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DISTRIBUTION STATEMENT A APPROVED FOR ... - GPS.gov

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50 APPENDIX 5: ANTI-SPOOFING STATUS FILE<br />

Appendix 5 describes the Anti-Spoofing statusStatus message format.<br />

50.1 Anti-Spoofing Status<br />

The Anti-Spoofing (A-S) Sstatus informs Users whether the Anti-Spoofing mode of each<br />

<strong>GPS</strong> SV is ON or OFF. There are two A-S statusStatus files named as.txt and as2.txt.<br />

The message files are simple text files that identify each satellite in the <strong>GPS</strong><br />

constellation by a two digit PRN number and a three digit SVN number and it shows the<br />

SV’s A-S statusStatus (ON/OFF). The difference between the two A-S statusStatus<br />

files is the PRN Numbers. As.txt addresses PRNs 1-32 and as2.txt addresses PRNs<br />

33-63. An example of the A-S statusStatus (as.txt) is shown in Figure 50-1.<br />

Anti Spoofing (A-S) Status<br />

PRN SVN A-S<br />

1 049 ON<br />

2 061 ON<br />

3 033 ON<br />

4 034 ON<br />

5 050 ON<br />

6 036 ON<br />

7 048 ON<br />

8 038 ON<br />

9 039 ON<br />

10 040 ON<br />

11 046 ON<br />

12 058 ON<br />

13 043 ON<br />

14 041 ON<br />

15 055 ON<br />

16 056 ON<br />

17 053 ON<br />

18 054 ON<br />

19 059 ON<br />

20 051 ON<br />

21 045 ON<br />

22 047 ON<br />

23 060 ON<br />

24 024 ON<br />

25 025 ON<br />

26 026 ON<br />

27 027 ON<br />

28 044 ON<br />

29 057 ON<br />

30 030 ON<br />

31 052 ON<br />

32 023 ON<br />

Figure 50-1 Sample of the Anti-Spoofing Sstatus file (as.txt)<br />

50-1<br />

ICD-<strong>GPS</strong>-870<br />

23 June 2011

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