Polycasting

Polycasting is a method applicable to very-high-frequency and ultra-high-frequency bands for broadcasting a program from a number of low-powered stations instead of from a single high-powered one with the object of covering a continuous area. It may be regarded as a special application of satellite operation, making use of the fact that at high frequencies the signal intensity varies over a wide range from point to point so that the service must be evaluated on a statistical basis. The paper is a theoretical study of the service obtainable. It is shown that to provide a large percentage of the locations in an area with good service requires far more power from a single station than from several stations. This effective power gain is over and above the simple gain from better "illumination" of a large area when served by several sources instead of concentrating all the power at one point. A special application of the system to serve rural areas is explained. It is there proposed to locate the component stations of the polycasting system in small towns, so located that a rural grade of service is provided by them in the area between them. Estimates of service are given, taking into account ghosts and signal intensity required to overcome noise. There is also laid out tentative allocation of stations in two typical areas