ITU-R - International Telecommunication Union/ITU Radiocommunication Sector
Scope
"Introduction This Report contains the preliminary results of a comparison of the multiplexing methods that can be used for the emission of several channels carrying digital sound and possibly other information@ either with or without an associated analogue television picture emission@ for new broadcasting applications. In this context this Report deals primarily with the use of the satellite??broadcasting channel@ although some of the information is also valid for terrestrial broadcasting channels. The study of multiplexing methods for several audio signals and data must take due account of the two main methods of multiplexing the complete digital signal with the video@ which are: ?? ""interrupted""@ i.e. digits in the .line??blanking interval; ?? ""uninterrupted""@ i.e. digits on a sub-carrier. In the latter case@ for sound only in the absence of a video signal@ the digits can be on a carrier@ but this is - only a special case of the sub??carrier. In the case of ""interrupted""@ the case of digits in the field??blanking interval is not considered in this Report. Regarding the multiplexing of the various digital sound and data signals@ two basic techniques are envisaged here: ""continuous"" multiplexing and ""packet"" multiplexing; the advantages and disadvantages inherent in the principle of each system have been investigated for both cases mentioned above@ i.e. the interrupted and uninterrupted multiplex. Further studies will be needed to optimise these types of systems."