hi Guys,
A quick example on what $GPGGA messages are. Keep in mind that the sentence Identifier can also be displayed as $GNGGA. The message is the same but some GNSS receivers use this format.
| Name | Example Data | Description |
|---|---|---|
| Sentence Identifier | $GPGGA | Global Positioning System Fix Data |
| Time | 170834 | 17:08:34 Z |
| Latitude | 4124.8963, N | 41d 24.8963’ N or 41d 24’ 54" N |
| Longitude | 08151.6838, W | 81d 51.6838’ W or 81d 51’ 41" W |
| Fix Quality: 0 = Invalid 1 = GPS fix 2 = DGPS fix |
1 | Data is from a GPS fix |
| Number of Satellites | 05 | 5 Satellites are in view |
| Horizontal Dilution of Precision (HDOP) | 1.5 | Relative accuracy of horizontal position |
| Altitude | 280.2, M | 280.2 meters above mean sea level |
| Height of geoid above WGS84 ellipsoid | -34.0, M | -34.0 meters |
| Time since last DGPS update | blank | No last update |
| DGPS reference station id | blank | No station id |
| Checksum | *75 | Used by program to check for transmission errors |
Global Positioning System Fix Data. Time, position and fix related data for a GPS receiver.
eg2. $–GGA,hhmmss.ss,llll.ll,a,yyyyy.yy,a,x,xx,x.x,x.x,M,x.x,M,x.x,xxxx
hhmmss.ss = UTC of position
llll.ll = latitude of position
a = N or S
yyyyy.yy = Longitude of position
a = E or W
x = GPS Quality indicator (0=no fix, 1=GPS fix, 2=Dif. GPS fix)
xx = number of satellites in use
x.x = horizontal dilution of precision
x.x = Antenna altitude above mean-sea-level
M = units of antenna altitude, meters
x.x = Geoidal separation
M = units of geoidal separation, meters
x.x = Age of Differential GPS data (seconds)
xxxx = Differential reference station ID
eg3. $GPGGA,hhmmss.ss,llll.ll,a,yyyyy.yy,a,x,xx,x.x,x.x,M,x.x,M,x.x,xxxx*hh
1 = UTC of Position
2 = Latitude
3 = N or S
4 = Longitude
5 = E or W
6 = GPS quality indicator (0=invalid; 1=GPS fix; 2=Diff. GPS fix)
7 = Number of satellites in use [not those in view]
8 = Horizontal dilution of position
9 = Antenna altitude above/below mean sea level (geoid)
10 = Meters (Antenna height unit)
11 = Geoidal separation (Diff. between WGS-84 earth ellipsoid and
mean sea level. -=geoid is below WGS-84 ellipsoid)
12 = Meters (Units of geoidal separation)
13 = Age in seconds since last update from diff. reference station
14 = Diff. reference station ID#
15 = Checksum