Abstract :
The paper describes a trial telephone exchange designed as a spacedivision system to be installed in the city of Munich. The switching arrays developed for the speech network have cross-points, each composed of three or four dry-reed contacts, which are switched directly by the magnetic fields of crossed coils. Each magnetic-field coupler, or switch, has 11 inlets and 220 outlets. The switching time is about 1 millisec. The switching network is controlled by electronic markers assigned to the individual switching stages. The connection is established digit by digit during the interdigital pauses. The markers need not be modified if changes have to be made in the telephone network. The operation of the markers and their working with the switching arrays of the speech network is controlled by programmes permanently incorporated in the circuit logic. Thus the exchange does not require any programme storage. All that is necessary are small registers, which, as buffer stores, are required to store only a single digit at a time. The operating principle of the magnetic switching array, the overall plan of the exchange, its incorporation in the local and long-distance dialling network and the operating principles of the markers are described.
