HOW SMALL CAN AN ELECTRO-OPTICAL TRANSOCEANIC CABLE BE?

Abstract

Design theory and analyses are presented for a transoceanic, electro-optical ( E-O), telemetry cable which---because its data, power and tensile functions can be separately optimized---has a very small diameter and transport volume. These reductions are achieved with no compromises of operational or material constraints on the telemetry system. For example, an ocean E-O cable which can directly support repeatered, multi-fiber telemetry between Japan and the United States will have a diameter less than 0.75 cm. Its transport volume will be barely 5% of that required for the smallest coaxial cable (SD List 1 with a 3.18-cm diameter) now being used in transoceanic communications. A cable design is demonstrated for a set of system parameters which define a 5550-kmlong “baseline” communications system. The study evaluates that system’s sensitivity to changes in such system parameters as length, repeater power and separation, water depth and safety factor, cable specific gravity, dielectric voltage stress, conductor conductivity, and the failure- or yield strains of loadbearing components. It is concluded that the cable should be relatively inexpensive. Its design can be tailored for specific applications with little change in manufacturing complexity or cost. The cost and risk of ocean deployment should be considerably reduced, since small ships can be loaded with ocean-crossing lengths of this miniature E-O cable.