INTELSAT IV Satellite System (Voice) Channel Capacity Versus Earth-Station Performance

A comprehensive technical study has been performed to assess the optimum voice-channel capacity of a transponder as a function of the earth-station performance (ratio of receive antenna gain to system noise temperature) for various modulation techniques such as: a) single-carrier per transponder frequencydivision multiplexing frequency modulating (FDM/FM); b) multicarrier per transponder FDM/FM; c) pulse-code modulating, coherent phase-shift keying, time-division multiple access (PCMCPSK-TDMA); and d) SPADE (single-channel per carrier PCMCPSK-FDMA), which will be used in the INTELSAT IV satellite system. This study assumes a homogeneous system, i.e., the transmit and receive earth stations use an appropriately identical antenna performance.