Information
600
18
IGP mask
24, 25
1200
Long-term Correction
240
Ionospheric Vertical Delay
600
GIVEI
600
28
Clock-ephemeris Covariance
240
52
TGP mask
600
53
Tropospheric Delay Correction
600
56
Inter signal bias correction data
1200
58
QZS ephemeris
26
300
6.4.2 Error Correction Algorithm
6.4.2.1 Clock and Orbit error correction (Long-term correction)
The Long-term correction message (Message type 24, 25) provides parameters for use in correcting
both clock and orbital position errors associated with the corresponding navigation satellite. The clock
offset value ∆tSV,i calculated using the navigation messages transmitted by each GPS or QZS (see
section 20.3.3.3.3.1 and 20.3.3.3.3.2 in Applicable document (1)) is further corrected as follows using
the long-term Clock Error Correction parameter in the SAIF message.
(6.4-1)
corrected
∆t SV
= ∆t SV ,i + δ ∆t SV ,i
,i
where,
δ∆tSV,i [s] is the Clock Error Correction parameter of the Long-term Correction SAIF message.
In addition, the orbital position of the corresponding navigation satellite is corrected as follows using
the long-term Orbital Position correction parameters in SAIF message as well.
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IS-QZSS Ver. 1.6
 xi 
 xi 
δ xi 
y 


=  yi 
+ δ yi 
 i
 zi  corrected  zi  ephemeris δ zi 
(6.4-2)
where,
δxi, δyi and δzi [m] are respectively, the x-, y- and z- Orbital Position Error Correction parameters of
the Long-term Correction SAIF message.
The satellite clock error correction parameter, δΔtsv,i, at any time of day, tk, is calculated using the
following equation. (This parameter is applied to the clock offset calculation in accordance with
equation (6.4-1).)
δ∆t SV ,i (t k ) = δ a i , f0 + δ a i , f1 (t k − t i , LT )
(6.4-3)
where (tk ‒ ti,LT) is corrected for end of day crossover if necessary. If the velocity code = 0, then the
corresponding δai,f1 term should be set to 0. In cases where the augmented navigation satellite signals
are from a different RNSS system, for instance GLONASS, the following equation is to be applied:
δ∆t SV ,i (t k ) = δ ai , f0 + δ ai , f1 (t k − ti , LT ) + δ ai ,GLONASS
(6.4-4)
In this case, the time offset between GPS time and GLONASS, δai,GLONASS, is provided in message
type 12. Users must NOT use GLONASS unless the corresponding time offset parameter is received.
The appropriate correction value from equation (6.4-3) or (6.4-4) is added to the estimated time, Δtsv,
defined in Applicable Document (1).
The orbital position of the corresponding navigation satellite is corrected by adding the correction
vector calculated in equation (6.4-5) to the estimated position vector (see equation (6.4-2)) received
via the broadcast ephemeris data.
δ xGLONASS 
δ xi (t k ) δ xi  δ xi 

δ y (t ) = δ y  + δ y  (t − t ) + δ y
 i k   i   i  k i ,LT  GLONASS 
δ zGLONASS 
δ zi (t k ) δ zi  δ zi 
(6.4-5)
The above correction vector is applied to the same satellite, i, in ECEF coordinates at time, tk. If the
velocity code = 0, then the second term in equation (6.4-5) should be set to 0. The third term in
equation (6.4-5) indicate the parameter to transform from the PZ-90.02 coordinate (employed by
GLONASS) to the WGS-84 (employed by GPS). If you want to calculate the correction value for
GLONASS, you should set δxGLONASS = –0.36, δyGLONASS = 0.08 and δzGLONASS = 0.18. In the case
of GPS calculation, the third tem should be set to 0.
Note that the ephemeris data broadcast in the L1-C/A signal, (i.e., NAV message), MUST be used for
the corrections calculated in equations (6.4-1) and (6.4-2) using data from the L1-SAIF messages.
Ephemeris data provided in the CNAV or CNAV2 messages should NOT be applied to the corrections
performed using the L1-SAIF message data.
6.4.2.2 Fast Correction and Atmospheric Delay Correction
The error correction parameters broadcast in the SAIF messages are used to correct the pseudorange
measurements (between satellite and user receiver). The corrected pseudorange, PRicorrected [m], is
used to compute user position after the SAIF correction parameters are applied to the measured
pseudorange for each observable satellite, PRimeasured [m] using the following equation:
PRicorrected = PRimeasured + FCi + ICi + TC i
196
(6.4-6)
IS-QZSS Ver. 1.6
FCi, ICi, and TCi [m] are the Fast Correction, Ionospheric Delay Correction, and Atmospheric Delay
Correction parameters, respectively. In advance of applying the ionospheric and atmospheric delay
corrections, a rough estimate of user position is required since these delay corrections are dependant
upon position. The Fast Correction parameter is mainly used for the correction of satellite onboard
clock variation. It can be used to correct clock variations ranging from several seconds to several
minutes. The Fast Correction parameter is not a function of user position and its value at any given
time will be identical for all users. Note that the ionospheric and atmospheric delay correction
parameters are not frequently updated.
For a general least-squares position solution, the following projection matrix, S, is used:
 s x ,1
s
y ,1
S=
 s z ,1

 st ,1
s x,2  s x, N 
s y , 2  s y , N 
= GT ⋅W ⋅ G

s z,2  s z, N

st , 2  st , N 
(
)
−1
⋅ GT ⋅W
(6.4-7)
where, G is the matrix which represents the relationship between user position and satellite position:
 − cos EL1 sin AZ 1
 − cos EL sin AZ
2
2
G=



− cos ELN sin AZ N
− cos EL1 cos AZ 1
− sin EL1
− cos EL2 cos AZ 2
− sin EL2


− sin ELN
− cos ELN cos AZ N
1
1


1
(6.4-8)
where ELi [rad] and AZi [rad] are the calculated elevation angle and azimuth, respectively, from the
user to satellite i. AZi is the azimuth angle of the satellite measured from North in a clockwise direction.
The inverse of the weighting matrix, W, is expressed as below:
W −1
σ 12

0
=
 

 0
0
σ 22

0
0 

 0 
  

 σ N2 

(6.4-9)
where σi is the calculated user range error with respect to satellite i.
6.4.2.3 Ionospheric Propagation Delay Correction
6.4.2.3.1 Determination of Pierce Point
In order to calculate an ionospheric delay correction, the ionospheric pierce point (IPP), must first
be determined. The IPP is defined as the point (in the ionospheric layer) where the line between a
satellite and the user receiver intersects the ellipsoidal surface 350 [km] above the WGS84
ellipsoidal surface.
Firstly, the latitude, φ pp, i [rad], of the IPP is calculated using following equation:
φ pp , i = sin -1 (sin φu cosψ pp , i + cos φu sinψ pp , i cos AZ i )
where,
φu [rad] is the latitude of the user receiver, and ψ pp, i
(6.4-10)
[rad] is the angle: IPP - Earth center -
user position, calculated as follows:
ψ pp , i =
 Re

π
− ELi − sin −1 
cos ELi 
2
 Re + hI

197
(6.4-11)
IS-QZSS Ver. 1.6
where ELi [rad] is the elevation angle of satellite; Re [km] is the Earth’s radius (= 6378.137[km]);
and hI is the approximate altitude of ionospheric layer, assumed to be 350 [km].
Next, the longitude, λ pp, i [rad], of the IPP is calculated using one of the following equations:
 sinψ pp , i sin AZ i 
λpp , i = λu + sin -1 

cos φ pp , i


where
λu
(6.4-12)
[rad] is the longitude of the user receiver and the other terms are as defined above.
6.4.2.3.2 Selection of Ionospheric Grid Points (IGP)
The ionospheric delay at an IPP is calculated by interpolation using the ionospheric delay values at
surrounding IGPs. The IGPs are selected in accordance with the IGP mask information provided in
message type 18, independent of the value of delay and GIVE at each IGP. The selection of the
IGPs is implemented with one of the following two procedures:
Procedure a):
If an IPP is surrounded by four IGPs arranged in a rectangular shape separated by 5 degrees in both
latitude and longitude, these surrounding four IGPs are selected for the ionospheric delay correction.
Procedure b):
If an IPP is not surrounded by four IGPs as defined in Procedure a), but is surrounded by three IGPs
arranged in a triangular shape separated by 5 degrees in both latitude and longitude, these
surrounding three IGPs are selected for the ionospheric delay correction.
In cases where an IPP is not surrounded by four or three IGPs, as required for Procedure a) or b),
respectively, the ionospheric delay for that IPP cannot be calculated.
Moreover, if any one of the IGPs selected for Procedure a) or b) above is prohibited from use or
unmonitored, the ionospheric delay at the corresponding IPP cannot be computed. However, in the
case of Procedure a), if only one of the four surrounding IGPs is prohibited from use, then the
remaining three valid IGPs can be used with Procedure b).
6.4.2.3.3 Ionospheric Delay Interpolation at Pierce Point
The ionospheric delay at the IPP is calculated by interpolation using the delays associated with the
four or three IGPs selected using Procedure a) or b), respectively, as described in the previous
section.
The following equation is to be used for interpolation with four IGPs:
τ pp , i (φ pp , i , λ pp , i ) = ∑ Wkτ k
4
(6.4-13)
k =1
The vertical delay at the IPP, τ pp, i [s], is described as a function of the IPP latitude, φ pp, i , and the
IPP longitude, λ pp, i . τ k [s] is the vertical delay at IGP k.
The weighting coefficient at each IGP is computed using x pp =
λ pp , i − λ1
φ pp , i − φ1
, y pp =
as
φ2 − φ1
λ2 − λ1
follows:
W1 = x pp y pp
(6.4-14)
W2 = (1 − x pp )y pp
(6.4-15)
W3 = (1 − x pp )(1 − y pp )
(6.4-16)
W4 = x pp (1 − y pp )
(6.4-17)
198
IS-QZSS Ver. 1.6
The following definitions illustrated in Figure 6.4.2-1 also apply:
λ1 = longitude of IGPs west of IPP
λ2 = longitude of IGPs east of IPP
φ1 = latitude of IGPs south of IPP
φ2 = latitude of IGPs north of IPP
ｙ
φ2
τ2
τ1
User’s IPP
τpp,i（φpp,i ,λpp,i）
Δλpp＝λpp,i－λ1
Δφpp＝φpp,i－φ1
φ1
x
τ3
τ4
λ1
λ2
Figure 6.4.2-1 Definition of interpolation with four surrounding IGPs
The following equation is to be used for interpolation with three IGPs:
τ pp , i (φ pp , i , λ pp , i ) = ∑ Wkτ k
3
(6.4-18)
k =1
The weighting coefficient for each IGP is as follows:
W1 = y pp
(6.4-19)
W2 = 1 − x pp − y pp
(6.4-20)
W3 = x pp
(6.4-21)
As illustrated in Fig. 6.4.2-2, the second weighting coefficient, W2, must be properly determined
from the three IGPs.
199
IS-QZSS Ver. 1.6
ｙ
τ1
φ2
User’s IPP
τpp,i（φpp,i ,λpp,i）
Δλpp＝λpp,i－λ1
Δφpp＝φpp,i－φ1
x
φ1
τ2
τ3
λ1
λ2
Figure 6.4.2-2 Definition of interpolation with three surrounding IGPs
6.4.2.3.4 Computation of Ionospheric Propagation Delay Correction
The slant delay correction value, ICi, is calculated by multiplying the vertical delay at the IPP (as
interpolated from the surrounding IGPs), by the obliquity factor, Fpp.
(
ICi = − Fpp , i ⋅ τ pp , i λ pp , i , φ pp , i
)
(6.4-22)
where,
Fpp , i
  R cos EL
i
= 1 −  e
+
R
h
  e
I




2



−
1
2
(6.4-23)
is the obliquity factor which depends upon the elevation angle from the user receiver to the satellite,
ELi [rad], the Earth radius Re = 6378.137 [km], and the assumed altitude of the ionospheric layer hI
= 350 [km].
6.4.2.4 Zenith Tropospheric Delay Correction
6.4.2.4.1 Correction based on SAIF Message
The message type 53 with TGP block ID n contains ZTDOs at from 34n+1 th to 34(n+1) th TGPs
in the same order as in the effective TGP mask data provided by message type 52.
6 bits ZTDO has a resolution of 0.01 [m] in the range of [–0.32, +0.30 [m]]. "011111"(B) indicates
that ZTDO has not been provided at the corresponding TGP.
200
IS-QZSS Ver. 1.6
By adding the value of Zenith Tropospheric Delay model defined by the following equation 4 at
user position to ZTDO at TGP, Zenith Tropospheric Delay at user position will be obtained.
Note: Units: [mm], Day of Year: doy, Latitude: φ [deg], Height above Sea Level: H [m]
4π
 2π
ZTD[mm] =
2690 + 97 sin 
( doy + 11)  − 6.5φ
( doy − 119 )  + 28sin 
 365.25

 365.25

4π


 2π
+ H ×  −0.31 + 0.023sin 
( doy + 13)  
( doy + 63)  − 0.0071sin 
 365.25

 365.25


(6.4-24)
It is recommended to use ZTDO at a TGP which is within 70 [km] in distance from user. In the case
that plural TGPs are available within this range, it is recommended to use the ZTDOs at up to 3
nearest TGPs.
From the plural ZTDOs at the plural TGPs, it is possible to obtain one Zenith Tropospheric Delay
more suitable for each user position through some interpolation, such as weighted average, etc.
As for the weighting function, the following one could be suggested, where x [km] is a distance
from TGP.
=
w ( x ) 1 ( 0.08 x + 10.0 )
2
(6.4-25)
Tropospheric Delay contained in pseudorange is estimated by multiplying Zenith Tropospheric
Delay and mapping function. Additive inverse of the obtained Zenith Tropospheric Delay is
equivalent to TCi in equation (6.4-6). As for the mapping function, the following equation could be
suggested as an example, where EL [rad] is the elevation of satellites.
m(EL ) =
1.001
(6.4-26)
0.002001 + sin 2 (EL )
TCi in equation (6.4-6) is computed as follows:
nT
∑ w( x
TCi = −m( ELi ）・　k =1
k
) ・ZTDk
(6.4-27)
nT
∑ w( x
k =1
k
)
Where nT is the number of TGPs for tropospheric correction.
6.4.2.4.2 Correction by the model
Tropospheric delay correction may be performed by the model described in Application document
(5).
4
There will be possibility to change about detailed numerical value in future.
201
IS-QZSS Ver. 1.6
6.4.3 Algorithm for Integrity information
Integrity of SAIF message is actually depending on the protection level. It means that the probability
which user positioning error of horizontal and vertical direction is beyond the protection level shall be
specified integrity risk (1 - integrity) or less to (in) the SIS accuracy that has provided by SAIF message
with the signal.
6.4.3.1 Calculation of protection level
Horizontal Protection Level (HPL) and Vertical Protection Level (VPL) is calculated as follows.
HPL = KH · dH
VPL = KV · dV
(6.4-27)
(6.4-28)
Constants are defined by Table 6.4.3-1. "Integrity" in the table means integrity required by the user.
IRI (International Reference Ionosphere) is broadcasting via message type 10.
See the covariance of positioning error as follows.
N
dV2 = ∑ s z2,i ⋅ σ i2
(6.4-29)
i =1
d =
2
H
d x2 + d y2
2
 d x2 − d y2
+ 

2

2

 + d xy2


(6.4-30)
Calculate the each with the following value.
N
d x2 = ∑ s x2,i ⋅ σ i2
(6.4-31)
i =1
N
d y2 = ∑ s y2,i ⋅ σ i2
(6.4-32)
i =1
N
d xy = ∑ s x ,i ⋅ s y ,i ⋅ σ i2
(6.4-33)
i =1
Positioning accuracy σi as for Satellite i is determined as follows.
σ i2 = σ i2, flt + σ i2,UIRE + σ i2,air + σ i2,trop
(6.4-34)
Table 6.4.3-1 Relations of integrity and Constants "K"
Integrity
IRI condition
KH
KV
1–10–7
IRI = 0
5.63
5.33
–6
1–10
IRI ≤ 1
5.26
4.90
1–10–5
IRI ≤ 2
4.80
4.42
1–10–4
IRI ≤ 3
4.29
3.89
–3
IRI ≤ 4
3.72
3.29
1–10
202
IS-QZSS Ver. 1.6
6.4.3.2 Clock and orbit configuration
Correction accuracy of fast and long-term correction is calculated as follow.
σ
2
i , flt
(σ i ,UDREδUDRE + ε ltc )2 , RSSUDRE = 0
= 2
2
2
 σ i ,UDREδUDRE + ε ltc , RSSUDRE = 1
(6.4-35)
As for the long correction degradation, GPS and Geostationary satellite is determined as below.
Note that VC is the velocity code contained long-term correction data.
[
ε ltc
]
C ltc _ lsb + C ltc _ v1 ⋅ max 0, t i , LT − t , t − t i , LT − I ltc _ v1 , VC = 1

t − t ltc
=
,
C ltc _ v 0 ⋅
VC = 0

I
ltc _ v 0

(6.4-36)
Also, QZSS is calculated as follows.
ε ltc = Cqzs _ lsb + Cqzs _ v1 ⋅ max[0, ti , LT − t , t − ti , LT − I qzs _ v1 ]
(6.4-37)
6.4.3.3 Clock―ephemeris covariance
δUDRE in equation (6.4.35) is calculated by following equation with the data in Message type 10 and
28 (Initial value: δUDRE = 1.0)
[
δUDRE = 2e−5 ⋅ I T ⋅ E T ⋅ E ⋅ I + Ccov ariance
]
(6.4-38)
Note: "e" is scale coefficient shown in the message type 28. "I" is the vector which contains unit vector
that indicates the direction of satellite from receiver.
 cos ELi sin AZ i 
cos EL cos AZ 
i
i
I =


sin ELi


1


(6.4-39)
Matrix E is as follows
 E1,1
 0
E=
 0

 0
E1, 2
E2 , 2
0
0
E1,3
E2 , 3
E3,3
0
E1, 4 
E2, 4 
E3, 4 

E4 , 4 
(6.4-40)
6.4.3.4 Ionospheric Propagation Delay
σ2UIRE of equation (6.4-34) is calculated as follows. (UIRE: User Ionospheric Range Error)
σ 2UIRE = F 2 pp ⋅ σ 2UIVE
(6.4-41)
σ2UIVE is interpolated to the specified IPP with σ2GIVE defined at IGPs by user as follows. (UIVE: User
Ionospheric Vertical Error)
σ
4
2
UIVE
= ∑Wn ( x pp ,y pp ) ⋅ σ 2 n ,GIVE
(6.4-42)
n=1
or
203
IS-QZSS Ver. 1.6
3
σ 2UIVE = ∑Wn ( x pp ,y pp ) ⋅ σ 2 n ,GIVE
(6.4-43)
n=1
Note: σ2GIVE is the dispersion model of Ionospheric vertical delay error at IGP.
It can be obtained by GIVEI on table 5.4.3-16.
6.4.3.5 Multipath error
As for σi,air that shows multipath error, use the following model.
σ i ,air =
{0.13 + 0.53 exp(− ELi
10 deg )} + 0.4 2
2
(6.4-44)
6.4.3.6 Tropospheric Propagation Delay
Remained error model of Tropospheric Delay of Satellite i is calculated as follows.
σ i ,trop =
0.12
0.002 + sin 2 (ELi )
(6.4-45)
6.4.4 Calculation of QZSS satellite Position
The position of QZSS satellite can be calculated by numerical integration with position and velocity
given in message type 58. Satellite position is calculated using following equations.
dx
= vx
dt
dy
= vy
dt
dz
= vz
dt
(6.4-46)
(6.4-47)
(6.4-48)
According to the velocity, following equations with perturbation of the acceleration given in message
type 58 can be used.
2
dv x
3 µRe
x
= − 3 µ − J2 5
2
dt
r
r
dv y
dt
dv z
dt
 5z 2 
 2 x + 2Ω
 v + X
1 − 2  x + Ω
e
e y
Q
r 

y
3 µRe2  5 z 2 
 2 y − 2Ω
 v + Y
= − 3 µ − J 2 5 1 − 2  y + Ω
e
e x
Q
2
r
r 
r 
2
3 µRe  5 z 2  
z
= − 3 µ − J 2 5  3 − 2  z + Z Q
2
r
r 
r 
Here, J 2 = 1082625.7 × 10 −9
204
(6.4-49)
(6.4-50)
(6.4-51)
IS-QZSS Ver. 1.6
6.5 LEX Algorithm
6.5.1 Reed Solomon Coding/Decoding Algorithm for LEX Navigation Message
6.5.1.1 Construct Galois Field GF (28)
We choose F ( x ) = x 8 + x 7 + x 2 + x + 1 as a primitive polynomial of degree 8 over Z 2 . (Note
that because this is the binary case, addition (+) is equivalent to exclusive-OR (XOR) and
multiplication (x) is equivalent to the logical AND operation.) When α is a root of F ( x ) = 0 , we
have the following (note that –α8 = α8 over Z 2 ):
α 8 = −α 8 = α 7 + α 2 + α + 1
(6.5-1)
From equation (6.5-1), any power of α can be represented by a linear combination of α7,
α6, α5, α4, α3, α2, α1, α0(= 1) over Z 2 (note that α i + α i = 0 ) as follows:
α8 =α 7 +α 2 +α +1
α 9 = α 8 × α = α 8 + α 3 + α 2 + α = (α 7 + α 2 + α + 1) + α 3 + α 2 + α
=α 7 +α 3 +1
α 10 = α 9 × α = α 8 + α 4 + α = (α 7 + α 2 + α + 1) + α 4 + α
(6.5-2)
=α 7 +α 4 +α 2 +1

α 254 = α 7 + α 6 + α + 1
Then, the order of α is 255 since:
α 255 = α 254 × α = α 8 + α 7 + α 2 + α = (α 7 + α 2 + α + 1) + α 7 + α 2 + α = 1 = α 0
(6.5-3)
From equations (6.5-2), addition of two powers of α is as follows:
When
α m = um7α 7 + um6α 6 +  + um1α 1 + um0α 0
(6.5-4)
α n = un7α 7 + un6α 6 +  + un1α 1 + un0α 0
(6.5-5)
the addition is given by:
α m + α n = (u m7 + u n7 )α 7 + (u m6 + u n6 )α 6 +  + (u m1 + u n1 )α 1 + (u m0 + u n0 )α 0
=αl
(6.5-6)
Each umi, unj coefficient is either a zero or a one, and umi + uni is the logical "exclusive OR" of the two
coefficients. By the above operations, 0,1 = α 0 , α 1 , α 2 ,  , α 254 makes a Galois Field GF (28).
{ (
)
205
}
IS-QZSS Ver. 1.6
6.5.1.2 Change of Basis
{0,1(= α ), α , α
0
From equations (6.5-2), one basis for
1
2
,  , α 254
}
over Z 2 is the set { α7,
α6, α5, α4, α3, α2, α1, α0}.
When l0=α125, l1=α88, l2=α226, l3=α163, l4=α46, l5=α184, l6=α67and l7=α242,
the set
{l0 , l1 , l2 , l3 , l4 , l5 , l6 , l7 }
{ (
)
is another basis for 0,1 = α 0 , α 1 , α 2 ,  , α 254
} over
Z2 .
When the nth power of α is represented by two linear combinations:
α n = u7α 7 + u6α 6 + u5α 5 + u 4α 4 + u3α 3 + u 2α 2 + u1α 1 + u0α 0
(6.5-7)
= z0l0 + z1l1 + z 2l2 + z3l3 + z 4l4 + z5l5 + z6l6 + z7 l7
The relationship between u 7 , u 6 , u 5 , u 4 , u 3 , u 2 , u1 and z0 , z1 , z 2 , z3 , z 4 , z5 , z6 , z7 is given by the
following two equations:
 u7 
 
 u6 
u 
 5
u 
(z0 , z1 , z2 , z3 , z4 , z5 , z6 , z7 ) =  4 
 u3 
 u2 
 
 u1 
 
 u0 
t
1

1
1

1
1

1
1


0
 z0 
 
 z1 
z 
 2
z 
(u 7 , u 6 , u5 , u 4 , u3 , u 2 , u1 , u 0 ) =  3 
 z4 
 z5 
 
 z6 
 
 z7 
t
1

0
0

1
1

0
1

1
0
1
1
0
1
0
0
1
0
1
1
0
1
0
1
1
1
1
0
1
1
1
0
1
1
1
1
0
1
1
1
1
0
0
0
0
1
1
0
1
0
0
1
1
1
1
1
0
0
0
0
1
1
1
0
0
1
1
1
1
0
0
1
0
0
0
1
1
0
1
1
1
0
1
0
1
1
0
1
1
1
0
1
1
0
0
1
1
1

1
0

0
0

1
1

1 
(6.5-8)
0 1

1 0
1 0

0 1
0 0

0 1
0 0

0 0 
(6.5-9)
Each ui, zj coefficient is either a zero or a one, and addition for these matrix operations is simply
"exclusive OR".
206
IS-QZSS Ver. 1.6
6.5.1.3 Encoding
When the Header and Data parts of the LEX message (see Figure 5.7.2-1) are given, the ReedSolomon encoding is performed as follows.
The target encoded length is 214 symbols (5 to 218) followed by the Preamble. Think of the bits in
z0 , z1 , z 2 , z3 , z 4 , z5 , z6 , z7 , corresponding to the elements of
each symbol as
{0,1(= α ), α , α
0
1
2
,  , α 254
}
(see Section 6.5.1.2). When the binary string 5th,6th, ･ ･ ･ ,218th
{ (
)
}
symbol is represented by A5, A6,･･･,A218 ( Ai ∈ 0,1 = α 0 , α 1 , α 2 ,, α 254 ), polynomial I (x )
{ (
)
over 0,1 = α 0 , α 1 , α 2 ,  , α 254
} is defined as follows:
I (x ) = A5 x 213 + A6 x 212 +  + A217 x + A218
(6.5-10)
{ (
)
If the code generator polynomial over 0,1 = α 0 , α 1 , α 2 ,  , α 254
g (x ) =
} is defined as follows:
∏ (x − α )
143
11 j
(6.5-11)
j =112
32
P(x ) is the remainder of dividing x I (x ) by g (x ) . Division is used operation of Galois
Field {0,1(= α 0 ),α 1 , α 2 ,  , α 254 } (see Section 6.5.1.1).
P(x ) is written as follows:
then,
P(x ) = B1 x 31 + B2 x 30 +  + B31 x + B32
{ (
)
Bi ∈ 0,1 = α 0 , α 1 , α 2 ,  , α 254
(6.5-12)
}
When each Bi is represented by a linear combination of set
{l0 , l1 , l2 , l3 , l4 , l5 , l6 , l7 } :
Bi = z0 l0 + z1l1 + z 2l2 + z3l3 + z4 l4 + z5l5 + z6 l6 + z7 l7
(6.5-13)
The 32-symbol Reed-Solomon Code is generated by thinking of z0 , z1 , z 2 , z3 , z 4 , z5 , z6 , z7 as the
bits of the symbol.
6.5.1.4 Decoding
Similarly, in Section 6.5.1.3, the polynomial S ( x ) is generated as follows from the 5th to 250th
symbols of the received message.
′ x + A250
′
S (x ) = A5′ x 245 + A6′ x 244 +  + A249
(6.5-14)
Thus, by employing this R-S encoding/decoding we can detect errors and correct them up until 16
symbol errors occur, by computing 32 polynomials S α 11 j , j = 112 − 143 . If no errors exist,
(
Sα
11 j
)
( )
is all zeroes.
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6.5.2 Considerations for using Message Type 12 (MADOCA-LEX)
6.5.2.1 SSR IOD
In SSR message part in message type 12 (see Section 5.7.2.2.5.1(3)), SSR IOD (4 [bit]) in data part
is incremented when the estimation of orbit and clock (which is the source of generating correction
data) is updated. The user using this message must use SSR messages which have the same SSR IOD.
For other algorithms, please refer to RTCM10403.2 (Applicable Document (7)).
6.5.2.2 Clock Correction
6.5.2.2.1 The difference of the definition of Clock Correction between RTCM and MADOCALEX
In RTCM10403.2 (Applicable Document (7)), the amount of Clock Correction are defined as "the
clock correction value for broadcast satellite clock" (e.g. MT=1058 etc.) updating with low
frequency and "the High Rate Clock correction value for the clock correction value applied to the
broadcast satellite clock" (e.g. MT=1062 etc.) updating with high frequency. The timeline chart of
the transmitting sequence for Clock Correction Messages in RTCM is shown in Figure 6.5.2-1.
HRCC Message
HRCC Message
HRCC Message
HRCC Message
High Rate Clock
HRCC Message
(MT=1062 etc.)
(MT=1062 etc.)
(MT=1062etc.)
(MT=1062 etc.)
Correction (HRCC)
(MT=1062 etc.)
Message HRCC Message
HRCC Message
HRCC Message
HRCC Message
HRCC Message
(MT=1062 etc.)(MT=1062 etc.)
(MT=1062etc.)
(MT=1062 etc.)
(MT=1062 etc.)
(MT=1062 etc.)
Timeline
Clock Correction
Message
(MT=1058 etc.)
Clock Correction
Message
(MT=1058 etc.)
Figure 6.5.2-1 The timeline chart of the transmitting sequence for Clock Correction Messages
in RTCM
Otherwise, in the case of MADOCA-LEX, the clock correction message doesn’t broadcast for
reducing the amount of broadcasting data. MADOCA-LEX broadcasts the High Rate Clock
correction message only.
6.5.2.2.2 Effect for the users
If you correct the satellite clock by your application based on RTCM definition by using MADOCALEX, you would need to transform from MADOCA-LEX to standard RTCM messages. But
MADOCA-LEX does not broadcast "Clock Correction Message"(MT=1058 etc.) (see Table
5.7.2-6). Therefore, you may need to generate "Clock Correction Message" by your application. So
you would need to deal with this issue; for example you would be able to generating "Clock
Correction Message" or "Orbit and Clock Correction Message"(MT=1060 etc.) as follows.
(1) Example 1
In the case of the algorithm which refer to "the clock correction value for broadcast satellite
clock" (MT=1058 etc.) only, you would be able to generate "Clock Correction message"
(MT=1058 etc.) or "Combined Orbit and Clock Correction Message" (MT=1060 etc.) and store
the value of "High Rate Clock Correction" (DF390) to "Delta Clock C0"(DF376) in generated
message.
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IS-QZSS Ver. 1.6
Specifically, in the case of GPS, the contents of header part of "GPS Clock Correction message"
(MT=1058) is same as that of "GPS High Rate Clock Correction Message" (MT=1068). So you
could generate MT=1058 message as follows (See Figure 6.5.2-2):
1. Generate the header part of "GPS Clock Correction message" from "GPS High Rate
Clock Correction Message" you received.
2. Store the value of "High Rate Clock Correction" (DF390) in "GPS High Rate Clock
Correction Message" to "Delta Clock C0"(DF376) in "GPS Clock Correction
message"
3. Store "0" to "Delta Clock C1"(DF377) and "Delta Clock C2"(DF378).
MT1058
New data developed by user
Header part
・・・
DF390→δC0
DF376
δC1 = 0
DF377
δC2 = 0
DF378
Data part
・・・
Figure 6.5.2-2 Example of the generation of "GPS Clock Correction message" (MT=1058) with
Clock Correction information in MADOCA-LEX
(2) Example 2
You would be able to generate dummy (all contents in data part store "0") "Clock Correction
message" for target satellite.
Figure 6.5.2-3 shows the example of the case for GPS.
New data developed by user
MT1062
MT1058
Header part
Header part
・・・
DF376
δC0, δC1, δC2
= all “0”
DF377
＋
Data
part
・・・
DF390
Data part
DF378
・・・
Figure 6.5.2-3 Example of the generation of "GPS Clock Correction message" (MT=1058) with
dummy data.
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IS-QZSS Ver. 1.6
6.6 Other Information
6.6.1 Instrumental Bias in Receivers
It is noted that instrumental bias in receivers should be measured to correct them before shipments.
Navigation results using a combination of various frequency signals may have bias without these
corrections.
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7 Provision of QZSS Operational Information and Data via the Internet
QZSS operational information and data generated and accumulated data at the MCS will be provided to
users via the Internet as specified below.
7.1 QZSS Website for Operational Information and Data
Users can access QZSS operational information and data at the following website ("QZvision").
This QZSS user website has two language choices, Japanese and English for the
international user community.
Japanese and English URL:
http://qz-vision.jaxa.jp/
7.2 Release of QZSS Information and Data
Table 7.2-1 summarizes the QZSS operational information and that will be made publically
available, and how users can access this information. Users can use the data published on
QZ-vision freely because it is same with the data transmitted from satellite.
Category
1
2
3
4
Table 7.2-1 Provision of QZSS Information and Data
Operational Information & Data
Users Access
Notification Advisory
to
QZSS
Users
(NAQU)
Experimental
Schedule (For Step 1:
Demonstration phase)
Evaluation Result for
System Performances
User
Operation
Support Tool
5
Precise Orbit & Clock
6
Detailed Information
for Precise Satellite
Orbit
&
Clock
Estimation
Announcements
regarding
interruption or degradation periods,
(because
of
the
satellite
maintenance
schedule
Orbit
Maintenance
or
Momentum
Management)) constellation status
and malfunction reports for QZSS.
(Similar to NANU for GPS)
Announcement
of
test
and
experiment schedule for users.
URE information, etc.
Freeware, supporting several user
activities such as QZSS & GPS
orbit prediction
Latest almanac, ephemeris data
Navigation pattern table
"Ultra Rapid" and "Final" Products
for both QZSS and GPS
Contact Point for researchers will be
provided on the website.
211
On website
Distribution by e-mail if requested
by users. (Requires E-mail address
registration)
On website
On website
Download from the website a free
User Operation Support Tool that
can be run on a user’s PC.
Download from the website (text
file)
On website
Download from the website (text
file)
How to request detailed information,
including a contact point, will be
described on the website. The
requested will be provided by
electronic media.
IS-QZSS Ver. 1.6
7.2.1 NAQU (NOTICE ADVISORY TO QZSS USERS)
NAQU is the QZSS version of NANU (NOTICE ADVISORY TO NAVSTAR USERS provided by the
United State Coast Guard Navigation Center for GPS users). The QZSS NAQU service will be provided
by JAXA via the QZSS website to inform QZSS users of operational status and planned interruption or
degradation of positioning service (because of the satellite maintenance schedule (Orbit Maintenance or
Momentum Management)), NAQU will also be used to announce unintentional interruptions or
degradation (due to malfunctions or other reasons).
The latest NAQU and several previous NAQUs are provided on the website. Moreover, for QZSS users
who register their e-mail address, the latest NAQU will be sent by e-mail whenever it is posted to the
website.
7.2.2 Experimental Schedule
Daily schedule (of 1 week) for planned experiments using the LEX signal and L1-SAIF signal will be
provided on the website indicated in Section 7.1 above.
7.2.3 Evaluation result for System Performances
The evaluation result of system performance listed in Table 7.2.3-1 is to be provided as on the website
indicated in Section 7.1 above.
No.
1
Table 7.2.3-1 Test Evaluation Public Release Data List
Data
Frequency of Update
URE information etc.
Monthly
7.2.4 User Operation Support Tool
Freeware supporting several user activities such as QZSS & GPS orbit prediction, DOP profile,
generation of assist data, schedule planning, etc., will be provided via the website indicated in Section
7.1 above.
7.2.4.1 User Operation Support Tool (QZ-radar)
Users can download the free software, User Operation Support Tool (UOST) as well as the associated
user’s manual from the website. UOST provides the following functions:
(1) Accept input of user’s location and mask information
(2) Accept input of epoch, simulation time and orbit parameters such as Ephemeris
Data and Almanac Data
(3) Calculate GPS and QZSS position, visible satellites, Doppler frequencies, DOP, etc.
(4) Produce plots and graph resulting from the above calculations
7.2.4.2 Provision of Latest Orbital Information
Via the website, users can download the latest Almanac Data and Ephemeris Data broadcast by QZSS
and GPS.
(1) Almanac Data
The Almanac Data can be downloaded for all satellites (QZSS and GPS (PRN No. = 1 ~ 32))
as well as past archived data.
The data format is YUMA*.
* YUMA: Refer to the Website of "United State Coast Guard"
URL: www.navcen.uscg.gov/?pageName=gpsYuma (11 Dec., 2012)
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(2) Ephemeris Data
The Ephemeris Data can be downloaded for all satellites (QZSS and GPS (PRN No. = 1 ~ 32))
as well as past archived data.
The data format is the same as ephemeris information of RINEX format.
The Ephemeris Data on the website is updated according to the update of broadcast Ephemeris
Data from satellites. Ephemeris Data of GPS is the data extracted from GPS navigation message
received at the Monitor Station.
7.2.4.3 Provision of navigation pattern table
We have made tables of broadcasting order of the data included in each signal (L1C/A, L1C, L2C and
L5) composed of subframes, pages, and messages. We call the tables "Navigation pattern table", and
we have made them for every signal.
We will provide the "navigation pattern table" for L1C/A signal, L1C signal, L2C signal and L5 signal
on the website indicated in Section 7.1 above.
7.2.5 Provision of Precise Orbit & Clock for QZSS and GPS
Users can download the following precise orbit and clock data generated at MCS which are useful for
scientific use, performance evaluation and Precise Point Positioning (PPP).
7.2.5.1 "Final" Satellite Ephemerides and Clocks
The MCS generates the "Final" Satellite Ephemerides and Clocks for GPS (PRN No. = 1 ~ 32) and
QZSS satellites.
The format is the same as the "Final" Satellite Ephemerides and Clocks of the International GNSS
Service (IGS) (SP3 format).
7.2.5.2 "Ultra-Rapid" Ephemerides and Clocks
The MCS generates the "Ultra Rapid" Satellite Ephemerides and Clocks to produce broadcast
Ephemeris Data. They can be downloaded with the same format as IGS "Ultra Rapid" ephemerides
for QZSS (SP3 format).
Users can download the set for GPS (PRN No. = 1 ~ 32) in the same format as IGS "Ultra Rapid"
ephemerides (SP3 format) as well.
7.2.6 Detailed Information for Precise Orbit & Clock Estimation for research purposes
Upon request, users of QZSS information for research purposes will be provided operational
information and data for precise QZSS orbit & clock estimation by electronic file or media (if it is a
large volume).
On the website you can see the contact point for the request.
Since the information is provided by an off-line process by the operator, it may take about at least one
week for users to obtain.
213
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8 Differences with GPS
8.1 Differences in Navigation Messages
The QZSS Navigation Messages for each signal (bit map, number of bits, scale factor,
parameter range and units) are designed to preserve interoperability with GPS to the
greatest extent possible. However, based on differences in the conditions unique to GPS and
QZSS (QZS satellite orbit conditions, etc.), in some cases QZSS Navigation Messages cannot
be expressed using the same definitions as those for GPS. Moreover, in order to provide QZSS
with added value not present in GPS, some content has been intentionally defined differently
from GPS. For this content, the unique QZSS definitions provided below must be used. Table
shows the parameters that have unique QZSS definitions.
8.1.1 Differences with GPS in terms of L1C/A signal
Table 8.1.1-1 Parameters with definitions unique to QZSS in terms of LNAV message (1/2)
Subframe
All
1
Page*1
Parameter
GPS definition
QZSS definition
Anti-Spoof flag
P code encryption flag
Not applicable since there is no
P code in QZSS. AS flag always set
to "0"(B).
Integrity Status Flag
Integrity Assurance Flag
QZS-1 at current MCS does not
adopt this flag ("0"(B) fixed).
C/A or P on L2
L2 code identification
(C/A or P)
"10"(B) fixed since there is no
P code in QZSS.
L2P data flag
P code message (Y/N)
Not applicable ("1"(B) fixed) since
there is no P code in QZSS.
TGD
LCGPS*3 and L1P (Y) group
delay
LCQZSS*4 and L1C/A group delay
Health judged by the rule
described
in
Applicable
document (1)
The issue number of the data set,
Clock. The transmitted IODC
will be different from any value
transmitted by the SV during the
preceding 7 days
Each bit means 1-bit health for
each signal (L1-C/A, L1C, L2, L5
and LEX)
The issue number of the data set,
Clock. The transmitted IODC will
be different from any value
transmitted by the SV during the
preceding 2 days
Ephemeris
Eccentricity (e)
Parameter range is restricted
(0.00 ~ 0.03)
Parameter range is not restricted
(0.00 –Less than 0.5)
Curve Fit Interval
Flag
The validity period for
"0" : 4 hours
"1" : More than 4 hours
NMCT
ERD for SV1-31 except for the
The validity period for
"0" : 2 hours
"1" : more than 4 hours
Not only GPS ERD
(See Table 5.2.2-4)
(User algorithm for NMCT is
different from GPS (See section
5.2.2.2.4 (1))
All
5
bit
Health
(Ephemeris Health)
IODC
2
-
13
ERD
UTC parameter*2
A0, A1
4
18
25
Ionospheric
parameters*2
α0, α1, α2, α3,
β1, β2, β3
A-S flag,
SV conditions
SV itself transmitting that
signal
UTC (USNO)–GPST
relationship
UTC (NICT)–GPST relationship
β0, Optimized for all over the world Optimized for Japan & environs
P code encryption flag and SV
block identification for all GPS
214
Not applicable since there is no
P code in QZSS (not transmitted)
IS-QZSS Ver. 1.6
Table 8.1.1-1 Parameters with definitions unique to QZSS in terms of LNAV message (2/2)
Subframe
4, 5
Page*1
Parameter
Subframe 4
2~5
7 ~ 10
DATA ID
Subframe 5
1 ~ 24
Almanac
eccentricity*2
25
GPS definition
QZSS definition
"01"(B) or "10"(B)
(PRN No.= 1–63)
"00"(B): GPS Almanac (PRN No.=
1-32)
"11"(B): QZS Almanac
"01"(B),"10"(B): Reserved
(QZS-1 at current MCS, the
extension of PRN No. would not be
supported.))
The eccentricity value itself
Difference
with
eccentricity 0.06
Almanac reference
Inclination (i0)*2
i0 = 0.3 [semi-circles].
i0 = 0.25 [semi-circles].
SV health
Health judged by positioning
signal output level
Health judged by positioning
signal C/N at MS
*1 Page numbers for Subframe 4 & 5 in above table is described according to the definition for GPS
*2 QZSS definitions apply to QZS parameters only. GPS satellite parameters conform to GPS definitions.
*3 LCGPS: LCGPS is the ionospheric error free linear combination of the L1P(Y) and L2P(Y) signals for GPS.
*4 LCQZSS: LCQZSS is the ionospheric error free linear combination of the L1C/A and L2C signals for QZSS.
215
referenced
IS-QZSS Ver. 1.6
8.1.2 Differences with GPS in terms of CNAV message on L2C and L5 signals
Table 8.1.2-1 Parameters with definitions unique to QZSS in terms of CNAV message (1/2)
Message
type ID
Parameter
GPS definition
QZSS definition
Common
(12, 13, 14,
28, 31, 34,
37, 47, 53)
PRN number
PRN number for GPS: 1-63
PRN number for GPS: 1-32
(The extension of PRN number for GPS
would not be supported by QZS-1 at
current MCS.)
10,11
Ephemeris Parameters
Validity Term: see applicable
document (1) and (2)
Validity Term: 2 [hours]
Ephemeris
The Reference value of Semi
Major Axis (Aref)*1
26,559,710 [m]
42,164,200 [m]
Ephemeris
Eccentricity (e)
Parameter range is restricted
(0.00 ~ 0.03)
No restrictions on parameter range
(0.00 ~ Less than 0.5)
Integrity Status Flag
Integrity Assurance Flag
QZS-1 at current MCS does not adopt
this flag ("0"(B) fixed).
L2C Phasing
Phase relationship between L2C
and L2P(Y)
QZSS would not adopt this Flag since
there is no P code (fixed at "0"(B)).
Clock Parameters
Validity Term: see applicable
document (1) and (2)
Validity Term: 30 [minutes]
Ionospheric parameters
α0, α1, α2, α3, β0, β1, β,2, β3
Optimized for all over the world
Optimized for Japan & environs
(in case of Message type ID (MTID) =
30)
Optimized for all over the world
(in case of MTID= 46)
TGD
LCGPS*2 and L1P(Y) group delay
LCQZSS*3 and L1C/A group delay
ISCL1C/A
L1P(Y)–L1C/A group delay
L1C/A–L1C/A
group
(Broadcasting value is 0.0)
ISCL2C
L1P(Y)–L2C group delay
L1C/A–L2C group delay
ISCL5I5
L1P(Y)–L5I5 group delay
L1C/A–L5I5 group delay
ISCL5Q5
L1P(Y)–L5Q5 group delay
L1C/A–L5Q5 group delay
The
Reference
value of Semi
Major Axis
(Aref)
Aref = 26,559,710 [m]
Aref = 42,164,200 [m]
(in case of MTID= 31 or 12)
Aref = 26,559,710 [m]
(in case of MTID= 47 or 28)
Eccentricity
(e )
e=0
Inclination (i)
i = 55 [deg]
Change rate in
right
ascension of
ascending
．
．
Ω = –2.6×10–9 [semi-circles/
10
30-35, 37,
46, 47, 49,
51, 53
*1
30 (46)
30
31, 12
(47, 28)
Reduced
Almanac
Precondition*1
e = 0.075
(in case of MTID= 31 or 12)
e = 0 (in case of MTID= 47 or 28)
i = 43 [deg] (in case of MTID= 31 or
12)
i = 55[deg] (in case of MTID= 47 or
28)
．
second]
node (Ω)
Argument of
Perigee (ω)
delay
ω = 0 [deg]
216
Ω = –8.7×10–10 [semi-circles/second]
(in．
case of MTID= 31 or 12)
Ω = –2.6×10–9 [semi-circles/second]
(in case of MTID= 47 or 28)
ω = 270 [deg]
(in case of 31 or 12)
ω = 0 [deg]
(in case of MTID= 47 or 28)
IS-QZSS Ver. 1.6
Table 8.1.2-1 Parameters with definitions unique to QZSS in terms of CNAV message (2/2)
Message
type ID
Parameter
GPS definition
QZSS definition
33 (49)
UTC parameter*1
A0-n, A1-n, A2-n
UTC (USNO)–GPST
relationship
UTC (NICT)–GPST relationship
(in case of MTID= 33)
UTC (USNO)–GPST relationship
(in case of MTID= 49)
35 (51)
GGTO parameter
GNSS ID
"011"(B) means "Reserved" for
GPS
"011"(B) means "QZSS" for QZSS
Difference with QZS eccentricity
0.06 (in case of MTID= 37)
The eccentricity value itself
(in case of MTID= 53)
37(53)

i0 = 0.25 [semi-circles] (in case of
Midi Almanac
MTID=
37)
Reference
i0 = 0.3 [semi-circles].

i
=
0.3
[semi-circles] (in case of
0
*1
Inclination (i0)
MTID= 53)
*1 QZSS definitions apply to QZS parameters only. GPS satellite parameters conform to GPS definitions.
*2 LCGPS is the ionospheric error free linear combination of the L1P(Y) and L2P(Y) signals for QZSS
*3 LCQZSS is the ionospheric error free linear combination of the L1C/A and L2C signals for QZSS
Midi Almanac
Eccentricity*1
The eccentricity value itself
217
IS-QZSS Ver. 1.6
8.1.3 Differences with GPS in terms of CNAV2 message on L1C signals
Table 8.1.3-1 Parameters with definitions unique to QZSS in terms of CNAV2 message (1/2)
Sub Frame# ／
Page#
2/-
3/common (3,
4, 5, 19, 20)
3/1 (or 3/17)
3/2 (or 3/18)
Parameter
GPS definition
QZSS definition*
Ephemeris/
The reference value of Semi
Major Axis (Aref)
26,559,710 [m]
42,164,200 [m]
Ephemeris/
Eccentricity (e)
Parameter range is restricted
(0.00 ~ 0.03)
Parameter range is not restricted
(0.00 ~ Less than 0.5)
ISCL1CP
L1P(Y) – L1CP group delay
L1C/A – L1CP group delay
ISCL1CD
L1P(Y) – L1CD group delay
L1C/A – L1CD group delay
Integrity Status Flag
Integrity Status Flag
QZS-1 at current MCS does not adopt
this flag ("0"(B) fixed).
PRN number for GPS: 1-32
(The extension of PRN number for
GPS would not be supported by QZS1 at current MCS.)
UTC(NICT)–GPST relationship
(if Page 1)
UTC(USNO)–GPST relationship
(if Page 17)
Optimized for Japan & environs
(if Page 1)
Optimized for all over the world
(if Page 17)
PRN number
PRN number for GPS: 1-63
UTC parameter/
A0-n, A1-n, A2-n
UTC(USNO)–GPST
relationship
Ionospheric parameters*1
α0, α1, α2, α3, β0, β1, β2, β3
Optimized for all over the
world
ISCL1C/A
L1P(Y)–L1C/A group delay
L1C/A–L1C/A
group
(Broadcasting value is 0.0)
ISCL2C
L1P(Y)–L2C group delay
L1C/A–L2C group delay
ISCL5I5
L1P(Y)–L5I5 group delay
L1C/A–L5I5 group delay
ISCL5Q5
L1P(Y)–L5Q5 group delay
L1C/A–L5Q5 group delay
GGTO parameter
GNSS ID
"011"(B) means "Reserved" for
GPS
"011"(B) means "QZSS" for QZSS
EOP parameter
(All parameters)
According to section 3.5.4.2.2
in Applicable document (3)
According to section 3.5.4.2.2 in
Applicable document (3) (if Page 2)
Unusable parameters ("0"(B) fixed (all
bit)) (if Page 18)
218
delay
IS-QZSS Ver. 1.6
Table 8.1.3-1 Parameters with definitions unique to QZSS in terms of CNAV2 message (2/2)
Sub Frame#／
Page#
3/3 (or 3/19)
Parameter
Reduced
Almanac
Precondition*
GPS definition
QZSS definition
The
Reference
value
of
Semi Major
Axis (Aref) *
Aref = 26,559,710 [m]
Aref = 42,164,200 (if QZSS, or Page
3)
Aref = 26,559,710 [m] (if GPS
rebroadcasting and Page 19)
Eccentricity
(e)*
e=0
Inclination
(i)*
i = 55 [deg]
Change rate
of
right
ascension of
ascending
．
．
Ω= –2.6 × 10–9
node (Ω)*
Argument of
Perigee
(ω)*
Midi Almanac/
Eccentricity*
．
[semi-circles/second]
ω = 0 [deg]
The eccentricity value itself
3/4 (or 3/20)
Midi Almanac/
Reference Inclination
(i0)*
 e = 0.075 (if QZSS, or Page 3)
 e = 0 (if GPS rebroadcasting and
Page 19)
i = 43[deg] (if QZSS, or Page 3)
i = 55[deg] (if GPS rebroadcasting
and Page 19)
i0 = 0.3 [semi-circles].
Ω = –8.7 × 10–9 [semi-circle/seconds]
(if QZSS,
or Page 3)
．
Ω = –2.6 × 10‒9 [semi-circles/second]
(if QZSS and Page 19)
ω = 270 [deg] (if QZSS, or Page 3)
ω = 0 [deg] (if GPS rebroadcasting
and Page 19)
 The eccentricity value referenced by
0.06 (if QZSS or page 4)
 The eccentricity value itself (if GPS
and page 20)
 i0 = 0.25 [semi-circles] (if QZSS or
page 3)
 i0 = 0.3 [semi-circles] (if GPS and
page 20)
* QZSS definitions apply to QZS parameters only. GPS satellite parameters conform to GPS definitions.
219
IS-QZSS Ver. 1.6
8.2 Difference of RF Characteristics
8.2.1 Difference of Modulated Diffusion Method of Signal
The modulated diffusion method of LIC signal for QZS-1 is BOC (1, 1), and not same as MBOC for
GPS satellite.
8.2.2 Difference of Signal Phase Relation of LIC Signal
The carrier phase relation among L1 QZS-1 signals are defined that L1C/A and L1CD are same and L1CP
is delayed by 90 degrees as described in Section 5.1.1.1.1. L1CD and L1CP for QZS-1 are orthogonal
each other at right angles, but L1CD and L1CP for GPS-III are in phase (Figure 5.1.1-1).
220
IS-QZSS Ver.1.6
ANNEX
Indoor Messaging System (IMES)
IS-QZSS Ver.1.6
A 1 IMES Signal
A 1.1 Indoor Messaging System Signal Overview
IMES (Indoor Messaging System) 1 signal is designed to realize the indoor positioning,
and has a similar property to standard satellite positioning system signal. On the other
hand, the positioning method with IMES signal is totally different from standard satellite
positioning method. This method is very simple and practical for specifying the position
simply by demodulating and decoding the modulated navigation message.
This method requires only a small customization of existing GPS receivers. In this sense,
IMES has similar advantage as QZSS signal and research has been made for the
promotion of QZSS.
QZSS is designed to improve the availability of positioning feasible area and time in both
urban and mountainous area, and IMES is designed to realize the indoor positioning
which is difficult by satellite-based positioning. Both systems are intended to improve the
efficiency and availability of positioning environment, that is to realize the seamless
positioning in both indoor and outdoor environment.
This appendix describes the signal specification of IMES-L1C/A signal which has same RF
characteristics as L1C/A signal and IMES-L1C signal which has same RF characteristics
as L1C signal of GPS and QZSS. Installation of IMES signals transmitter is also explained.
In addition, for operational concept of IMES signals transmitter, please refer to the "IMES
Operational Definition Document [Tentative document title]"(see Section A 1.2 Referenced
document (1)) (in process of creation by IMES consortium).
IMES signal is designed by JAXA to contribute the development of QZSS-ready receivers
as well as satellite positioning applications by realizing the seamless positioning
environment.
However, IMES signal transmitter is not part of the QZSS component, further
development and installation by a third party is expected based on this specification.
Please note that the PRN code set for "IMES" is ONLY authorized by US GPSW to use in
JAPAN, currently. The specification of "IMES Signal" defined in this appendix is only valid
in Japan.
A 1.2 Referenced document
(1) IMES consortium "IMES Operational Definition Document" (under creating process)
A 1.3 IMES signal specification
A 1.3.1 IMES signal -L1C/A type-signal specification
IMES signal -L1C/A type-(IMES-L1C/A) has the same RF characteristic as L1C/A of GPS
and QZSS
Navigation message structure is same in terms of 30 bits word unit, but has frame
structure in terms of one word at the shortest to achieve fast TTRM (Time to Read
Message).
The following describes the specifications by distinguishing RF characteristics and
message characteristics.
1
Patent pending by JAXA, GNSS Technology Inc. and Lighthouse Technology and Consulting Co. (2 patents for "Positional information
providing system, Positional information providing apparatus and transmitter" (Japanese Patent No. 4296302 and 4461235) have been
approved.)
A1
IS-QZSS Ver.1.6
A 1.3.1.1 RF characteristics
A 1.3.1.1.1 Signal structure
A 1.3.1.1.1.1 Nominal center carrier frequency
Nominal center carrier frequency is 1575.4282 [MHz], and deviation is ±0.2 [ppm].
1575.4118 [MHz] is kept for future extension, but only 1575.4282 [MHz] is to be
used today.
A 1.3.1.1.1.2 PRN spreading frequency
PRN spreading frequency is one hundred fifty fourth part of nominal center carrier
frequency. The carrier and PRN code should keep coherence.
A 1.3.1.1.1.3 PRN spreading modulation method
The carrier should be BPSK (1) modulated on CIMES-L1C/A bit strings by PRN code
and navigation message.
A 1.3.1.1.1.4 Frequency bandwidth
2.046 [MHz] or more including main-lobe.
A 1.3.1.1.2 Signal power level
A 1.3.1.1.2.1 Minimum signal power level at the receiver input
The minimum received power measured by the receiving antenna having gain of
0 [dBi] for right-handed circularly polarized wave should be installed and
configured in –158.5 [dBW] or more at the input terminal of receiver having
antenna gain of 0 [dBi] for right-handed circularly polarization.
A 1.3.1.1.2.2 Maximum signal power level at the receiver input
In cases where the power of the receiving GPS signal is estimated in –158.5 [dBW]
or more measured by the receiving antenna having gain of 0 [dBi] for right-handed
circularly polarization, the maximum received power of IMES signal should be
installed and configured in –140 [dBW] or less at the input terminal of receiver
having antenna gain of 0 [dBi] for right-handed circularly polarization.
In cases where the power of the receiving GPS signal is estimated in less than
–158.5 [dBW] measured by the receiving antenna having gain of 0 [dBi] for righthanded circularly polarization, the maximum received power of IMES signal
should be installed and configured in –150 [dBW] or less at the input terminal of
receiver having antenna gain of 0 [dBi] for right-handed circularly polarization.
A 1.3.1.1.2.3 Maximum signal power level at the transmitter output
Equivalent Isotropically Radiated Power (EIRP) should be installed and
configured in –94.35 [dBW] or less at the output of IMES signal transmitter.
A 1.3.1.1.3 PRN code
Same code sequence as PRN code of C/A signal of applicable document (1), see the
applicable document (1) from number 173 to 182.
NOTE: Those set of PRN code are NOT allowed to use outside of Japan currently.
A2
IS-QZSS Ver.1.6
A 1.3.1.1.4 Navigation message
Same word structure and modulation scheme of applicable document (1).
The bit rate is defined as the "High-Speed Bit Rate" (250 [bps]) and the "GPS Compatible Bit
Rate" (50 [bps]).
A 1.3.1.1.5 Carrier wave characteristics
A 1.3.1.1.5.1 Correlation loss
Correlation loss means the difference between the transmitted power and received
power by reverse diffusion. Correlation loss power level is 1.2 [dB] or less.
A 1.3.1.1.5.2 Carrier phase noise
Carrier phase noise of unmodulated carrier wave before PRN code and navigation
message are superposed should keep the level which PLL of 10 [Hz] one sideband
of PLL is able to phase tracking at 0.2 [rad] (RMS).
A 1.3.1.1.5.3 Spurious characteristics
Spurious power level is –40 [dB] or less to unmodulated carrier power level within
frequency band.
A 1.3.1.1.5.4 Polarization characteristics
This means the right-hand circularly polarized spread spectrum signal or the
linearly polarized spread spectrum signal. And axis ratio guarantees minimum
signal power level.
A 1.3.1.2 Message Characteristics
A 1.3.1.2.1 Word structure
One word is made up of 30 bits. Word counter is set for each word. Moreover, each word consists
of an 8 bits preamble or a 3 bits of word counter, data bits (16 bits or 21 bits) and 6 bits of parity
in the end.
A 1.3.1.2.1.1 Word counter
Each word has its "Word counter". This "Word counter" increments every word
transmission including the word that "Word counter" is not included.
Identifying the segment of word and frame is assisted with "Word counter". This 3
bits value skips instead of taking the same value as first 3 bits of preamble
("100"(B)) for the assist of identifying the segment.
An example of setting "Word counter" is shown in Figure 1.3.1-1.
A3
IS-QZSS Ver.1.6
1
Word count
0
0
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Pr e am ble
0
Data
1 0 0 1 1 1 1 0
Parity
CNT
0
0
1
Data
0 0 1
Parity
Pr e am ble
0
1
0
Data
1 0 0 1 1 1 1 0
Parity
CNT
0
1
1
0 1 1
Data
Parity
Data
Parity
CNT
1
0
1
1 0 1
Pr e am ble
1
1
0
Data
1 0 0 1 1 1 1 0
Parity
CNT
1
1
1
1 1 1
Data
Parity
Data
Parity
Data
Parity
CNT
0
0
0
0 0 0
CNT
0
0
1
0 0 1
Figure 1.3.1-1 An example of setting "Word counter"
A 1.3.1.2.1.2 Parity
The 6 bit parity code added to the end of 30 bit word is the same (32.26) Hamming
code as specified in 20.3.5.1 of applicable documents (1).
This parity assists identifying word segment.
(1) Parity Algorithm
The 6 bit parity code added to the end of 30 bit word is the same (32.26) Hamming
code as specified in 20.3.5.1 of applicable documents (1).
(2) Parity Check Algorithm
Same as the applicable document (1) in section 20.3.5.2.
A 1.3.1.2.2 Frame structure
One frame is made (consists) of multiple number of integer of one word and has following style
indicated on the figures shown in Figure 1.3.1-2. This figure indicates the example by 3
words/frame. In case of over 4 words/frame, 3 bits word counter is repeated after second word as
necessary times.
That is to say, first word comes with 8 bit preamble and 3 bits message type ID (MID) follows.
The others bits are all data bit except above 3 bits word counter and 6 bits parity.
A4
IS-QZSS Ver.1.6
Bits ->
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
In case of
1 word/frame
Preamble
MSG
Type ID
Data Bits
Parity
In case of
2 words/frame
Preamble
MSG
Type ID
Data Bits
Parity
COUNT
Data Bits
Parity
In case of
3 words/frame
Preamble
MSG
Type ID
Data Bits
Parity
COUNT
Data Bits
Parity
Figure 1.3.1-2 IMES L1C/A frame structure
A5
29
30
1
2
3
COUNT
4
5
6
7
8
9
10
11
12
13
14
15
Data Bits
16
17
18
19
20
21
22
23
24
25
26
27
28
Parity
29
30
IS-QZSS Ver.1.6
A 1.3.1.2.2.1 Preamble
The 8 bits preamble added to the beginning of the first word of each frame is 9E(H)
Identifying the each word and frame segment is assisted with this preamble.
This value allows the identification of IMES signal from GPS and QZSS, unlike
the applicable document (1) in section 20.3.3.1.
A 1.3.1.2.2.2 Message type ID (MID)
3 bits message type ID (MID) which is added to the preamble of the first word of
each frame indicates its frame length and contents.
Table 1.3.1-1 shows the MID value and its associated frame length, contents, and
Maximum Repetition Period (s).
The Maximum repetition Cycle is defined that absolute position information is
sent from the IMES transmitter at each cycle. Because of this, users could get not
only ID type message but also absolute position information without data server
for disaster-management in emergency situations.
Table 1.3.1-1 Definition of IMES L1C/A message type ID
MID
Frame
Length
(words)
Contents
Maximum Repetition
Period
(seconds)
(provisional)
12
0(="000"(B))
3
1(="001"(B))
4
Position 1 (Floor number, Latitude and
Longitude)
Position 2 (Floor number, Latitude,
Longitude, Height and IMES Accuracy
Index)
2(="010"(B))
–
Reserved
–
3(="011"(B))
1
Short ID
–
4(="100"(B))
2
Medium ID
–
5(="101"(B))
–
Reserved
–
6(="110"(B))
–
Reserved
–
7(="111"(B))
–
Reserved
–
A 1.3.1.2.3 Message contents
A 1.3.1.2.3.1 Message type ID "000" (B) position data 1 (Position 1)
When the Message type ID is "000"(B), the frame length is 3 words and its contents
indicates the position data 1 (Floor number, Latitude and Longitude). In addition,
these position data is "the position information on any location in the coverage of
the IMES transmitter", and may differ from "the position information on the
location the IMES transmitter itself installed". Position information of IMES
transmitter itself and transmitted position information and other information like
transmitting power are going to be registered with a database and maintained by
IMES Operating Supervisor to avoid misuse of IMES. On operation, this position
data will be consistent with the position data code using "Ucode" defined and
managed by Geographical Survey Institute of Japan with exchanging both
registered information mutually.
Frame structure is indicated on the Figure 1.3.1-3, refers to the Table 1.3.1-2 for
the Scale Factor (LSB) and numerical range.
A6
IS-QZSS Ver.1.6
word 1
2
3
4
5
6
7
Preamble, 8 bits
8
9
10
11
12
13
MSG
Type ID,
3 bits
14
15
16
17
18
19
20
21
Floor 8 bits
0 0 0
22
23
24
25
26
Lon LSB
3 bits
1
Lat LSB
2 bits
Bits ->
27
28
29
30
Parity
6 bits
word 2
CNT
3 bits
Latitude 21 bits (MSB)
Parity
6 bits
word 3
CNT
3 bits
Longitude 21 bits (MSB)
Parity
6 bits
Figure 1.3.1-3 IMES-L1C/A MID= "000"(B) « Position 1 » Frame Structure
Table 1.3.1-2 IMES-L1C/A MID= "000"(B) « Position 1 » Contents
Effective Range
#
Content
Bit
Length
Scale Factor
(LSB)
Minimum
-
Maximum
1
Floor
8
1
–50
-
204
2
Latitude
23*1
90./222
*2
deg.
24*1
180./222
*2
deg.
3 Longitude
Unit
FL
*1 Parameters so indicated shall be two's complement, with the sign bit (+ or –) occupying the MSB
*2 Effective range is the maximum range attainable with indicated bit allocation and scale factor.
(1) Floor number
The first word bit 12 to 19 indicated the floor number where the transmitter is
placed, and FL(th) is the unit.
Bits are unsigned 8 bit and Scale Factor is a floor. As it is indicated in the
equation below, –50 [FL] to +204 [FL] is the range of these bits by setting the
offset at –50 [FL]. In addition, "11111111"(B) [FL] means "outdoors".
FloorNumber = 2 FloorNumberBits − 50 [ FL]
(2) Latitude
The second word bit 4 as signed bit, bit 5 to 24 as MSB, and the bits 20 and 21
in the first word as LSB, are the latitude of transmitter and degree is the unit.
These total 23 bits are singed, Scale Factor is 90./222 [deg], and the range is –90
[deg] or more, but less than +90 [deg] with signed bit 2.
(3) Longitude
The third word bit 4 as signed bit, bit 5 to 24 as MSB, and the bits 22~24 in the
first word as LSB, are the longitude of transmitter and degree is the unit.
These total 24 bits are signed, Scale Factor is 180./223 [deg], and the range is
–180 [deg] or more, but less than +180 [deg] with signed bit2.
2
The two’s complement is used for expression of minus data.
A7
IS-QZSS Ver.1.6
A 1.3.1.2.3.2 Message type ID "001"(B) position data 2
When the Message type ID is "001"(B), this frame length is 4 words and its content
indicates the "position data 2" (Floor number, Latitude, Longitude, Height and
IMES Accuracy Index).
Frame structure is indicated on the Figure 1.3.1-4, and refers to the Table 1.3.1-3
for the Scale Factor (LSB) and range.
word 1
2
3
4
5
6
7
Preamble, 8 bits
8
9
10
11
12
13
MSG
Type ID,
3 bits
14
15
16
17
18
19
20
21
22
Floor 9 bits
0 0 1
23
24
25
26
Accuacy
Index 2 bits
1
Reserved
Bits ->
27
28
Latitude 21 bits (MSB)
Parity
6 bits
word 3
CNT
3 bits
Longitude 21 bits (MSB)
Parity
6 bits
word 4
CNT
3 bits
Lat LSB
3 bits
Lon LSB
4 bits
CNT
3 bits
Reserved
30
Parity
6 bits
word 2
Altitude 12 bits
29
Parity
6 bits
Figure 1.3.1-4 IMES-L1C/A MID="001" (B) « Position 2 » Frame Structure
Table 1.3.1-3 IMES-L1C/A MID="001" (B) « Position 2 » Contents
Effective Range
#
Content
Bit
Length
Scale Factor (LSB)
1
Floor
9
1
2
Latitude
24*1
90./223
*2
deg.
25*1
180./224
*2
deg.
3 Longitude
Minimum
-
Maximum
–50
-
204
Unit
FL
4
Altitude
12
1
–95
-
4000
M
5
Accuracy
Index
2
Enumerated Value
(Refer to Table 1.3.1-4)
0
-
3
-
*1 Parameters so indicated shall be two's complement, with the sign bit (+ or –) occupying the MSB
*2 Effective range is the maximum range attainable with indicated bit allocation and scale factor.
(1) Floor number
The first word bit 12 to 20 indicated the floor number where the transmitter is
placed, and FL(th) is the unit.
Bits are unsigned 9 bits and LSB is 0.5 floor. As it is indicated in the equation
below, –50 [FL] to +205 [FL] is the range of these bits by setting the offset at –50
[FL]. In addition, "11111111"(B) [FL] means "outdoors".
FloorNumber = 0.5 × 2 FloorNumberBits − 50[ FL]
A8
IS-QZSS Ver.1.6
(2) Latitude
The second word bit 4 as signed bit, bit 5 to 24 as MSB, and the bits 18~20 in the
fourth word as LSB, are the latitude of transmitter and degree is the unit.
These total 24 bits are signed, Scale Factor is 90./223 [deg], and the range is –90
[deg] or more, but less than +90 [deg] with signed bit2.
(3) Longitude
The third word bit 4 as signed bit, bit 5 to 24 as MSB, and the bits 21~24 in the
fourth word as LSB, are the longitude of transmitter and degree is the unit.
These total 25 bits are signed, Scale Factor is 180./224 [deg], and the range is
–180 [deg] or more, but less than +180 [deg] with signed bit2.
(4) Altitude
Fourth word bits 4 to 15 are the altitude of transmitter, and m (meter) is the unit.
These total 12 bits are unsigned, and as it is indicated in the equation below, it
indicates the value in the range from –94 [m] to +4000 [m] by setting the offset
at –95 [m]. In addition, Altitude="000000000000"(B) means that effective altitude
information is not set up (No Altitude information).
Altitude = 2 AltitudeBits − 95[m]
(5) IMES Accuracy Index
An "IMES accuracy index" shows the approximate range which can receive the
message from transmitter (i.e., receivable range). We assume that it would be
used by receivers to estimate the maximum error in the received position
information.
The first word bits 23 to 24 are the accuracy (error) indicator of the position data
expected when a user received the signal from the transmitter with Received
Power Level=–160 [dBW] (EIRP). The value of an IMES accuracy index takes the
integral range from 0 to 3. You can see the relationship between the IMES
Accuracy Index and the IMES Accuracy in Table 1.3.1-4.
Table 1.3.1-4 The relationship between the IMES Accuracy Index and IMES Accuracy
IMES Accuracy Index (N)
0 (="00"(B))
IMES Accuracy [m]
Indefinable:
1 (="01"(B))
IMES Accuracy
<
< 15.0 (T.B.D.)
2 (="10"(B))
7.0 (T.B.D.) ≤
IMES Accuracy
3 (="11"(B))
15.0 (T.B.D.) ≤
IMES Accuracy
7.0 (T.B.D.)
The IMES Accuracy is calculated by the following equation. According to the
above table, the value of the IMES accuracy index corresponding to a result is
stored in an applicable bit.
A9
IS-QZSS Ver.1.6
Pt − Pr
 λ
r = 
×10 20
4
π

where
r:
λ:
Ht:
Hr:
Pt:
Pr:
2

 − (H t − H r )2


IMES Accuracy [m] (Receivable distance)
Wavelength of the transmitted signal (about 0.19 [m])
Height of the antenna of the transmitter [m]
Height of the antenna of the receiver (=1 [m])
Transmitting Power Level (EIRP) [dBW]
Receiving Power Level (EIRP) (=–160 [dBW])
You can see an example of calculation result of the accuracy by this equation is
shown in Figure 1.3.1-5.
Transmitting Power Level (EIRP)
[dBW]
2.5
-94.4
-95.0
-96.0
-97.0
-98.0
-99.0
-100.0
-101.0
-102.0
-103.0
-104.0
-105.0
-106.0
-107.0
-108.0
-109.0
-110.0
-111.0
-112.0
-113.0
-114.0
13
12
11
9
8
7
7
6
5
5
4
3
3
3
3.0
3.5
19
17
15
13
12
11
9
8
7
6
6
5
4
4
3
3
2
24
21
19
17
15
13
12
10
9
8
7
6
5
5
4
3
3
2
2
4.0
29
27
24
21
19
17
15
13
12
10
9
8
7
6
5
4
4
3
2
4.5
29
27
24
21
19
17
15
13
12
10
9
8
7
6
5
4
3
2
Height of the antenna of the transmitter [m]
5.0
6.0
7.0
8.0
9.0 10.0 12.0
29
29
28
28
28
28
27
27
26
26
26
26
25
25
24
23
23
23
23
22
21
21
21
21
20
20
19
18
19
18
18
18
17
17
16
15
14
13
17
16
16
15
13
13
12
10
15
14
14
13
12
12
11
10
8
13
11
11
10
10
9
8
7
6
10
9
9
8
5
9
8
7
7
7
6
5
8
6
6
5
5
5
5
3
4
3
14.0
26
24
20
17
14
11
16.0
25
22
19
15
12
18.0
24
21
17
13
20.0
22
19
15
Figure 1.3.1-5 An example of calculation result of the IMES accuracy
(The round mark of green, yellow, and red corresponds to 0, 1 and 2 of an IMES accuracy index,
respectively)
In a receiver, it is desirable to compute more exact accuracy information from
this accuracy index and received power level (the difference from –160 [dBW]).
A 1.3.1.2.3.3 Message type ID "011"(B) short ID
In the event that Message type ID is "011"(B), this frame length is 1 word and its
contents is short ID (IDS).
Figure 1.3.1-6 shows the frame structure and IDS of 12 bit and Boundary Detection
(BD) flag of 1 bit are transmitted.
word 1
1
2
3
4
5
6
7
Preamble, 8 bits
8
9
10
11
12
13
14
MSG
Type ID,
3 bits
15
16
17
18
19
20
Short ID (IDS)
12 bits
0 1 1
21
22
23
24
BD 1bit
Bits ->
25
26
27
28
Parity
6 bits
Figure 1.3.1-6 IMES-L1C/A MID="011"(B) « Short ID » Frame Structure
A10
29
30
IS-QZSS Ver.1.6
(1) Short ID
The first word bits 12 to 23 are the IDS. Users can define the contents freely by
themselves.
IDS="111111100000"(B) ~ "111111111111"(B) is the bit pattern reserved for some
specific purposes, for instance, emergency message when disaster occurs, should
not be defined by users and not be used in general.
(2) Boundary Detection flag
The first word bit 24 is the BD flag. BD flag="1" means that the receiving
environment has both signals from GPS satellites and IMES transmitters. The
flag helps recognition of deep indoor or near outside where receiver can acquire
GPS signals. The usage of the flag which we assume is as follows:
- When moving to the outdoors from indoor, if this flag becomes "1", an IMES
receiver would start to search the GPS signals.
- When moving indoors from the outdoors conversely, if this flag becomes "0", the
receiver would be kept from searching GPS signals.
A 1.3.1.2.3.4 Message type ID "100"(B) Medium ID
In the event that Message type ID is "100"(B), this frame length is 2 words and its
contents is medium ID (IDM).
Figure 1.3.1-7 shows the frame structure and IDM (length=33 bits) and BD flag (1
bit) are transmitted.
word 1
1
2
3
4
5
6
7
8
Preamble, 8 bits
9
10
11
12
13
14
MSG
Type ID,
3 bits
CNT
3 bits
16
17
18
19
20
Medium ID (IDM)
MSB 12 bits
1 0 0
word 2
15
Medium ID (IDM)
LSB 21 bits
21
22
23
24
BD 1bit
Bits ->
25
26
27
28
29
30
Parity
6 bits
Parity
6 bits
Figure 1.3.1-7 IMES-L1C/A MID="100"(B) « Medium ID » Frame Structure
(1) Medium ID
The first word bit 12 to 23 as MSB, and the bits 4~24 in the second word as LSB,
are the IDM (total: 33 bits). Users can define the contents freely by themselves.
(2) Boundary Detection flag
The first word bit 24 is the BD flag. For more information, please refer to Section
A 1.3.1.2.3.3(2).
A 1.3.2 IMES-L1C type-signal specification
TBD
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IS-QZSS Ver.1.6
A 1.4 Installation of transmitter
This chapter is scheduled to explain the transmitter installation such as the example of
separation distance between transmitter and receiver as below, as well as the interval
between transmitters, and how to choose the PRN number for each transmitter, etc.
A 1.4.1 Examples of separation distance from transmitter to receiver
Examples of separation distance and transmitter EIRP in accordance with maximum
receiving power limit of IMES signal L1C/A type is shown in Figure 1.4.1-1.
EIRP of an IMES transmitter should not exceed
beyond the maximum power level -94.35[dBW].
-94.35[dBW]
-104.1[dBW]
3[m]
3[m]
-94.35[dBW]
-140.25[dBW]
5[m]
5[m]
-99.6[dBW]
-144.7[dBW]
-150.0[dBW]
-150.0[dBW]
GPS receiving power level≧-158.5 [dBW]
GPS receiving power level＜-158.5 [dBW]
IMES receiving power level ＜-140 [dBW]
IMES receiving power level ＜-150 [dBW]
Figure 1.4.1-1 Examples of separation distance and transmitter EIRP in accordance with maximum
receiving power limit of IMES signal
A 1.5 Operation concept
For the information of Operation concept, please refer to Section A 1.2 Referenced
document (1).
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