Specifications

Command/Response Formats 153
Commands
Example: Send GDC message to the current port.
$PASHQ,GDC <enter>
$PASHR,GDC
This message outputs the current position in the Grid Coordinate system selected by
the user.
The response message is in the form:
$PASHR,GDC,m1,s2,f3,f4,d5,d6,f7,f8,M,f9,M,d10,s11,s12*cc <enter>
The altitude is either ellipsoidal (default) or geoidal (mean-sea-level) depending on the selection
made with $PASHS,HGT. The Geoidal separation when subtracted from the ellipsoidal altitude
gives the geoidal altitude.
Table 6.83: GDC Message Structure
Parameters Description Range
m1 UTC of position in hours, minutes, and decimal seconds (hhmmss.ss) 0—235959.90
s2 Map projection type EMER/TM83/
OM83/LC83/
STER/LC27/
TM27/TMA7
f3 x (Easting) User Grid coordinate (meters) ±9999999.999
f4 y (Northing) User Grid coordinate (meters) ±9999999.999
d5 Position Indicator
1: Raw Position
2: RTCM differential, or CPD float position
3: Carrier Phase differential (CPD) fixed
1, 2, 3
d6 Number of GPS satellites being used 3 - 12
f7 Horizontal Dilution of Position (HDOP) 999.9
f8 Altitude in meters ±99999.999
M Altitude units (M=meters) M
f9 Geoidal separation in meters w.r.t. selected datum and Geoid Model ±999.999
M Geoidal separation units (M-meters) M
d10 Age of differential corrections 0-999
s11 Differential reference station ID 0-1023
s12 Datum type See Appendix A
cc checksum