ABSTRACT

The broadcast industry, and virtually all communications services, is dependent on reaching people within a given area. The quality of coverage is a key factor. Knowing where the signal goes, through propagation prediction, is both science and art. It is based on the scientific modeling of the radio path as it travels from the transmitter to the receiver. A good model can accurately predict signal strength at various frequencies over distances as those signals are influenced by ground conductivity, atmospherics, and terrain. The propagation models currently in use were developed and tested over a period of time and have been adjusted to better account for observed variances. How information gleaned from propagation predictions is presented to the broadcaster is an art and an important part of making sense of what the predictions mean. In this chapter, the primary broadcast-oriented prediction models currently used in the United States are discussed, and information on how radio and television station engineers can use the models to assess the performance of their systems is provided.