The B.B.C. sound broadcasting service on very high frequencies

The paper describes the developments leading to the inauguration of the B.B.C. very-high-frequency service of sound broadcasting, which works in the band 87.5¿100Mc/s. The need for a very-high-frequency service is explained, and the considerations leading to the choice of frequency modulation rather than amplitude modulation, and of the national planning standards, are summarized. In July, 1954, the Postmaster General authorized the first stage of the development plan, comprising nine stations. Later it was agreed that another station should be included in this stage, which is now virtually complete. In July, 1956, the B.B.C. was given authority to build a further six stations, which will be in service early in 1958. These sixteen stations will cover 96% of the population of Great Britain and Northern Ireland with three programmes. At a later date the B.B.C. plans to build additional stations to extend the population coverage to about 98%. At the majority of the stations three programmes are radiated from a common aerial; special precautions are taken to minimize the generation of intermodulation terms. The experience gained during the first year´s service is described, with special reference to the performance of commercial receivers. The present stage of development of very-high-frequency sound-broadcasting services abroad is briefly summarized.