Patent EP-0144076-A3 (EP)
Title: Integrated services digital transmission network
IPC: H04M11/06
Filed: 1984-11-29
Abstract: 1. Service-integrated digital communications transmission system for the transmission of a number of wide band main channels (K1-K3, Fig. 1) as well as a wide band additional channel (K4, Fig. 2) from an exchange (Z, Fig. 1) to the subscribers (TIn1 -TInm , Fig. 1), wherein a video signal (TV1 -TVn , Fig. 2) is transmissible in each wide band main channel (K1-K3), wherein one of the video signals (TVn , Fig. 2) is an image telephone signal (Ban) delivered by an image telephone coupling field (BIFE, Fig. 1), wherein an additional channel multiplexer (Z-Mux, Fig. 2) for each subscriber (TIn1 -TInm ) is furthermore provided in the exchange (Z) and forms the wide band additional channel (K4) from a sound multiplex signal (ST) as well as narrow band signals (SDan ), wherein the sound multiplex signal is formed from several sound radio programs in a central sound preparation (Ton-A, Fig. 1), wherein a respective wide band return channel (R, Fig. 2) is furthermore transmitted from each of the subscribers (TIn1 -TInm ) and comprises an image telephone return signal (Bab , Fig. 2) and narrow band return signals (SDab , Fig. 2), wherein a return channel demultiplexer (R-Dem, Fig. 2) for each subscriber (TIn1 -TInm ) is provided in the exchange and resolves the wide band return channel (R) into the image telephone return signal (Bab ) and the narrow band return signals (SDab ), characterised thereby, that the sound preparation (Ton-A) is so structured that it delivers the sound multiplex signal and synchronising signals (Syn) with a frame build-up, in which empty places ares provided for the insertion of the narrow band signals (SDan ) by the additional channel multiplexer (Z-Mux), that the additional channel multiplexer (Z-Mux) and the return channel demultiplexer (R-Dem) are built up alike and each consist of a multiplexer (Mux, Fig. 2) and a demultiplexer (Demux, Fig. 2), that each multiplexer (Mux) displays an output (Am , Fig. 2) as well as a first input (E1 , Fig. 2) and a second input (E1 , Fig. 2) and a second input (E2 , Fig. 2), that each demultiplexer (Demux) displays a first output (A1 , Fig. 2) and a second output (A2 , Fig. 2) as well as an input (ED , Fig. 2), that the first output (A1 ) of each demultiplexer (Demux) is connected with the first input (E1 ) of the associated multiplexer (Mux), that each demultiplexer (Demux) is so constructed that a digital signal applied at its input (ED ) appears unchanged at its first output (A1 ) and the signal to be branched off appears at its second output (A2 ), that each multiplexer (Mux) is so constructed that a digital signal applied at its first input (E1 ) is delivered at equal bit rate at its output (AM ), wherein the bits associated with the signal present at the second input (E2 ) are written over in correspondence with this signal, that in the additional channel multiplexer (Z-Mux), the sound multiplex signal (ST) is fed to the input (ED ) of the demultiplexer (Demux), the narrow band signals (SDan ) are fed to the second input (E2 ) of the multiplexer (Mux) and the wide band additional channel (K4) is taken off at the output (AM ) of the multiplexer (Mux), that in the return channel demultiplexer (R-Dem), the input (ED ) of the demultiplexer (Demux) is acted on by the wide band return channel (R) and the second input (E2 ) of the multiplexer (Mux) is acted on by No-signals, the narrow band return signals (SDab ) are taken off at the second output (A2 ) of the demultiplexer (Demux) and the image telephone return signal (Bab ) is taken off at the output (AM ) of the multiplexer (Mux).