International Telemetering Conference Proceedings / October 13-15, 1981 / Bahia Hotel, San Diego, CaliforniaThe Tracking and Data Relay Satellite System (TDRSS) is a shared service system supplying leased communication and tracking services to NASA and commercial Advanced Westar channels to Western Union and the American Satellite Company. An overview of the TDRSS design is presented. The space segment, consisting of four geosynchronous satellites, is described including launch. The spacecraft is described with emphasis on the communications payload covering both the NASA TDRSS and Advanced Westar equipment. The ground terminal located at White Sands, New Mexico, serves as the interface between the four TDRSs and up to 32 user satellites si...