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50 APPENDIX 5: ANTI-SPOOFING STATUS FILE<br />
Appendix 5 describes the Anti-Spoofing Status message format.<br />
50.1 Anti-Spoofing Status<br />
The Anti-Spoofing (A-S) Status informs Users whether the Anti-Spoofing mode of each<br />
<strong>GPS</strong> SV is ON or OFF. There are two A-S Status files named as.txt and as2.txt. The<br />
message files are simple text files that identify each satellite in the <strong>GPS</strong> constellation by<br />
a two digit PRN number and a three digit SVN number and it shows the SV’s A-S Status<br />
(ON/OFF). The difference between the two A-S Status files is the PRN Numbers.<br />
As.txt addresses PRNs 1-32 and as2.txt addresses PRNs 01-63. For the as2.txt file,<br />
the two digit PRN number and the three digit SVN field are zero padded. An example of<br />
the A-S Status (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 Status file (as.txt)<br />
50-1<br />
<strong>ICD</strong>-<strong>GPS</strong>-<strong>870</strong><br />
15 June 2011
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