Chapter 3 SPAN Operation
OEM7 SPAN Installation and Operation User Manual v14
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Since slight variations in alignment can be introduced when the IMU or PwrPak7-E1 is remounted, a
Body to Vehicle Frame calibration should be performed each time the device is remounted.
An accurate RBV is especially important if the position is being transferred to a user offset.
3.4 Real-Time Operation
SPAN operates through the OEM7 command and log interface. Refer to the
log and command details. .
Real-time operation notes:
l
By default, raw IMU data will begin to output as soon as the IMU is connected. However an initial position is
required to begin the INS alignment process. This position is typically set by GNSS. The GNSS position will
not be used until the FINESTEERING time status is reached. This requires a GNSS antenna connected with
a clear view of the sky. See
System Start-Up and Alignment Techniques
on the next page for more details.
l
The inertial solution is computed separately from the GNSS solution. The GNSS solution is available from
the SPAN system through the GNSS-specific logs, even without SPAN running. The integrated GNSS+INS
solution is available through special INS logs documented in INS Logs in the
l
The IMU raw data is available at the maximum rate of output of the IMU. Because of this high data rate, a
shorter header format was created. These shorter header logs are defined with an S (RAWIMUSXB rather
than RAWIMUXB). We recommend you use these logs instead of the standard header logs to save through-
put on the COM port.
Status of the inertial solution can be monitored using the inertial status field in the INS logs, see
Binary
ASCII
Description
0
INS_INACTIVE
IMU logs are not yet present or the alignment routine is not yet initialized. INS state is
inactive.
1
INS_ALIGNING
INS is in alignment mode.
2
INS_HIGH_
VARIANCE
The INS solution uncertainty contains outliers and the solution may be outside
specifications. The solution is still valid but you should monitor the solution
uncertainty in the
INSSTDEV
log. It may be encountered during times when GNSS is
absent or poor.
3
INS_
SOLUTION_
GOOD
The INS solution is in navigation mode and has converged sufficiently to be within
specifications.
For a more rigorous check of the INS solution, examine bit 6 of the Extended Solution
Status word. The Extended Solution Status word is available in several logs,
including
INSATTX
log,
INSPOSX
log,
INSSTDEV
log,
INSSTDEVS
log,
INSVELX
log and
INSUPDATESTATUS
log
Table 22: Inertial Solution Status
