ashtech GG Surveyor Reference Manual page 157

Range residuals are recomputed after the GGA position is computed. Therefore the mode m is
always 1. There will be a range residual sxx.x for each satellite used in position computation, where
range residuals for GPS satellites are included in the GPGRS message, and range residuals for
GLONASS satellites are included in the GLGRS message.
Table 6.49 outlines the GRS message structure.
Field
m1
d1
f1
Example:
Query: $PASHQ,GRS,A or
Set: $PASHS,NME,GSN,A,ON
Response: $GPGRS,180257.50,1,+00.3,-00.4,+00.2,+00.5,+00.7,-00.8*64
Table 6.50 outlines a typical GPGRS response message. Table 6.51 outlines a typical
GLGRS response message.
Command/Response Formats
Table 6.49: GRS Structure
Current UTC time, (hhmmss.ss), of GGA position fix in hours, minutes, and seconds
hh = Hours (00 to 23)
mm = Minutes (00 to 59)
ss.ss = Seconds (00.00 to 59.99)
Mode, used to compute range residuals
0 - Residuals were used to calculate the position given in the matching GGA line
1 - residuals were recomputed after the GGA position was computed
Range residuals (sign s = + or -, and magnitude xx.x) for each satellite used in
position computation.
$GLGRS,180257.50,1,-00.2,+00.4,+00.3,-00.6,+00.5*38
Table 6.50: Typical GPGRS Response Message
Field
$GPGRS Header
180257.50 Time of position fix
1 Mode
+00.3 Range residual for first GPS satellite
-00.4 Range residual for second GPS satellite
+00.2 Range residual for third GPS satellite
+00.5 Range residual for fourth GPS satellite
Description
Significance
139