Implementation of secure voice (STU-III) into the land mobile satellite system

One of the responsibilities of the National Communications System is the incorporation of a secure telephone unit (STU-III)-based secure voice capability into the land mobile satellite service (LMSS) of the United States. As part of this effort, the NCS funds an effort at the Jet Propulsion Laboratory (JPL) to perform system studies, analyses, and field trials of prototype equipment. The first experiment involving STU-III's in a mobile satellite application was carried out by JPL in 1989 in Australia, using the Japanese experimental satellite ETS V. Subsequent work has included laboratory testing of recently developed STU-III interfaces, refinements to mobile satellite link characteristics simulation, and interaction on system architectural issues with the American Mobile Satellite Corporation (AMSC). The authors describe the projected role of LMSS secure voice in satisfying NCS national security and emergency preparedness requirements, and the issues remaining to be resolved before secure voice becomes an integral part of AMSC's services that are projected to commence in 1993. >