ashtech DG16 Reference Manual page 303

Field
c8 Speed unit of measure (always K; KPH)
d9 Positioning system mode indicator
• A—Autonomous mode
• D—Differential mode
• E—Estimated (dead reckoning) mode
• M—Manual input mode
• S—Simulator mode
• N—Data not valid
*hh Checksum
Typical VTG message:
$GPVTG,179.00,T,193.00,M,000.11,N,000.20,K*3E
Table 8.56 outlines the response message.
$GPVTG
179.00
T
193.00
M
000.11
N
000.20
K
*3E
NMEA Commands
Table 8.55. $GPVTG Response Structure
Description
Table 8.56. Typical VTG Message
Field
Header
Course over ground (degrees)
True course over ground marker
Magnetic course over ground
Magnetic course over ground marker
Speed over ground (knots)
Nautical miles per hour
Speed over ground in kilometers/hour
Kilometers per hour
Checksum
Description
Range
K
A, D, E, M, S, or N
2-character hex
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