ROV and remote data gathering control, communications, and power supply over a single inexpensive coaxial cable using a low power multiplex system

A need exists for a compact, low power, maintainable method for operating remote data gathering and control devices using inexpensive cable, When acquiring data or controlling events from a remote site, a system is required to communicate pertinent signals between the controlling station and the remote site. Common signals are digital or analog sensor data, video and sonar. In addition to sending data back from the remote site, it must also be supplied power and signals to control the on-board package. The use of multiconductor cable is common at this time. Often significant cross channel interference exists. On longer cables, the cost of this cable and the signal losses are often significant and prohibitive. Optic fiber is an alternative, but again the cost of cable and the specialized equipment used with optic fiber systems is often prohibitive. The system described in the paper was designed to be relatively inexpensive to build and maintain. The paper shows how a frequency multiplexed system can be designed using low power CMOS integrated circuits which not only eliminate the need for multiconductor cable, but also increase the workable length of the cable. The design of frequency multiplexed systems and power supply are covered with particular attention to cable characteristics requirements, and correlation of these requirements to commonly available coaxial cables. The use of superheterodyne type receivers to cabled underwater communications is covered in particular. The paper discusses the design and implementation of such a system to operate NSWCDD´s TONGS (Televised Observed Nautical Grappling System)