ashtech DG16 Reference Manual page 235

$PASHQ,SAL,[c1]
This command queries for satellite almanac data. c1 is the optional port designator
for the response. If a port is not specified, the receiver sends the response to the
current port.
$PASHR,SAL
This message is not output until the DG16 has completed downloading the current
GPS almanac file. The receiver begins downloading the almanac file automatically
almanac file can be obtained directly from the satellites, which happens
automatically and takes about twelve minutes, or, with the aid of software, a current
almanac file from another receiver can be manually downloaded into the DG16. A
separate almanac message is output for each satellite being tracked. The SAL
message contains information on satellite health, the almanac week number, and
a variety of orbital measurements. The response is output in the format:
$PASHR,SAL,<Satellite almanac data string + checksum>
Table 7.18 outlines the data string format.
Field
short prn
short health
float e
long toa
float i0
float omegadot
double roota
double omega0
double omega
double m0
float af0
float af1
short wna
short wn
long tow
Raw Data Commands
Table 7.18. $PASHR,SAL Data String
Bytes
2 Satellite PRN number -1
2 Satellite health
4 Eccentricity
4 Reference time for orbit (sec)
4 Inclination angle (semicircles)
4 Rate of right ascension (semicircles/sec)
8 Square root of semi-major axis (meters 1/2)
8 Longitude of ascending node (semicircles)
8 Argument of perigee (semicircles)
8 Mean anomaly at reference time (semicircles)
4 Clock correction (sec)
4 Clock correction (sec/sec)
2 Almanac week number
2 Week number
4 Seconds of GPS week
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