GB1510015A - Digital data signal transmission systems - Google Patents

Abstract

1510015 Plesiochronous network, telegraphy SIEMENS AG 11 April 1975 [26 April 1974] 14935/75 Headings H4M and H4P] In a plesiochronous data transmission network the exchanges form timing islands, at least one of which comprises a plurality of exchanges operating in synchronism. Each timing island works at its own data bit-rate determined by a corresponding clock source, data from each exchange being transmitted at the exchange's data bit-rate, the latter being converted, at the input of the destination exchange if of a different timing island, to the data bit-rate prevailing there. As shown, data at bit-rates T2, T3, T5 transmitted by exchanges (ZMV2-ZMV5), Fig. 1 (not shown), of other timing islands, passes via multiplex units M, known data bit-rate compensation units G, and optionally via one bit buffer stores L, to the input of exchange ZMV1 having the data bit-rate T 1 . Data from the latter exchange's own timing island may be received at multiplex unit M1, links to and from subscribers directly connected to the exchange, being via units due. Data for transmission from the exchange passes, at the bit-rate T, to buffer stores L, and hence is multiplexed out by units M, M 1 , the rate T being the same as T 1 , but delayed by unit t. Fig. 2 (not shown) displays a simpler arrangement without timing signal delay, or buffer stores. A disadvantageous arrangement is discussed in relation to Fig. 3 (not shown), wherein the data bit-rate of incoming data is converted to the data bit-rate of the particular exchange at the output thereof.