NMEA-0183 message: VTG

Track made good and speed over ground

NOTE – The heading computation in this message is derived from consecutive positions. For heading using a moving baseline system, see NMEA-0183 message: PTNL,AVR.

An example of the VTG message string is:

$GPVTG,140.88,T,,M,8.04,N,14.89,K,D*05

VTG message fields

Field	Meaning
0	Message ID $GPVTG
1	Track made good (degrees true)
2	T: track made good is relative to true north
3	Track made good (degrees magnetic)
4	M: track made good is relative to magnetic north
5	Speed, in knots
6	N: speed is measured in knots
7	Speed over ground in kilometers/hour (kph)
8	K: speed over ground is measured in kph
9	Mode indicator: A: Autonomous mode D: Differential mode E: Estimated (dead reckoning) mode M: Manual Input mode S: Simulator mode N: Data not valid
10	The checksum data, always begins with *