Spectra Precision ProMark 800 Reference Manual - Manual (Page 408)

396
Output Message Library
$PASHR,SBA,DAT,d1,m2,d3,d4,s5*cc
Where:
SAL: GPS Almanac Data
This message contains almanac data for one GPS satellite.
The message is as follows:
$PASHR,SAL,<structure>
The message’s binary structure is described in the table
below.
Parameter Description Range
d1 SBAS SV ID number 33-51
m2
Time tag: hhmmss.hh
The SBA,DAT message contains the time tag of
the beginning of WAAS message transmission
(WAAS message transmission time is 1 second)
000000.00-
235959.99
d3 RTCA message ID 0-63
d4
Error flags (in HEX): bit0-preamble error, bit1-par-
ity error
0-2
s5
RTCA message: 250 bit in 63 HEX numbers. The
data lie from left to right and from high-order to
low-order bits. The two low-order bits in the 63rd
number are not used.
*cc
Checksum, computed by “exclusive-ORing” all of
the bytes in the message between, but not includ-
ing, the “$” and the “*”. The result is “*cc” where c
is a hexadecimal character.
*00-*FF
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)