Message Type 83, $GPVTG

Standard NMEA message containing heading and speed information relative to the ground.

NMEA 0183 v2.0 message format is:

$GPVTG,aaa.a,T,,M,bbb.b,N,ccc.c,K*hh<CR><LF>

NMEA 0183 v3.0 message format is:

$GPVTG,aaa.a,T,,M,bbb.b,N,ccc.c,K,e*hh<CR><LF>

Where:

aaa.a is the heading over ground in degrees (relative to true north)

bbb.b is the horizontal velocity over ground in knots

ccc.c is the horizontal velocity over ground in km/h

e is the positioning system mode indicator (NMEA 0183 v3.0 only): A = autonomous mode, D = Differential mode, E = Estimated (dead reckoning) mode, M = Manual input mode, S = Simulator mode, N = Data not valid. Note: The CTM internal GPS module supports autonomous mode only.

hh is the message checksum

Examples:

NMEA 0183 v2.0:

$GPVTG,180.0,T,,M,031.7,N,058.8,K*69

NMEA 0183 v3.0:

$GPVTG,023.0,T,,M,029.8,N,055.2,K,A*0D