Stromberg-Carlson Corporation

Other

Stanley L Russell

Uwe A Pommerening

Charles J Breidenstein

William A Oswald

Klaus Gueldenpfennig

Barry Slingsby

Patrick M Kelly

Ronald W Christain

Julian W West

Karam V Narula

A digital private automatic branch exchange provides a plurality of ports which may comprise line trunks or operator circuits, the ports being grouped with each group being controlled by an individual microprocessor circuit which performs all real time control over the ports. Voice communication between ports is effected by time division multiplex in connection with a digital switch system forming part of a common control which is controlled by a central processing unit responsive to the microprocessors in each port group for assigning time slots to each interconnection channel. Isolation between the central processing unit and the rest of the system is provided by a peripheral bus to which the common control units and port groups are connected, which peripheral bus is connected to the CPU bus by way of an interface circuit, permitting the system to operate with various types of central processing units without redesign of the peripheral units. A conference circuit is also provided for making available a range of conference sizes by combining the available lines to the conference circuit into groups of a predetermined size which may be expanded by combining groups to form conferences of larger or intermediate size.

Digital private branch exchange

A private telephone network that includes multifunction telephones. Multifunction telephones are connected to common equipment by a voice signal path and a data signal path. Supervisory information passes over the data signal path in the form of polled messages that are sent from the common equipment to the telephone. Sense information is received by the common equipment from the telephone. The transmission is by frequency modulation, such as frequency-shift-keying modulation, techniques. At the multifunction telephone, a programmed microcomputer contains three blocks of instructions for enabling the microcomputer to perform background operations, to respond to the initial receipt of a message, and to thereafter transmit and decode the message. Further, in response to the decoding block of instructions, that are provided on a fixed time basis, the microcomputer is able to transmit frequency-shift-keyed signals without the need for a separate frequency-shift-keyed transmitter.

Telephone network including common equipment with message information

A digital interface especially useful for isolating a speedily responsive circuit from the effects of transients at its input such as may be caused, for example, by contact bounce in a relay. The circuit includes a monostable multivibrator connected to be set in response to changes of alternately opposite polarity of the input signal and having a characteristic period equal to a predetermined fraction of the normal minimum interval between intended changes of the input signal. The output of the multivibrator is used to drive a flip-flop at the end of the characteristic period to produce the desired output signal. Thus, the circuit is non-responsive to relatively rapid alternations of the input signal immediately following a change of its condition, yet responds reliably when the input signal changes state and remains stable in its new state for a time exceeding the characteristic period of the multivibrator.

Noise rejection circuit

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West Webster, NY, United States of America

Stanley L Russell