Linx Technologies RXM-GPS-FM - Manual (Page 9)

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NMEA Output Messages
The following sections outline the data structures of the various NMEA
messages that are supported by the module. By default, the NMEA
commands are output at 9,600bps, 8 data bits, 1 start bit, stop bit, and no
parity.
Six messages are output at a 1Hz rate by default. These messages are
shown in Figure 8.
Details of each message and examples are given in the following sections.
GGA – Global Positioning System Fix Data
Figure 9 contains the values for the following example:
$GPGGA,053740.000,2503.6319,N,12136.0099,E,1,08,1.1,63.8,M,15.2,M,,0000*64
Global Positioning System Fix Data Example
Name Example Units Description
Message ID $GPGGA GGA protocol header
UTC Time 053740.000 hhmmss.sss
Latitude 2503.6319 ddmm.mmmm
N/S Indicator N N=north or S=south
Longitude 12136.0099 dddmm.mmmm
E/W Indicator E E=east or W=west
Position Fix Indicator 1 See Figure 10
Satellites Used 08 Range 0 to 33
HDOP 1.1 Horizontal Dilution of Precision
MSL Altitude 63.8 meters
Units M meters
Geoid Separation 15.2 meters
Units M meters
Age of Diff. Corr. second Null fields when DGPS is not used
Diff. Ref. Station 0000
Checksum *64
<CR> <LF> End of message termination
Position Indicator Values
Value Description
0 Fix not available or invalid
1 GPS SPS Mode, fix valid
2 Differential GPS, SPS Mode, fix valid
3–5 Not supported
6 Dead Reckoning Mode, fix valid (requires external hardware)
Figure 9: Global Positioning System Fix Data Example
Figure 10: Position Indicator Values
NMEA Output Messages
Name Description
GGA Contains the essential fix data which provide location and accuracy
GLL Contains just position and time
GSA Contains data on the Dilution of Precision (DOP) and which satellites are used
GSV
Contains the satellite location relative to the receiver and its signal to noise
ratio. Each message can describe 4 satellites so multiple messages may be
output depending on the number of satellites being tracked.
RMC Contains the minimum data of time, position, speed and course
VTG Contains the course and speed over the ground
Figure 8: NMEA Output Messages