GLOBALSAT ET-314 GPS Engine Board - Manual (Page 13)

ET-314AC
High Performance GPS Engine Board
2010/4/1
- 13 -
are geodetic WGS84 directions relative to true North.
VTG - Course Over Ground and Ground Speed
Note – Fields marked in italic
red
apply only to NMEA version 2.3 (and later) in this NMEA
message description
Table A-7 contains the values for the following example:
$GPVTG,309.62,T,,M,0.13,N,0.2,K,A*23
Table A-7 RMC Data Format
Name Example Units Description
Message ID $GPVTG VTG protocol header
Course 309.62 degrees Measured heading
Reference T True
Course degrees Measured heading
Reference M Magnetic 1
Speed 0.13 knots Measured horizontal speed
Units N Knots
Speed 0.2 Km/hr Measured horizontal speed
Units K Kilometers per hour
Mode A A=Autonomous, D=DGPS, E=DR
N=Output Data Not Valid
Checksum *23
<CR><LF> End of message termination
SiRF Technology Inc. does not support magnetic declination. All “course over ground” data are
geodetic WGS84 directions.