what is VTG

bitbanger:

ryan:
thats nice , thanx for explaination but what about calcutaion of Heading/Bearing ?

This is how I usually parse for data:

’ NMEA sentence usage:

’ $GPGGA : Time, Latitude, Longitude, number of Satellites in use

’ $GPRMC : Speed over ground, Course over ground, Date

’ $GPGSA : Fix type (none, 2D or 3D)

You need to look at the NMEA spec for $GPRMC for the bearing (“Course of ground”) It is in degrees…no math required.

but this the heading not the bearing …