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Conference Circuit

IP.com Disclosure Number: IPCOM000094264D
Original Publication Date: 1966-Aug-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Garcia, J: AUTHOR [+2]

Abstract

The conference circuit is for use within communication systems and allows five audio terminals to communicate with each other.

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Conference Circuit

The conference circuit is for use within communication systems and allows five audio terminals to communicate with each other.

Interconnections between five terminals are established by five bi-directional amplifiers analogous to two-wire repeaters. Like the latter, these circuits comprise two balanced transformers and two amplifiers, one for direct and the other for reverse transmission. Input balanced transformers TE cannot be accurately matched because they can be connected to terminals through lines of different lengths. On the contrary, for output balanced transformers TS, the output impedance is accurately known and matching can be very good.

Assume terminal A1 is sending. The signal is transmitted through junctor J1 to input transformer TE1. If matching is good and transformer losses are low, one-half of the signal is applied to amplifier AD1 input and the other half is dissipated through resistor R's. After amplification by AD1, a first part of the signal is dissipated through resistor Rs and a second part through matching impedance Ze. If matching is good, no signal is applied to the amplifier AR1 input.

A third part of the signal is applied to the upper half-winding of transformer TS1 and is transmitted to transformers TS2, TS3, TS4, and TS5. The output power of TS1 is equally shared between the other four transformers. Each of these transformers further transmits the signal to terminals A2, A3, A4, and A5 through amplifiers AR2, AR3,...