Telephonic communications – Substation or terminal circuitry – For loudspeaking terminal
Patent
1995-02-24
1997-10-21
Zele, Krista M.
Telephonic communications
Substation or terminal circuitry
For loudspeaking terminal
379406, 379410, 381 59, 381103, H04M 908, H04R 2900
Patent
active
056804504
ABSTRACT:
An echo canceling loudspeaker telephone includes a loudspeaker which produces a sound pressure wave in response to an input signal which is applied to an audio input thereof. This sound pressure wave includes a desired linear component which is a linear function of the input signal, and an undesired non-linear component which is a non-linear function of the input signal, and the sound pressure wave is transmitted along an acoustic path. A microphone is positioned in the acoustic path and converts the sound pressure wave into an output signal. An echo filter is responsive to the input signal and generates an estimated echo signal. This echo filter includes a loudspeaker model which generates an estimate of the sound pressure wave including an estimate of the linear component and an estimate of the non-linear component. This echo filter also includes an acoustic path model which generates an estimate of the acoustic path from the loudspeaker to the microphone. In addition, a subtractor subtracts the estimated echo signal from the output signal thereby reducing an echo portion of said sound signal.
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Dent Paul W.
Solve Torbjorn W.
Ericsson Inc.
Kumar Devendra
Zele Krista M.
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