OEM7 SPAN Installation and Operation User Manual v14
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Chapter 4 SPAN with Dual Antenna
NovAtel's ALIGN
®
heading technology generates distance and bearing information between a “master” and one
or more “rover” receivers.
SPAN with Dual Antenna provides the hardware necessary to run an ALIGN baseline with an IMU and a second
receiver.
With SPAN, the ALIGN GNSS baseline can be used to assist the initial alignment of the SPAN solution. In addi-
tion, the ALIGN baseline solution will aid the heading solution from the receiver if the heading drifts due to slow or
constant dynamics.
ALIGN is capable of a 10 Hz heading output rate when integrated with the OEM7 receiver.
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 the
INSCALIBRATE
command for
details.
4.1 Installation
The hardware for SPAN with Dual Antenna is installed in a manner similar to other SPAN systems. Some points
to consider during your installation are:
1. Install the IMU and the two antennas in the vehicle such that the relative distance between them is fixed.
2. The antennas should be mounted as a similar height, relative to the IMU, where the view of the satellites will
not be obstructed by any part of the vehicle. As heading accuracy is dependent on baseline length, mount
the antennas as far apart as possible. A minimum separation distance of 1 meter is recommended.
3. The lever arms or distance from the IMU to the antennas needs to be fixed and accurately measured using
the coordinate axes defined on the outside of the IMU. The baseline between the two antennas does NOT
need to be aligned with the vehicle axes or with the axes of the IMU.
4. Both receivers need to be powered and connected to each other via COM 2 before sending any configuration
commands. It does not matter which receiver is powered on first, or how long they are both powered before
sending any commands.
SPAN with Dual Antenna operation assumes the use of the COM 2 port for communication between
receivers unless a different port is specified using the
INSALIGNCONFIG
command. This command
can change the COM ports of the SPAN-enabled master and the rover, the baud rate used and data out-
put rates.
For information about connecting the ALIGN master and rover receivers using a port that is not a serial
COM port (e.g. Ethernet), contact NovAtel Customer Support.
The two receivers need to be set up as shown in the example in
