A Family of SHF Tactical Satellite Communication Ground Terminals

On February 8, 1969, an experimental tactical communications satellite, TACSAT I, was successfully placed in synchronous orbit at the equator off the coast of South America. This paper concerns itself with a family of SHF tactical satellite communications ground terminals utilizing the SHF capability of that satellite. The material presented provides the system concepts necessary for the understanding of the ground terminals, their relationship to the satellite, and some insight into the design problems encountered during the development of a family of five types of terminals. The system concepts are presented in terms of communication modes, frequency assignments, and implementation of the respective modes. The beacon system for frequency control and signal acquisiticn siticn is described along with the factors involved in design of equipment implementing the analog FM, the alert message, frequency hopping, and, differential phase-shift keyed (DPSK) modes. The final configurations of each of the five terminals are described and illustrated through photographs and generalized block diagrams, and the capability of each is briefly outlined.