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:


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 *