scope:

This section deals with methods of measurement for sound-programme analogue channels carried by radio-relay systems. The measurements are concerned only with the audio frequency band and are additional to those required on the radio-relay system baseband for television in Part 3, Section Three, for f.d.m. telephony in Part 3, Section Four and for mutual interference in Part 3, Section Five of this publication. In practice, the sound channels may be derived using analogue techniques, such as frequency-modulated sub-carriers or by time division multiplex using digital techniques.