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CONFIGURE THE SPAN SYSTEM
Follow these steps to enable INS as part of the SPAN system using software commands.
1. Establish a connection to the SPAN CPT7.
A GNSS antenna must be connected and tracking satellites for operation.
2. Enter the distance from the SPAN CPT7 center of navigation to the phase center of the GNSS
antennas using the SETINSTRANSLATION command. Use SETINSTRANSLATION ANT1 for the
distance to the primary GNSS antenna and SETINSTRANSLATION ANT2 for the distance to the
secondary GNSS antenna.
The offset between the antenna phase center and the SPAN CPT7 axes must remain constant and be
known accurately. The X (pitch), Y (roll) and Z (azimuth) directions are clearly marked on the
SPAN CPT7. The SETINSTRANSLATION parameters are (where the standard deviation fields are
optional):
x_offset y_offset z_offset [x_stdev] [y_stdev] [z_stdev]
The measurements for the translational offsets should be done as accurately as
possible, preferably to within millimetres especially for RTK operation. Any error in the
offsets will translate into an error in the INS position.
3. The SPAN-CPT7 comes pre-configured with an RBV of 180 0 90. This configuration is valid if
mounting is done as described in SPAN CPT7 Mounting on page 5. If the SPAN CPT7 is mounted in
an orientation other than the default orientation, the SETINSROTATION command must be sent. Using
the RBV parameter, enter the Euler Angle rotation from the IMU Body frame to the Vehicle frame.
Accurate knowledge of the rotational offset between the IMU Body frame and the Vehicle frame (the
RBV rotation) is critical to correctly computing an attitude solution, and is required before a Kinematic
alignment is possible.
The SETINSROTATION parameters are (where the standard deviation fields are optional):
RBV x_rotation y_rotation z_rotation [x_stdev] [y_stddev] [z_stdev]
The order of rotations is Z-X-Y. All rotations are right handed.
Configuration for Alignment
The SPAN CPT7 can use a kinematic alignment routine or a dual antenna alignment. The kinematic or
moving alignment is performed by estimating the attitude from the GNSS velocity vector and injecting it
into the SPAN filter as the initial system attitude. A dual antenna alignment uses the heading information
from a NovAtel Dual Antenna ALIGN solution to rapidly perform an alignment. For information about these
alignment techniques, refer to the OEM7 User Documentation (docs.novatel.com/OEM7).
Regardless of system configuration and IMU orientation, the SETINSTRANSLATION
command must be sent to the receiver before attempting a kinematic alignment.
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