GB1188284A - Improvements in Signalling Systems - Google Patents

Abstract

1,188,284. Automatic telephone systems. PLESSEY BTR Ltd. 19 May, 1967 [28 March, 1966], No. 13576/66. Heading H4K. PCM channels of incoming t.d.m. highways are switched to channels of outgoing t.d.m. highways by way of alternately employed storage arrangements worked in parallel. As shown in Fig. 1 the storage arrangements comprise matrices M11, M12, in parallel with matrices M21, M22. The matrices M11 and M21 each have a storage row for each incoming highway such as 10; PCM data in one multiplex cycle being recorded on one matrix and that in the next cycle being recorded on the other matrix and so on. The matrices M12 and M22 each have a storage row for each outgoing highway, such as 11; the matrices being read out to the highways in alternate cycles. While M11 receives and stores PCM data, M21, which contains a record of the data received in the preceding multiplex cycle, is selectively read out to matrix M22 so as to re-arrange the data pending its transmission on the appropriate channels of the outgoing highways in the following cycle. Also at this time the data in M12, which is the re-arranged data from M11 of two multiplex cycles back, is read out to the outgoing highways. A similar arrangement is necessary for transmission in the reverse direction. Instead of being gated in alternate cycles to metrices M11, M21, the incoming highways may be gated in alternate time slots to the equivalent of single columns of such matrices. While the data received by one such smaller store in the preceding time slot is being forwarded to the off-line one of the matrices M12, M22, the other stores the incoming codes in the current time slot. If, on the other hand, the full matrices are preserved for M11, M21, the outgoing matrices M12, M22, may be replaced by smaller stores worked in alternate time slots. The storage arrangements may be magnetic and of the woven plated wire type. Spare matrices may be provided to automatically replace faulty ones.