Signal Deformation Proposal
R. Eric Phelts, Gabriel Wong, Todd Walter, Per Enge
Stanford University
IWG 26
February 5-7, 2014
Potential L1/L5 Tracking
Constraints
• Current constraints allow early minus late
(E-L) and double delta (DD) receivers
– each have three regions describing receiver
filter bandwidth, group-delay variation across
the passband, and correlator spacing
– SBAS GEOs have two regions
• Propose removing double delta altogether
and shrinking allowed region
– Also align SBAS & GPS tracking regions
– BOC regions still being investigated
2
Current Allowed L1 Receiver Constraints
Nominal SD Range Error Contours for WAAS Users
24
0.6
2
0.2
0.7
0.3
0.4
0.5
0.6
0.1
0.5
4
0.6
6
0.4
8
1
0.
0.6
10
0.
6
0.7
0.5
0.3
0.1
14
12
0.6
0.6
0.2
0.6
Current
Reference
16
0.6
MAX: 0.884m; MIN: 0.0455m
0.7
0.8
0.6
0.7
0.7
0.7
0.6
0.2
0.3
0.4
0.6
0.6
0.6
0.1
0.2
0.6
0.4
0.1
(MHz)
User Receiver
Double-SidedBandwidth
Air BW (MHz)
0.6
0.5
0.3
20
18
0.6
0.6
New
New
Reference
Reference
22
0.5
0.6
0.7
0.8
Air Correlator Spacing (chips)
0.9
1
UserReceiver
ReceiverCorrelator
CorrelatorSpacing
Spacing(chips)
(chips)
User
1.1
3
Nominal Signal Deformations on
L1 and L5
Blk-IIF-SVN62-L5 (5-chips) vs All SVN
1.4
Normalized Step Response
1.2
1
Different code
modulations have
similar structures at
chip transitions.
0.8
0.6
0.4
All SVN
Blk IIF-SVN62-L5-I
Blk IIF-SVN62-L5-Q
0.2
0
0
0.1
0.2
0.3
Time [sec]
0.4
0.5
0.6
4
Slide Courtesy: Gabriel Wong
New Proposed Allowed DF Receiver
Constraints (L1, L5)
Nominal SD Range Error Contours for WAAS Users
24
2
0.6
0.7
0.8
0.6
0.7
0.7
0.7
0.6
0.2
0.3
0.4
0.6
0.6
0.6
0.7
0.3
0.4
0.5
0.6
0.1
0.6
0.1
0.2
0.2
0.5
4
0.6
6
0.4
8
1
0.
0.6
10
0.
6
0.7
0.5
0.3
0.1
14
12
0.6
0.6
0.2
(MHz)
User Receiver
Double-SidedBandwidth
Air BW (MHz)
MAX: 0.884m; MIN: 0.0455m
0.6
0.6
0.4
0.1
16
0.6
0.6
0.6
20
18
L5
L1
0.5
0.3
22
0.5
0.6
0.7
0.8
Air Correlator Spacing (chips)
0.9
1
UserReceiver
ReceiverCorrelator
CorrelatorSpacing
Spacing(chips)
(chips)
User
1.1
5
Proposal for BPSK Signals
• Only allow early minus late
• L1 C/A
– Bandwidth between 12 and 24 MHz
– Correlator spacing between 0.08 and 0.12
– Group delay < 150 nsec (including antenna)
• L5/E5A
– Bandwidth = tight region around 24 MHz
– Correlator spacing = tight region around 1 chip
• Exact region TBD
– Group delay < 150 nsec (including antenna)
6
Proposal for SBAS Satellites
• Wide bandwidth SBAS satellites shall be
treated identically to the BPSK
requirements for GPS
• Narrow bandwidth SBAS satellites require
one of the following actions:
– Narrow bandwidth SBAS satellites not
allowed
– Bandwidth is indicated in message
• Tracked differently, may not be used for vertical
– Still tracked with narrow correlator, but UDRE 7
Example:
Digital Signal Deformation Fault on
CBOC(1,1) or TMBOC(1,1)
1
Some modernized
code correlation peaks
are relatively complex
0.5
0
-0.5
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
Code Offset (chips)
0.4
0.6
0.8
1
8
Proposal for BOC Signals
• EUROCAE WG-62 proposed not using
BOC(6,1) component
– Agree to only track BOC(1,1)
• Same filter region as for L1 BPSK
– Bandwidth between 16 and 24 MHz
– Group delay < 150 nsec (including antenna)
– Correlator spacing still under evaluation
• Early minus late only
9
Backup Slides
10
Nominal L1 SD Range Errors for Allowed
User Receiver Configurations
24
2
0.6
0.3
0.4
0.5
0.6
0.1
0.6
0.7
0.7
0.8
0.6
Propose removal
0.6
0.1
0.2
0.2
0.7
0.7
0.7
0.6
0.2
0.3
0.4
0.6
0.6
0.5
4
0.6
6
0.4
8
1
0.
0.6
10
0.
6
0.7
0.5
0.3
0.1
14
12
0.6
0.6
0.2
16
MAX: 0.884m; MIN: 0.0455m
0.6
0.6
0.4
0.1
Double-SidedBandwidth
Air BW (MHz)
(MHz)
User Receiver
20
18
0.6
0.6
0.6
0.5
0.3
22
0.5
0.6
0.7
0.8
Air Correlator Spacing (chips)
0.9
1
User Receiver Correlator Spacing (chips)
1.1
11
0.1
0.14
0.12
0.2
0.3
4
0
.
0
0.4
0.5
0.6
0.7
0.8
0.02
0.1
0.08
0.06
0.04
0.02
0.
0
0.0 4
0. 6
08
0.08
0.0
6
0.1
0.
12
0.14
.12
14 0
0.1
0.08
0.06
12
0.1
0.1
4
0.1
6
16
0.02
18
0.06
0.04
MAX: 0.209m; MIN: 0.0095m
0.04
Bandwidth (MHz)
20
0.046
0.0
18
0.02
220.
0.04
0.06
0.08
0.2
0.
16
24
0.02
L5 Nominal Deformation Errors
(Updated)
0.9
Correlator Spacing (chips)
1
1.1