Telephonic communications – Substation or terminal circuitry – For loudspeaking terminal
Patent
1985-02-26
1987-09-22
Rubinson, Gene Z.
Telephonic communications
Substation or terminal circuitry
For loudspeaking terminal
381113, 333 17R, 333 14, H04M 908, H04R 306
Patent
active
046960325
ABSTRACT:
A voice switched gain system is disclosed for loudspeaking telephone and hearing aid applications involving electret microphones. A voice switched gain circuit comprises an audio pre-conditioning circuit for providing a conditioned audio input referenced to an unconditioned audio input to a compandor circuit. A linear gain level reference generator circuit generates a level for comparison with the audio input level. A decision circuit then controls the compandor operation based on the result of the comparison. The decision circuit either maintains the audio output of the compandor in a compressed state or expands the audio input signal to a higher level expanded state for transmission. Two such circuits are provided in a loudspeaking telephone system, one circuit for maintaining a preemptive near end control through appropriate timing of the dual decision process. Far end control is provided by the other voice switched gain circuit. Altogether three states of operation are possible, an idle state, near end control and far end control. In one embodiment, a dial preemption circuit is disclosed so that during dialing the loudspeaking telephone only broadcasts dialing signals.
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Markline catalog, P.O. Box C-5, Belmont, MA, 02178, Spring 1985, p. 3.
Signetics Analog Data, Jun., 1983, pp. 5-3 through 5-9.
Ahmed Adel A.
Jackson Thomas H.
Rubinson Gene Z.
Siemens Corporate Research & Support, Inc.
Vaas R.
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