Analogue-to-digital and digital-to-analogue conversion for broadcast quality sound

A 13-channel p.cm. system forms a significant part of the BBC´s national radio distribution network, and is used to carry high-quality soundprogramme material hundreds of miles with minimal impairment from noise, interference and distortion. High-quality analogue-to-digital converters (a.d.c) and digital-to-analogue converters (d.a.c) are required for use in sound-programme links, and other applications for these converters, such as digital sound studio equipment, can be foreseen, To date, the BBC has used 13-bit a.d.cs and d.a.cs developed within the Corporation. The next generation of digital equipment is likely to require coders and decoders giving 14 bits/sample or even higher resolution. In this paper, some of the defects which may be encountered with various types of a.d.c. and d.a.c. are discussed, and the merits of different types of converter for high-quality sound are considered.