Rauland-borg Corporation

Carl P Rau

James E Dahlquist

Peter C Holtermann

A multi-link communication system includes a number of stations and interconnecting audio links under the control of a central computer. Each station is addressable by the computer for connecting selected stations to a selected audio link for establishing audio communication between stations. Each station has at least one corresponding access circuit for establishing an audio connection to a selected or preassigned link, and the connection is maintained by a corresponding memory circuit that is addressable by the computer. A group of output lines from the computer are used as select inputs to an analog multiplexer connecting a bidirectional control line to the selected access circuit for connecting or disconnecting the corresponding station and also for receiving connect or disconnect requests from the corresponding station. In a particular embodiment, the stations include multi-link dial and dialless telephones, single-link dialless telephones, and intercom speakers in an automatic private branch exchange. Latching relays provide audio connections for speakers and dialless single-link phones, and unbalanced analog transmission gates provide audio connections for multi-link phones. The capabilities of each station are encoded as predefined attributes stored in electrically alterable memory, and the attributes of a selected station are user-programmable via the touch-tone dial of an administrative telephone. Standard and priority call-ins from dialless phones and intercom speakers are identified on numeric or graphic displays interconnected to the computer via a shielded wire or shielded balanced pair conveying a pulse-width modulated binary signal.

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Mount Prospect, IL, United States of America

Carl P Rau