Chapter 4 SPAN with Dual Antenna
OEM7 SPAN Installation and Operation User Manual v14
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The rover receiver must be an ALIGN-capable model.
To enable the dual-antenna ALIGN solution to aid the INS alignment and provide heading updates, the offset
between the antennas and the IMU must be known. This is achieved by entering 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.
Abbreviated ASCII example:
SETINSTRANSLATION ANT1 0.54 0.32 1.20 0.03 0.03 0.05
2. Enter the lever arm from the IMU to the secondary antenna.
Abbreviated ASCII example:
SETINSTRANSLATION ANT2 0.54 2.32 1.20 0.03 0.03 0.05
Alternately, the angular offset between the dual-antenna baseline (from primary GNSS antenna to secondary
GNSS antenna) and the IMU frame forward axis is entered directly via the
ALIGN
parameter of the
SETINSROTATION
command.
We recommend entering the lever arms rather than entering the angular offset as this is easier to meas-
ure and will lead to better overall accuracy.
Refer to the
OEM7 Commands and Logs Reference Manual
for the syntax of the above commands.
As with all ALIGN-capable products, the GNSS baseline solution is available from the
GPHDT
log and
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 motion conditions exper-
ienced during the alignment period. The different alignment routines are described in
4.3 Configuring SPAN with ALIGN
The SPAN receiver can be configured for different alignment routines depending on the motion conditions exper-
ienced during the alignment period. For example, in marine applications, the dynamics required for either a
coarse or kinematic alignment cannot be guaranteed, so a different alignment routine will be required.
Before the ALIGN heading can be computed and used by SPAN, both GNSS antennas must have a
clear view of the sky.
For optimal SPAN performance when using Dual Antenna with SPAN, an ALIGN offset calibration is
required for each unique installation. This calibration refines the IMU to antenna baseline angular offset
from the initial estimate derived from the input lever arms. Refer to
INSCALIBRATE
command for
details.
The different alignment routines are described in the following sections: