Patent ID: 7130413

Claim:
A duplex portable handset speakerphone, comprising: a microprocessor; a hands-free receive register coupled to the microprocessor; a hands-free transmit register coupled to the microprocessor; a memory circuit having an algorithm executable by the microprocessor for operating the speakerphone; a first analog-to-digital converter coupled to the hands-free receive register; a second analog-to-digital converter coupled to the hands-free transmit register; a first programmable digital attenuator in a speech path and coupled to the microprocessor and to a speaker; a second programmable digital attenuator in another speech path and coupled to the microprocessor and to a microphone; wherein the microprocessor alternately receives speech signals in the respective speech paths and determines peak volume levels in both speech paths and adjusts gain levels in the speech paths in response to the peak volume levels and is further adapted to operate in a plurality of full duplex substates, each substate defining a respective relationship between respective gains of the first and second speech paths.