EUROPEAN ORGANISATION FOR THE SAFETY OF
AIR NAVIGATION
EUROCONTROL
ASTERIX Part 15
Category 065
Appendix A
Coding rules for
"Reserved Expansion
Field"
Edition
Edition Date
Status
Class
:
:
:
:
1.1
November 2013
Released Issue
General Public
EUROPEAN AIR TRAFFIC MANAGEMENT
DOCUMENT IDENTIFICATION SHEET
DOCUMENT DESCRIPTION
Document Title
Coding rules for "Reserved Expansion Field"
EWP DELIVERABLE REFERENCE NUMBER
PROGRAMME REFERENCE INDEX
EDITION :
1.1
EDITION DATE :
November 2013
Abstract
Keywords
CONTACT PERSON :
A. Engel
TEL : +32-2-729 3355
DIVISION :
DSS/REG/SES
DOCUMENT STATUS AND TYPE
STATUS
Working Draft
Draft
Proposed Issue
Released Issue
CATEGORY
Executive Task
Specialist Task
Lower Layer Task
CLASSIFICATION
General Public
EATCHIP
Restricted
ELECTRONIC BACKUP
INTERNAL REFERENCE NAME :
HOST SYSTEM
MEDIA
Microsoft Windows
Type : Hard disk
Media Identification :
Edition : 1.1
Released Issue
SOFTWARE(S)
Page 2
DOCUMENT APPROVAL
The following table identifies all management authorities who have successively approved the
present issue of this document.
AUTHORITY
NAME AND SIGNATURE
DATE
ASTERIX
Manager
A. Engel
SES Unit
Manager
P. Green
DSS
Director
L. Tytgat
On behalf of the Director
General
by special delegation
B. Redeborn
Principal Director ATM
Edition : 1.1
Released Issue
Page iii
DOCUMENT CHANGE RECORD
The following table records the complete history of the successive editions of the present
document.
EDITION
DATE
1.0
April 2010
Creation
1.1
November
2013
Data Item “Record Length” added
Edition : 1.1
REASON FOR CHANGE
Released Issue
SECTIONS
PAGES
AFFECTED
All
Page iv
TABLE OF CONTENTS
DOCUMENT IDENTIFICATION SHEET................................................................................. ii
DOCUMENT APPROVAL ..................................................................................................... iii
DOCUMENT CHANGE RECORD ......................................................................................... iv
TABLE OF CONTENTS ......................................................................................................... v
EXECUTIVE SUMMARY........................................................................................................ 1
1. INTRODUCTION ....................................................................................................2
1.1
Scope ............................................................................................................................................................ 2
1.2
Encoding Rule ............................................................................................................................................. 2
2. DESCRIPTION OF THE CONTENT OF RESERVED EXPANSION FIELD ...........3
2.1
Length Indicator ......................................................................................................................................... 3
2.2
Items indicator ............................................................................................................................................ 4
2.3
Position of the System Reference Point ..................................................................................................... 5
2.4
ASTERIX Record Lenth ............................................................................................................................ 6
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Released Issue
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EXECUTIVE SUMMARY
The Reserved Expansion Field contains the ASTERIX Record length.
The Reserved Expansion Field of category 065 enables an SDPS to communicate its system
reference point (WGS-84) to subsequent systems.
Edition : 1.1
Released Issue
Page 1
1. INTRODUCTION
1.1 Scope
This document describes the way to encode information in the Reserved
Expansion Field of SDPS Service Status Messages from ASTERIX Cat 065.
1.2 Encoding Rule
The Reserved Expansion Field shall be present in each ASTERIX message as
it contains information on the ASTERIX Record Length.
Edition : 1.1
Released Issue
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2.
DESCRIPTION OF THE CONTENT OF RESERVED EXPANSION
FIELD
2.1 Length Indicator
Definition :
Format :
Structure:
This field indicates the total length in octets of the Reserved
Expansion Field (including the REF length itself)
One-octet fixed length Data Item
Octet no. 1
8
7
6
5
4
3
2
1
LEN
bits 8-1
(LEN)
Length of REF in octets,
including the Length Indicator
itself.
Encoding Rule :
This item shall be present in every REF
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Released Issue
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2.2 Items indicator
Definition :
Format :
Structure:
This field indicates what are the items encoded in the REF
One-octet fixed length Data Item
Octet no. 1
8
7
6
5
4
3
2
1
SRP ARL
0
0
0
0
0
0
bits 8
(SRP)
=0
=1
bits 7
(ARL)
=0
=1
bits 6/1
“System Reference Point” data
item is not present in the REF
“System Reference Point” data
item is present in the REF
“ASTERIX Record Length” data
item is not present in the REF
“System Reference Point” data
item is present in the REF
Spare bits set to 0
Encoding Rule : This item shall be present in every REF
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Released Issue
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2.3 Position of the System Reference Point
Definition :
Format :
Structure:
Position of the system reference point in WGS-84 Coordinates.
Eight-octet fixed length Data Item
Octet no. 1
Octet no. 2
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
Latitude in WGS - 84
Octet no. 3
Octet no. 4
48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33
LSB
Octet no. 5
Octet no. 6
32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17
Longitude in WGS - 84
Octet no. 7
16 15 14 13 12 11 10
Octet no. 8
9
8
7
6
5
4
3
2
1
LSB
bits-64/33
(Latitude)
(LSB)
bits-32/1
In WGS-84 in two’s complement.
Range -90 <= latitude <= 90 deg.
= 180/230 degrees
(Longitude)
In WGS-84 in two’s complement.
Range -180 <= longitude < 180 deg.
(LSB)
= 180/230 degrees
The LSB provides a resolution better than 0.02m.
Encoding Rule:This item is optional
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2.4
ASTERIX Record Lenth
Definition :
Format :
Structure:
Length of the ASTERIX record in octets.
Two-octet fixed length Data Item.
Octet no. 1
16 15 14 13 12 11 10
Octet no. 2
9
8
7
6
5
4
3
2
1
ARL
bits-16/1
(ARL)
ASTERIX Record Length
Max. value = 65532
Note: The maximum value allowed in this data item has to be restricted to
65532 octets since the maximum length of an ASTERIX block is 65535
octets which includes a 1 octet field for the category number and 2 octets
for the block length.
Encoding Rule: This data item shall be present in every ASTERIX record.
Edition : 1.1
Released Issue
Page 6