Bell Telephone Laboratories

William L Aranguren

Rollin E Langseth

The present invention relates to method and apparatus for providing a communication arrangement between two or more independently operable microprocessor units (MPUs). Large amounts of data or data in block format are capable of being passed between MPUs via the present intercommunication channel with little handshaking between MPUs. In the present arrangement, a plurality of MPUs sequentially access, under the control of a synchronous clock, a common memory for random access to blocks of memory for writing data therein or for reading data previously written therein without the necessity for contention resolving means.

Multiple microprocessor intercommunication arrangement

The present invention relates to a small digital time-division switching arrangement capable of interfacing with a plurality of PCM communication lines on one side and a separate plurality of transmission channels on the other side. A first processor primarily tracks call progress by scanning signalling bits indicating on/off hook state changes and a second processor controls the action of a time slot interchanger which both assembles and disassembles channel data and telemetry messages and establishes and breaks down calls while connecting appropriate service circuits to the communication lines during the progress of a call. The processors are implemented with separate microprocessor chips and associated memory and the switching arrangement can simultaneously communicate with a variety of call originating circuits employing a wide variety of control signals.

Small digital time division switching arrangement

A receiver especially for use as a diversity combining receiver is adapted to recover a single signal from among a plurality of cochannel signals transmitted from a plurality of sources. When recovering signals from a plurality of sources, the various sources transmit signals having PSK modulation and having, in addition, pilot tag modulation uniquely associated with each source. The output from each of the diversity branches is combined and the combined output is mixed with the output signal generated by a free-running oscillator to produce a loop signal uniquely identified by one selected tag. The processing is arranged so that when this loop signal is mixed with each branch input, the resulting sideband product of the loop signal and the one received signal having the selected tag contains a distinctive cophasing phase angle but is stripped of its PSK information and tagging modulation. However, the resulting sideband product of the loop signal and any unselected received signal contains some unremoved modulation or tagging and it is, therefore, distinguishable. Only the one modulation-free product derived from the received signal having the selected tag, is mixed with the total branch input and thus only the transmission having the selected tag contributes to the cophased combined output. The present arrangement provides a precise loop signal, and the loop will remain locked despite slight variations of either one or both of the input signal frequency or the injection frequency generated by the free-running local oscillator.

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Sayreville, NJ, United States of America

William L Aranguren