Real-Time Operation

SPAN operates through the OEM7 command and log interface.

Real-time operation notes:

• 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 for more details.

• 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 SPAN Logs.

• 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 throughput on the COM port.

Status of the inertial solution can be monitored using the inertial status field in the INS logs.

Inertial Solution Status

Binary	ASCII	Description
0	INS_INACTIVE	IMU logs are present, but the alignment routine has not started; INS 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.1 The solution uncertainty threshold levels can be adjusted using the INSTHRESHOLDS command. 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 filter is in navigation mode and the INS solution is good.
6	INS_SOLUTION_FREE	The INS Filter is in navigation mode and the GNSS solution is suspected to be in error. The inertial filter will report this status when there are no available updates (GNSS or other) being accepted and used.
7	INS_ALIGNMENT_COMPLETE	The INS filter is in navigation mode, but not enough vehicle dynamics have been experienced for the system to be within specifications.
8	DETERMINING_ORIENTATION	INS is determining the IMU axis aligned with gravity.
9	WAITING_INITIALPOS	The INS filter has determined the IMU orientation and is awaiting an initial position estimate to begin the alignment process.
10	WAITING_AZIMUTH	The INS filer has orientation, initial biases, initial position and valid roll/pitch estimated. Will not proceed until initial azimuth is entered.
11	INITIALIZING_BIASES	The INS filter is estimating initial biases during the first 10 seconds of stationary data.
12	MOTION_DETECT	The INS filter has not completely aligned, but has detected motion.
14	WAITING_ALIGNMENTORIENTATION	The INS filter is waiting to start alignment until the current Vehicle Frame roll and pitch estimates are within the configured threshold of the expected orientation (set by the SETALIGNMENTORIENTATION command). Note: This requires an accurate RBV rotation to be configured, see the SETINSROTATION command.