A control circuit for a speakerphone circuit which utilizes an event driven circuit to determine the appropriate gain for the receive and transmit channels is provided. Detectors monitor the relative magnitudes of the signal in the transmit and receive channels. Separate signal-to-noise detectors determine...http://www.google.fr/patents/US5544242?utm_source=gb-gplus-shareBrevet US5544242 - Speakerphone with event driven control circuit
