ashtech G12 - Page 173

159
Commands
$PASHQ,GST,[c1]
This command allows you to query for the GST message, where c1 is the optional
port designator for the output of the response. If a port is not specified, the receiver
sends the response to the current port.
$GPGST
The GST message contains UTC time, the RMS value of the standard deviation for
satellite range measurements, and the corresponding standard deviation values for
latitude, longitude, and altitude. The response is output in the format:
$GPGST,m1,f2,f3,f4,f5,f7,f8,f9*hh
Table 4.84 defines the message format.
Typical GST message:
$GPGST,130927.00,18.45,,,,17.78,11.74,28.68*71
Table 4.84. $GPGST Message Format
Parameter Description Range
m1 UTC time (hhmmss.ss) of the position fix 000000.00 to
235959.95
f2 RMS value of the standard deviation of the satellite range inputs to
the navigation processor. This field is related to remaining fields as
follows:
• (RMS value of standard deviation range inputs)
2
* (HDOP)
2
=
(Standard deviation of latitude error)
2
+ (Standard deviation of
longitude error)
2
• (RMS value of standard deviation of range inputs)
2
* (VDOP)
2
=
(Standard deviation of altitude error)
2
0.00 - 99.99
f3 Standard deviation of semi-major axis of error ellipse (meters).
THIS FIELD NOT IMPLEMENTED
N/A
f4 Standard deviation of semi-minor axis of error ellipse (meters).
THIS FIELD NOT IMPLEMENTED
N/A
f5 Orientation of semi-major axis of error ellipse (degrees from true
north). THIS FIELD NOT IMPLEMENTED
N/A
f6 Standard deviation of latitude error (meters) 0.00 - 99.99
f7 Standard deviation of longitude error (meters) 0.00 - 99.99
f8 Standard deviation of altitude error (meters) 0.00 - 99.99
*hh Checksum 2-character hex
G12RevD.book Page 159 Tuesday, April 2, 2002 4:33 PM