GB1334092A - Transmission arrangements for binary coded information - Google Patents

Abstract

1334092 Digital transmission; stations connected to a common channel LICENTIA PATENT-VERWALTUNGS GmbH 8 Dec 1971 [9 Dec 1970] 57135/71 Heading H4P An addressing system for a number of stations permanently connected along a line or on a loop comprises means for adding the unique address of a code subscriber to signals already existing on the line to produce a binary coded summation signal which is extracted by a receiver. The addresses may comprise orthogonal functions and a calling station may add an address by modulo-2 addition. The system and frame synchronization must be provided by at least one clock generator emitting signals which may be non-changing or changing according to a determined pattern. With multiple sync. generators, mutual synchronization must be provided but on a loop a single sync. generator only is necessary with stand by facilities. An initial sync. sequence may be transmitted to all stations. In a loop arrangement a delay network may be incorporated to compensate for propagation delays and a single sync. generator with stand by facilities is employed. A double line system has directional monitoring so that messages are only sent in the required direction. For two directions of traffic with separate channels, circuit sync. generators G1, G2 are provided for each direction and separate transmitters S and receivers E (only one each shown) are employed. At the start of a message the direction of transmission is not known hence the initial call has to be made in both directions and similarly a receiver is receptive in both directions. Once communication has been established, only the channel necessary is used and signals are not passed to other parts of the system. Fig. 4 (not shown) illustrates a loop arrangement having a loop propagation delay compensator (LA) to prevent messages circulating endlessly. A called subscriber extracts them from the summation signal which extracts are normally stored for a duration of one frame or one circulation period. A plurality of loops and sets of double lines may be linked preferably through buffers which compensate for small phase shifts and frequency differences. The address may alternatively comprise quasiorthogonal functions whose cross correlation functions are approximately zero.