Chapter 3 SPAN OperationOEM7 SPAN Installation and Operation User Manual v1 53IMU data:3.5 Real-Time OperationSPAN operates through the OEM7 command and log interface. Commands and logs are doc-umented in the OEM7 Commands and Logs Reference Manual (OM-20000169).Real-time operation notes:l By default, raw IMU data will begin to output as soon as the IMU is connected. However aninitial position is required to begin the INS alignment process. This position is typically set byGNSS. 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-Upand Alignment Techniques on the next page for more details.l The inertial solution is computed separately from the GNSS solution. The GNSS solution isavailable 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 theOEM7 Commands and Logs Reference Manual (OM-20000169).l The IMU raw data is available at the maximum rate of output of the IMU. Because of thishigh data rate, a shorter header format was created. These shorter header logs are definedwith an S (RAWIMUSXB rather than RAWIMUXB). We recommend you use these logs insteadof 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, seeTable 10: Inertial Solution Status below.Binary ASCII Description0 INS_INACTIVE IMU logs are present, but the alignment routine has not started; INS isinactive.Table 10: Inertial Solution Status
