Saw: sbas almanac data, Reminder on how to output sag messages – Spectra Precision ProMark 800 Reference Manual User Manual
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Output Message Library
Reminder on How
to Output SAG
Messages
Use the $PASHS,RAW command with the syntax below:
$PASHS,RAW,SAG,<port_ID>,ON,<Rate>
For more details on the $PASHS,RAW command, refer to the
Set Command Library Chapter.
As an example, the command below will output SAG
messages on port A at a rate of 15 seconds:
$PASHS,RAW,SAG,A,ON,15
SAW: SBAS Almanac Data
This message contains almanac data for one SBAS satellite.
The message is as follows:
$PASHR,SAW,<structure>
The message’s binary structure is described in the table
below.
Float
4
Reference time of longitude of first node
(seconds)
w
Float
4
Argument of perigee (semicircles)
Float
Af0
4
Correction to mean value (43200 s) of
Draconic period
Float
Af1
4
Af1=d(Af0)/dt(sec/sec)
Float
4
Satellite clock offset (seconds)
Unsigned short Checksum 2
The checksum is computed by breaking
the structure into 21 unsigned shorts, add-
ing them together, and taking the least sig-
nificant 16 bits of the result.
Total
44
Type
Name
Size
Contents
Type
Name
Size
Contents
char Id
1
Data
ID