Carrier rediffusion

Radio rediffusion employs the telephone network for the dissemination of radio broadcast programmes but need not be confined to telephone subscribers. As compared to radio transmission, particularly in the long-wave range, telephone lines provide superior transmission conditions and, further, comparatively low power may be employed while providing sufficiently high potentials for reliable and interference-free reception. In a telephone cable network the unamplified rediffusion range is equivalent to approximately 6-8 km. of subscriber's cable. Experience has shown that the number of programmes that can be furnished is not limited by a dearth of carrier frequencies but rather by an insufficiency of available broadcast programmes. Each transmitter produces a carrier frequency with the range of 150-300 kc./sec. At the end of a subscriber's line the rediffusion frequencies pass through a receiving filter to one or more receivers. Thus the subscribers in a block of flats or in adjacent buildings may be supplied with the service over a single telephone line. The carrier frequencies used are such that they can be received on any long-wave radio receiver. A number of figures illustrating the equipment are included in the paper.