International Telephone and Telegraph Corporation

Arthur L Bandini

Stuart Barry Cohen

Robert H Haussmann

An asynchronous digital TDM multiplexer-demultiplexer combination at one communication terminal is capable of multiplexing N asynchronous input data signals having a random mixture of different bit rates into a transmitted synchronous data stream having a predetermined fixed data format and a given bit rate greater than the sum of the rates of the different rates and to demultiplex N asynchronous output data signals having the same random mixture of the different bit rates from a received synchronous data stream having the data format and the given bit rate, where N is an integer greater than 1. Each of the N channel printed circuit board plug-in receptacles, coupled to a different one of the N input data signals and a different one of N outputs each for a different one of the N output data signals, has plugged therein a selected one of no printed circuit boards, a digital data channel printed circuit board and an FSK channel printed circuit board to process a mixture of digital data signals, teletype signals and FSK signals in the N input data signals and the received data stream, with the mixture of signals being in any random order and mix and the digital channel printed circuit boards and the FSK channel printed circuit boards being plugged in the N receptacles in any random order and mix. The multiplexing and demultiplexing frame synchronization and automatic channel assignment is controlled by a programmable common controller so that the data bits of each of the N input data signals are distributed throughout the time slots of the transmitted and received data stream with equal spacing.

Asynchronous digital TDM multiplexer-demultiplexer combination

A common controller in the form of a programmed digital sequencer executes a series of instructions to control multiplexing-demultiplexing overhead channel format generation, frame synchronization stuff-destuff operation and automatic channel assignment in a digital TDM multiplexer-demultiplexer combination at one communication terminal to enable multiplexing N input data signals each having a predetermined bit rate into a transmitted synchronous data stream having a predetermined fixed data format and a given bit rate greater than the sum of the predetermined bit rates and to demultiplex N output data signals each having the predetermined bit rate from a received synchronous data stream having the data format and the given bit rate, where N is an integer greater than one. The disclosed common controller can be used with synchronous input and output data signals or for asynchronous input and output data signals wherein the asynchronous input and output data signals are distributed throughout the fixed data format in the time slots thereof evenly due to the automatic channel assignment. The programmed digital sequencer includes program memory means and support logic means coupled to the memory means to supply control signals in response to a plurality of digital codes present in the program memory means for multiplexing, demultiplexing, overhead channel format generation frame synchronization, stuff-destuff control and automatic channel assignment.

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Harrington Park, NJ, United States of America

Arthur L Bandini