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Table 6.45 outlines the GGA structure.
Field
m1
m2
c1
m3
c2
d1
d2
f1
f2
M
f3
M
f4
d3
*cc
If there is no valid position, GGA still provides: time, position flag, number of
satellites, HDOP, age of corrections, and base station ID
If there are not enough satellites to compute HDOP, then the HDOP field is null. If
the receiver is not in Differential or RTK mode, then the age of corrections, base
station ID fields are null.
When running in the 5 Hz option, the GG Surveyor limits the number of available used satellites to
16.
Command/Response Formats
Table 6.45: GGA Structure
Description
Current UTC time of position fix in hours, minutes and seconds
(hhmmss.ss).
Latitude component of position in degrees, minutes and fraction
of minutes (ddmm.mmmmmm).
Latitude sector, N = North, S = South.
Longitude component of position in degrees, minutes and
fraction of minutes (dddmm.mmmmmm).
Longitude sector, E = East, W = West.
Position Type, n
1 = Autonomous position
2 = position differentially corrected
3 = RTK float
4 = RTK fixed
number of GPS satellites used in position computation.
HDOP - horizontal dilution of precision
Altitude in meters above the geoid. For 2-D position
computation this item contains the altitude held fixed.
Altitude units, M = meters.
Geoidal separation (value output only if Geoidal Height option
(G) is installed in the receiver).
Geoidal separation units, M = meters.
Age of the differential corrections, sss, in seconds.
Base station ID (RTCM only)
checksum
Range
00 to 235959.50
0 to 90°
'N' or 'S'
0 to 180°
'E' or 'W'
1, 2, 3, 4
3 to 24
0 to 99.9
0 to 30000.000
'M'
±999.999
'M'
±999.999
0 to 1023
135
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