Technical aspects of the design of communication-satellite systems

The paper surveys some of the technical problems involved in the design of communication-satellite systems providing substantially worldwide coverage for the transmission of multichannel telephony and television signals. Factors affecting the choice of orbit and type of satellite are discussed, and it is concluded that attitude-stabilised, station-keeping satellites in medium-altitude circular orbits represent a desirable design objective. The operational and performance requirements for multichannel telephony and television are considered in the light of the findings of the international Radio Consultative Committee at its Xth Plenary Assembly (Geneva, 1963). Technical factors, such as the choice of frequency and modulation method, are discussed, with particular reference to the problem of providing multistation access to satellites. The limitations on satellite and terrestrial radio-relay system transmitter power imposed by the need to share the same frequency bands are examined, and the advantages of using preferred radio-frequency channelling arrangements by both systems are discussed. Finally, an outline is given of one possible approach to the design of a worldwide system using twelve station-keeping, attitude-stabilised satellites in a subsynchronous (8h) orbit at 14000km height in the equatorial plane of the Earth.