Standards for the transmission of several sound signals in one television channel in terrestrial or satellite broadcasting including high-definition and enhanced definition television systems
The ITU Radiocommunication Assembly considering a) that there is a requirement to transmit more than one sound signal including stereophony with a television picture; b) that within a television channel as used in present systems several sound channels could be accommodated; c) that the use of some of these additional possibilities could necessitate changes to the present television standards; d) that changes affecting existing transmissions can only be introduced if compatibility with existing receivers, at least during a sufficiently long transition period, is retained; e) that a prerequisite of a new system is that the sound signals should serve at least the same coverage area as the vision signal; f) that a new system could also provide for the transmission of sound programmes, independent from the picture, or in place of a television picture; g) that the technical quality of the sound transmission can be improved; h) that the improvements in picture quality associated with high-definition and enhanced definition television may warrant examination of the sound system needed to keep in step with the higher level of realism available in the picture.