
Chapter 4 SPAN Operation
SPAN CPT7 Installation and Operation User Manual v3A
90
4.7.1 Course Over Ground
The course over ground azimuth is determined using the position delta between two position
solutions computed by the OEM7 receiver. This is the simplest way to compute an azimuth and is
done using either the GNSS solution or the INS solution. This method does not work when the
vehicle is stationary as any position difference is due to position error and the computed azi-
muth is meaningless.
Course over ground azimuth is of greatest advantage in aerial or marine environments where
the actual direction of travel may not match the forward axis of the aircraft/boat due to winds or
currents. This effect is known as the crab angle. Course over ground azimuth is a great way to
compute the offset if another means of computing the vehicle azimuth is available.
Course over ground azimuths are available in several different velocity logs. See
4.7.2 Inertial Azimuth
The inertial azimuth computed by the SPAN inertial navigation filter. It uses the sensors in the
IMU to compute the azimuth of the IMU (this can be rotated to another reference if desired). For
more information, see the
SETINSROTATION
command in the
This azimuth is the one provided in the majority of the INS logs available to a SPAN user. See
Table 9: Logs with Azimuth Data
4.7.3 ALIGN Azimuth
On SPAN systems with dual antennas, an azimuth is available from the dual antenna baseline.
This is the same azimuth that is used as an update to the SPAN solution. It is noisier than the
inertial azimuth and is available at a much lower rate, but will have a stable mean. This azimuth
is computed from the master antenna to the rover antenna based on how the antennas are ori-
ented on the vehicle.
There is a specific subset of logs that output this azimuth. See
Table 9: Logs with Azimuth Data
Log
Log
Format
Azimuth Source
BESTGNSSVEL
NovAtel
Course Over Ground
From the best GNSS only solution
BESTVEL
NovAtel
Course Over Ground
From the best system solution which could be either
GNSS or INS
GPHDT
NMEA
ALIGN
Table 9: Logs with Azimuth Data
Содержание SPAN CPT7
Страница 1: ...OM 20000179 v3A January 2019 SPAN CPT7 Installation and Operation User Manual ...
Страница 141: ...Chapter 10 NovAtel Firmware and Software SPAN CPT7 Installation and Operation User Manual v3A 141 ...
Страница 167: ...APPENDIX D Importance of Antenna Selection SPAN CPT7 Installation and Operation User Manual v3A 167 ...