Chapter 4 SPAN with Dual AntennaOEM7 SPAN Installation and Operation User Manual v4 111The rover receiver must be an ALIGN-capable model.To enable the dual-antenna ALIGN solution to aid the INS alignment and provide headingupdates, the offset between the antennas and the IMU must be known. This is achieved by enter-ing lever arms to both antennas, using the SETINSTRANSLATION command.To configure SPAN with ALIGN Aiding:1. Enter the lever arm from the IMU to the primary antenna (primary antenna is connected tothe SPAN receiver).Abbreviated ASCII example:SETINSTRANSLATION ANT1 0.54 0.32 1.20 0.03 0.03 0.052. Enter the lever arm from the IMU to the secondary antenna (secondary antenna is connectedto the second receiver or the secondary input on dual antenna receivers).Abbreviated ASCII example:SETINSTRANSLATION ANT2 0.54 2.32 1.20 0.03 0.03 0.05Alternately, the angular offset between the dual-antenna baseline (from primary GNSS antennato secondary GNSS antenna) and the IMU frame forward axis is entered directly via the ALIGNparameter of the SETINSROTATION command.We recommend entering the lever arms rather than entering the angular offset as this iseasier to measure and will lead to better overall accuracy.Refer to the OEM7 Commands and Logs Reference Manual for the syntax of the above com-mands.As with all ALIGN-capable products, the GNSS baseline solution is available from the GPHDT logand HEADING2 log. For INS heading, use the INSATT log or INSPVA log.The SPAN system can be configured for different alignment routines depending on the motionconditions experienced during the alignment period. For example, in marine applications, thedynamics required for either a coarse or kinematic alignment cannot be guaranteed, so a dif-ferent alignment routine is required.The different alignment routines are described in Configuring SPAN with ALIGN below.4.3 Configuring SPAN with ALIGNThe SPAN receiver can be configured for different alignment routines depending on the motionconditions experienced during the alignment period. For example, in marine applications, thedynamics required for either a coarse or kinematic alignment cannot be guaranteed, so a dif-ferent alignment routine will be required.Before the ALIGN heading can be computed and used by SPAN, both GNSS antennaemust have a clear view of the sky.
