Carrier demand assignment in multiple-access space communications systems

Methods of telephonic and other forms of communications mediated by earth satellite with time-division or frequency-division multiple-access (TDMA, FDMA) arrangements are described. Permanent or free demand assignment procedures, use of satellite communications to multiply information carrying capacity, global beams and spot beams, and ways of keeping channels open for users are discussed. The SPADE (single channel per carrier PCM multiple access demand assignment equipment) system in use on the Intelsat IV satellite and its functioning are described, along with the use of modems, codec, and common signaling channels. Ways of economizing on satellite broadcast power and communications capacity are discussed.