At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Joseph H Havens

Milton L Embree

David A Snyder

Rouben Toumani

Tom D Arntsen

William T Jones

A transceiver is adapted for communication with another transceiver over a common channel by a technique that allows both transceivers to be identical in manufacture and use. The technique avoids designating one transceiver the 'master' and the other the 'slave', by relying on random time differences between transmissions during a start-up period that initially establishes communications. The transmissions are typically in multi-bit packets. An example using an optical transceiver having a light emitting diode used for both optical transmission and optical detection is given, wherein the channel is an optical fiber.

Peer relationship transceiver

An origination scan circuit for detecting circuit closure state in a loop circuit has a much lower impedance than does the typical loop circuit. Its source impedance is split into separate resistive parts for connecting opposite terminals of an office battery to the tip and ring leads of the loop. Currents in the separate resistive parts are sensed and summed for comparison against a threshold current to indicate whether or not a subscriber station on the loop is off hook. Threshold current magnitude is variable to accommodate loop start and ground start applications. When the off-hook state is detected, the origination scan circuit is disabled by switching open the resistive part connections, and loop current is thereafter provided by other suitable means. Automatic current limiting arrangements are included for converting the switching functions to high impedance circuit elements.

Low resistance origination scan circuit

Growing community of inventors

Reading, PA, United States of America

Joseph H Havens