Broadcasting from Satellites—UHF Television Channel Utilization

Abstract

One of the factors that affect satellite broadcasting systems is the choice of modulation, whether it should be AM-VSB, as we have it in terrestrial broadcasting, or frequency modulation (FM). The latter is chosen for a theoretical satellite television system in the UHF-TV band based on the latest CCIR figures. From this the required field strength and satellite transmitter power are calculated. The required protection ratio is used to calculate the angular separation between satellites when using the same channel. An allocation of two and four channels to each of two satellites is used to determine the number of independent programs which could be made available in Canada, assuming the country is divided into four areas covered by two synchronous geostationary satellites. It is shown that four channels allocated to each of two adjacent satellites would provide a total of eight independent programs to the four areas without the necessity of having the satellites very widely separated, as might appear from preliminary observation. Finally, a practical example for Canadian coverage is presented.