Topcon GB-500, Operator'S Manual

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NMEA Standards
Topcon GB-500 Operator’s Manual
D-4
• The transmission identifier of the GGA message is always
set to GP, regardless of whether positioning is calculated
with GPS only, GLONASS only, or a combination of GPS
and GLONASS.
• When the GB-500 uses GPS+GLONASS data for RTK and
DGPS positioning, the age of differential GPS data and the
differential reference station ID will be shown regarding the
GPS data.
In contrast, when the GB-500 uses GLONASS data only,
the age of differential GPS data and the differential
reference station ID will be shown regarding the
GLONASS data.
6 GPS quality indicator
0: Fix not available or invalid.
1: GPS SPS Mode (single point mode), fix valid
2: Differential GPS SPS Mode, fix valid
3: GPS PPS Mode (single point mode), fix valid
4: RTK Fix solution
5: RTK Float solution
6: Estimated (dead reckoning) mode
7: Manual input mode
8: Simulator mode
7 Number of satellites used for position computation
8 Horizontal dilution of precision (HDOP) [-]
9 Altitude above geoid in selected datum [meters]
10 Symbol “M” (denotes that altitude is in meters)
11 Geoidal separation: the difference between the earth ellipsoid and
geoid defined by the reference datum [meters]
12 Symbol “M” (denotes that geoidal separation is in meters)
13 Age of differential GPS data [seconds]
14 Differential reference station ID (an integer between 0000 and 1023)
15 Checksum
Table D-2. GGA Message Ouputs (Continued)
Field Description