HANDS FREE TELECOMMUNICATIONS APPARATUS AND METHOD

摘要

In a hands free communications terminal apparatus, a loudspeaker and a microphone are permitted to be simultaneously active. A controller monitors signals in transmit and receive paths to direct operations of transversal filters to provide two echo canceler functions, one for the microphone and one for a telephone line so that most unwanted echo and feedback is removed, to prevent the howling and squealing sounds that commonly occur when the loudspeaker and the microphone are both active. Remaining echoes are removed by voice switching of loss between transmit and receive paths, wherein the amount of loss is determined in response characteristics of the telephone line and the operating environment of the terminal apparatus.