The Mark III, ROV Locator bundle includes a transponder (usually mounted on the ROV or AUV) and a transceiver module (usually located on the surface). It also comes with a mounting ring and adapter for your ROV or AUV. ROV/AUV integration can be as simple as just supplying power from the vehicle battery. You can also add a dedicated battery for the Mark III to track the vehicle in case of primary battery failure. Simply apply power, start the dive and track the ROV location in real-time on a QGroundControl map display or use the free CeruleanMap display software if you don’t want to use QGC. Serial communication to either transceiver or transponder is available, and the open API is documented in the user manual.

In operation, the Mark III transceiver sends an interrogation sonar pulse to the transponder, which returns a sonar reply. The slant range is calculated from the round-trip time of flight. Unlike the Mark II systems, start-of-mission timebase synchronization is never needed. The Mark III system can remain submerged indefinitely without fear of slant range accuracy drift. Only one Mark III pair can operate in an area at one time.