
Serial Port Output
91
Serial Port Output
satellite for which the receiver has collected almanac data. Table 4.10 below
outlines the contents of the SALM message.
The structure of the SALM message is shown below:
$PASHR,ALM,<Almanac Data + Checksum>
Table 4.10.
ALM Message Structure
Type
Size
Contents
short
2
Satellite PRN -1
short
2
Health. see ICD - 200 for description
float
4
e. Eccentricity
long
4
toe. Reference time for orbit (sec)
float
4
I0. Inclination angle at reference time (semi-circles).
float
4
OMEGADOT. Rate of right Asc. (semi-circles per sec).
double
8
(A)1/2. Square root of semi-major axis (meters 1/2).
double
8
(OMEGA)0. Lon of Asc. node (semi-circles).
double
8
ω
. Argument of Perigee (semi-circles)
double
8
M0. Mean anomaly at reference time (semi-circle).
float
4
af0. sec
float
4
af1. sec/sec.
short
2
almanac week number
short
2
GPS week number
long
4
Seconds of GPS week
unsigned short
2
Word checksum
Total bytes70