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SPAN Operation Chapter 3
SPAN-IGM User Manual Rev 2 33
Specific logs need to be collected for post-processing. See Data Collection for Post-Processing on
page 36.
To store data from a SPAN-IGM, connect the SPAN-IGM to a computer running NovAtel Connect or other
terminal program capable of recording data.
3.2.4 Vehicle to SPAN Frame Angular Offsets Calibration Routine
Kinematic alignment requires that the angular offset between the vehicle and SPAN frame is known
approximately. If the angles are simple (that is, a simple rotation about one axis) the values can easily be
entered manually through the VEHICLEBODYROTATION command. If the angular offset is more
complex (that is, rotation is about 2 or 3 axis), then the calibration routine provides a more accurate
estimation of the values. The vehicle to SPAN frame angular offset calibration requires RTK GPS. The
steps for the calibration routine are:
1. Apply power to the SPAN-IGM.
2. Configure the IMU, see SPAN IMU Configuration on page 24.
3. Ensure that an accurate lever arm has been entered into the system.
4. Allow the system to complete an alignment, see System Start-Up and Alignment Techniques on
page 30.
5. Enable the vehicle to body calibration using the RVBCALIBRATE ENABLE command.
6. Start to move the system. Movement of the system is required for the observation of the angular
offsets.
Drive a series of manoeuvres such as figure eights if the driving surface is not level, or a straight
course if on level ground (remember that most roads have a crown resulting in a constant roll of a
few degrees). Avoid driving on a surface with a constant, non-zero, slope to prevent biases in the
computed angles. Vehicle speed must be greater than 5 m/s (18 km/hr) for the calibration to
complete.
Logging Restriction Important Notice
Logging excessive amounts of high rate data can overload the system. When configuring
the output for SPAN, NovAtel recommends that only one high rate (>50 Hz) message be
configured for output at a time. It is possible to log more than one message at high rates,
but doing so could have negative impacts on the system. Also, if logging 125 or 200 Hz
data, always use the binary format and, if possible, the short header binary format
(available on most INS logs).
For optimal performance, log only one high rate output at a time. These logs could be:
• Raw data for post processing
RAWIMUXSB ONNEW (125 or 200 Hz)
- RAWIMU logs are not valid with the ONTIME trigger. The raw IMU observations
contained in these logs are sequential changes in velocity and rotation. As such,
you can only use them for navigation if they are logged at their full rate. See details
of these logs in the SPAN on OEM6 Firmware Reference Manual (OM-20000144).
• Real time INS solution
INSPVASB ONTIME 0.005 (maximum rate equals the IMU rate)
- Other possible INS solution logs available at high rates are: INSPOSSB,
INSVELSB, INSATTSB