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 with as clear a view of the sky as possible so each satellite above the horizon can be tracked with minimal obstruction. If using a dual antenna system, the GNSS ALIGN accuracy is dependent on antenna baseline length; hence mount the primary and secondary antennas as far apart as possible (a minimum separation distance of 1 metre is recommended).

   In most scenarios, it is ideal to use the antenna closest to the IMU as the primary. However, it may be use case dependent given the installation location of both antennas.

   For more information, refer to Mounting the GNSS Antenna.

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 base and the rover, the baud rate used and data output rates.

For information about connecting the ALIGN base 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 Figure: SPAN – Two Receiver Dual Antenna Installation.

Dual antenna receivers, such as the OEM7720 and PwrPak7D, contain the hardware necessary to provide an ALIGN solution without an additional receiver. Set up a SPAN system with a dual antenna receiver as shown in Figure: SPAN – Single Receiver Dual Antenna Installation.