Mounting positions of the transmitter or receiver can be interchanged topside or deepside. The receiver should generally be located close to where location or orientation information is needed (the transmitter will never have any idea of its location, angle to receiver, or range to receiver). Both units should be mounted where they will not receive mechanical blows or other mechanical shocks.
Note that Cerulean Sonar releases new firmware for ROVL systems several times per year. While there is no need to install firmware updates if your system is working as you like, the updates often contain new features and enhancements as well as bug fixes.
If you want to keep the ability to install firmware updates, keep the following in mind as you mount and wire the units:
The unit being updated will need to be connected to a Windows PC running CeruleanTracker software during the update process (after updating you can return the system to its normal configuration). Normally this requires a serial-to-USB adapter such as an FTDI cable, a Blue Robotics BLUART adapter, or some other form of adapter.
A serial-port forwarding scheme will most likely not work for firmware updating because the ROVL CPU chips require non-standard serial parameters and intricate timing during the update.
If the unit being upgraded has had a failed update (for example, a power drop-out during the update process) and cannot assist in its own update, you may need to be able to access the base of the unit with an electrical fixture (see the CeruleanTracker manual for more detail).