ashtech DG14, Reference Manual

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282 DG14 and DG16 Board & Sensor Reference Manual
VTG: Course and Speed Over the Ground
$PASHS,NME,VTG,x,c,[f]
This command enables or disables the velocity/course message on port x, where
x is the output port, c is ON or OFF, and f is the optional message output rate ranging
from 0.05 to 999 seconds depending on the measurement update rate option
installed.
The DG16 does not output this message unless it computes a position.
If the command is set without a period, the DG16 uses the period set by the
$PASHS,NME,PER command If the $PASHS,NME,PER command is issued after
this message period has been set, the period resets to the PER setting.
Example
Enter the following command to enable VTG message on port B.
$PASHS,NME,VTG,B,ON
$PASHQ,VTG,[c1]
This command queries the VTG message, where c1 is the optional port designator
for the output of the response. If a port is not specified, the receiver sends the
response to the current port.
$GPVTG
This message is not output unless positions are being computed. The VTG contains
course over the ground referenced to both true and magnetic north and speed over
the ground in kilometers per hour and nautical miles per hour (knots). The message
is output in the format:
$GPVTG,f1,c2,f3,c4,f5,c6,f7,c8,d9*hh
Table 8.55 outlines the message format.
Table 8.55. $GPVTG Response Structure
Field Description Range
f1 Course over ground; referenced to true north 000.00° to 359.99°
c2 North reference indicator (always T; true north) T
f3 Course over the ground; referenced to magnetic north 000.00° to 359.99°
c4 North reference indicator (always M; magnetic north) M
f5 Speed over ground (knots) 000.00 to 999.99
c6 Speed unit of measure (always N; nautical miles per hour) N
f7 Speed over ground (kilometers per hour) 000.00 to 999.99