GB1289348A - - Google Patents

Abstract

1289348 Automatic exchange equipment STANDARD TELEPHONES & CABLES Ltd 18 Aug 1970 [28 Aug 1969] 43000/69 Heading H4K In a TDM telephone exchange system each digit of a wanted outsinks number is sent in the form of a five element code and is repeated at least once. Each element is sent as 8 bits and the received bits are put into counter BC with all 1 bits being put additionally into majority decision counter MDC. After the 8 bits representing one element of a code have been received in counter BC the output of counter MDC is stored in shift register CASR which is then incremented by the resetting pulse on BCO which also resets counters MDC and BC ready to receive the bits of the next element. Counter CAC is a five element counter which is incremented by the pulse on BCO so that after five elements have been received it is recognized, by the presence of an output from CAC, that a digit is now stored in CASR. The contents of CASR are shifted into store PCR so that register CASR can be filled with the next five elements received. The elements stored in CASR and PCR are compared in the 5 bit comparator COMP and, if identical, cause the digit to be inserted in the telephone exchange register when a code for an interdigital pause is received.