Planning methods for a national single frequency network for DAB

The transmission system developed within Eureka 147 for DAB is known as coded orthogonal frequency division multiplex (COFDM). By dividing the digital data amongst a very large number of low bit rate carriers the COFDM system provides a very high degree of tolerance towards multipath interference. It follows from this that a national network of cochannel transmitters can be developed such that not only do neighbouring transmitters cause mutual interference but can combine in a constructive manner. This is the principle of the single frequency network (SFN). The paper describes the structure and operation of the computerised prediction methods developed by the BBC for the modelling and planning of COFDM single frequency networks, and presents some of the results obtained to date