ashtech HDS800, Справочное руководство

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601
Data Output
SAL: GPS Almanac Data
This message contains almanac data for one GPS satellite.
The message is as follows:
$PASHR,SAL,<structure>
The message’s binary structure is described in the table
below.
Reminder on How
to Output SAL
Messages
Use the $PASHS,RAW command with the syntax below:
$PASHS,RAW,SAL,<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 SAL
messages on port A at a rate of 15 seconds:
$PASHS,RAW,SAL,A,ON,15
Type Name Size Contents
Short prn 2 Satellite PRN number minus 1 (0-31)
Short health 2 Satellite health
Float e 4 Eccentricity
Long toe 4 Reference time for orbit (sec)
Float i0 4
Inclination angle at reference time (semi-cir-
cles)
Float w dot 4 Rate of right ascension (semi-circles/sec)
Double A1/2 8 Square root of semi-major axis (meters1/2)
Double w0 8 Longitude of ascending node (semicircles)
Double w 8 Argument of perigee (semicircles)
Double M0 8 Mean anomaly at reference time (semi-circle)
Float Af0 4 Clock correction (sec)
Float Af1 4 Clock correction (sec/sec)
Short wna 2 Almanac week number
Short wn 2 GPS week number
Long 4 Seconds of GPS week
Unsigned
short Check-
sum
2
The checksum is computed by breaking the
structure into 34 unsigned shorts, adding them
together, and taking the least significant 16 bits
of the result.
Total 70