COLOCATED COMSTARS

Abstract

Both AT&T and GSAT are presently using the COMSTAR to expand and diversify their domestic public dial telephone networks. COMSAT General’s TTC&M earth station facilities at Southbury, Connecticut, and Santa Paula California, continuously monitor the status of the COMSTARs. For the purpose of increasing the likelihood of availability and maximizing the number of communications transponders to the users, at the end of the spacecraft design lifetime, COMSAT General was able to reach a business agreement with AT&T and obtain FCC authorization to launch COMSTAR D-4 and colocate D-1 and D-2. Therefore, as far as the communications earth stations are concerned, colocated D-1 and D-2 with a coordinated 24 TWT configuration are technically identical to a single COMSTAR satellite. There is, however, a significant increase in satellite lifetime due to reduced solar array and battery loading (about half) since each satellite now operates with twelve TWTs on instead of the usual twenty-four for a COMSTAR. This paper will describe the TTC&M earth stations’ modification to accommodate the colocated satellites. Operational considerations and some actual operational experience will also be discussed.