Abstract: An acoustic coupler is provided for extending the listening and signal garing capabilities of an existing cable connected hydrophone system. The acoustic coupler includes a sensor, such as an additional hydrophone, an acoustic projector, and a cable which electrically connects the acoustic projector to the additional hydrophone. A modulator is interconnected in the cable between the projector and the additional hydrophone for modulating signals received by the additional hydrophone on a carrier wave which is within the bandpass of the existing hydrophone. With this arrangement the acoustic projector can be placed in water within listening distance of the existing hydrophone so that signals from the additional hydrophone can be transmitted over the existing hydrophone and its cable system.

Abstract: A tethered underwater work system comprises a primary lift module attached o a support vehicle by means of a primary tether. A submarine work vehicle is removably attached to said primary lift module and connected thereto by means of a secondary tether. Additionally, the lift module contains electrical distribution systems to permit an extensive control and instrumentation linkage with the submarine work vehicle and remotely controlled manipulators mounted thereon.