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A LOW COST ALTERNATIVE FOR TELEPHONE INTERCONNECT WITH A PORTABLE RADIO

IP.com Disclosure Number: IPCOM000006076D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2001-Nov-30
Document File: 2 page(s) / 97K

Publishing Venue

Motorola

Related People

Tracy Fulghum: AUTHOR

Abstract

Previously, complicated repeater/base hardware was required to make an interconnection or patch to the telephone system from a remote, half-duplex portable radio. This situation exposed the need for a simple, inexpensive method by which the small scale customer, the one with two or three talk-and-listen units, can make or receive a telephone call remotely using his radio with a DTMF touch pad.

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MOTOROLA INC. Technical Developments Volume 12 April 1991

A LOW COST ALTERNATIVE FOR TELEPHONE INTERCONNECT WITH A PORTABLE RADIO

by Tracy Fulghum

   Previously, complicated repeater/base hardware was required to make an interconnection or patch to the telephone system from a remote, half-duplex portable radio. This situation exposed the need for a simple, inexpensive method by which the small scale customer, the one with two or three talk-and-listen units, can make or receive a telephone call remotely using his radio with a DTMF touch pad.

  One method involves a device which acoustically couples the receive and transmit audio of a local portable radio to the transmit and receive portion of a standard telephone handset (B) by means of modem type cups. The physical connection of the cups to the local telephone (B) would be made by an intermediary at the request of whoever was making the call, the user at the remote telephone (A), or the user at the remote radio (C). Besides coupling the audio between the telephone system and the local portable radio, the

phone patch device allows the person at the other end of the telephone line to control the push-to-talk (PTT) or transmit function of the local radio (B). The phone patch device either senses a specific DTMF tone pressed by the remote telephone user (A) to key the local radio (B) to transmit, or it can use VOX circuitry with sufficient hysteresis to simply detect the presence of the remote telephone user's voice and key the local radio (B). The latter case would take into account the side tone present due to the receive audio of the local radio (B). This device would require minimal circuitry and ride "piggy-back" of the local radio (B), connected to...