1
Susan C Kromenaker, James D Lefebvre, Charles P Binzel: Speakerphone for cellular telephones with howl prevention, detection, elimination and determination. Motorola, Rolland R Hackbart, May 7, 1991: US05014294 (30 worldwide citation)

A unique speakerphone for celluar telephones includes in the transmit audio path between microphone 112 and transmitter 118, a transmitter mute switch which disconnects the audio path to the transmitter from the microphone 112, and a transamit gain amplifier that is controlled to lower the feedback ...


2
Kromenaker Susan C, Binzel Charles P, Lefebvre James D: Haut-parleur de radiotelephone a dispositif de prevention, de detection et delimination du sifflement, Speakerphone for cellular telephones with howl prevention, detection, elimination and determination. Motorola, GOWLING LAFLEUR HENDERSON, August 2, 1991: CA2048650

A unique speakerphone for cellular telephonesincludes in the transmit audio path between microphone112 and transmitter 118, a transmitter mute switchwhich disconnects the audio path to the transmitterfrom the microphone 112, and a transmit gain amplifierthat is controlled to lower the feedback the m ...