Feasibility study of non-invasive telemetry techniques for use with submarine telephone cables

Abstract

The feasibility of using inductive coupling with existing submarine telephone cables for telemetry of data from ocean sensors was investigated. The submarine telephone cable was simulated with a computer model and the model results were tested experimentally by deploying 600 meters of coax cable in Woods Hole Harbor. In parallel a study of the optimum access methods and modulation and techniques was performed. Results of the feasibility study showed that a non-invasive technique for inductive coupling is not feasible for use with existing SF and SD coaxial cable designs. Signals induced in both conductors by a toroid encircling the cable remain identical as they propagate along the cable as a result of mutual inductance. Thus, no signals are apparent at the repeaters. Optimal use of cable bandwidth combines time division multiple access with trellis-coded QAM modulation.