Cryptography – Cryptanalysis
Patent
1995-05-23
1997-07-29
Gregory, Bernarr E.
Cryptography
Cryptanalysis
381 711, 381 731, 381 941, 375710, 375229, 375232, 375346, 375350, H04K 102, H04L 2730, G10K 1116
Patent
active
RE0355747
ABSTRACT:
A communication device, an apparatus, and a method for acoustic echo cancellation which makes use of a pseudonoise signal. An audio mixer adds the pseudonoise signal to an input signal received from another communication device to produce a first composite signal. An audio system converts the first composite signal to sound in an at least partially enclosed space. The at least partially enclosed space produces an acoustical echo in response. The audio system then converts the acoustical echo and other sounds in the at least partially enclosed space to a second composite signal. A signal processor cross-correlates the second composite signal with the pseudonoise signal to produce an estimate of the overall impulse response of the combined system formed by the at least partially enclosed space and the audio system. The processor then convolves the first composite signal with the impulse response estimate to produce an echo estimation signal. The echo estimation signal is an estimate of the component of the second composite signal which corresponds to the acoustical echo. The processor then subtracts the echo estimation signal from the second composite signal to produce an output signal.
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Doherty John F.
Russell Steve F.
Gregory Bernarr E.
Iowa State University & Research Foundation, Inc.
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