US5327496A
Expired / Lapsed
US
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Communication device, apparatus, and method utilizing pseudonoise signal for acoustical echo cancellation
Assignee: Iowa State University Research Foundation Inc
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Filing: 1993-06-30
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Granted: 1994-07-05
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Expires: 2013-06-30
Abstract
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.
Inventors
- 👤 Steve F. Russell
- 👤 John F. Doherty
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 01:43
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/08; H04M9/082; G; G10; G10K; G10K2210/00; G10K2210/10; G10K2210/108; G10K2210/30; G10K2210/301; G10K2210/3018; G10K2210/3023; G10K2210/30232; G10K2210/3049; G10K2210/50; G10K2210/505; G10K2210/512
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
204 words
A communication device comprising: a signal generator for generating a pseudonoise signal; an audio mixer responsive to an input audio signal and said pseudonoise signal for combining said input audio signal with said pseudonoise signal to produce a first composite signal; an audio system responsive to said first composite signal for converting said first composite signal to sound in an at least partially enclosed space, said at least partially enclosed space producing an acoustical echo in response, said audio system also for converting said acoustical echo and other sounds in said at least partially enclosed space to a second composite signal, said second composite signal including an echo component corresponding to said acoustical echo, said at least partially enclosed space and said audio system together forming a combined system having an overall impulse response; means responsive to said second composite signal and said pseudonoise signal for generating a first estimate of said overall impulse response; means responsive to said first composite signal and said first estimate for generating an echo estimation signal corresponding to an estimate of said echo component of said second composite signal; and means for subtracting said echo estimation signal from said second composite signal to produce an output audio signal.
Claim 2
Dependent Claim
204 words
A communication device comprising: a signal generator for generating a pseudonoise signal; an audio mixer responsive to an input audio signal and said pseudonoise signal for combining said input audio signal with said pseudonoise signal to produce a first composite signal; an audio system responsive to said first composite signal for converting said first composite signal to sound in an at least partially enclosed space, said at least partially enclosed space producing an acoustical echo in response, said audio system also for converting said acoustical echo and other sounds in said at least partially enclosed space to a second composite signal, said second composite signal including an echo component corresponding to said acoustical echo, said at least partially enclosed space and said audio system together forming a combined system having an overall impulse response; means responsive to said second composite signal and said pseudonoise signal for generating a first estimate of said overall impulse response; means responsive to said first composite signal and said first estimate for generating an echo estimation signal corresponding to an estimate of said echo component of said second composite signal; and means for subtracting said echo estimation signal from said second composite signal to produce an output audio signal.
Claim 3
Dependent Claim
25 words
The device of claim 1 wherein said means for generating said first estimate includes means for cross-correlating said second composite signal and said psneudonoise signal.
Claim 4
Dependent Claim
26 words
The device of claim 2 wherein said means for generating said echo estimation signal includes means for convolving said first composite signal with said first estimate.
Claim 5
Dependent Claim
68 words
The device of claim 1 further comprising: means responsive to said output audio signal and said pseudonoise signal for computing a decision value; wherein said means for generating said echo estimation signal includes first means responsive to said decision value and to said first estimate for producing said echo estimation signal based on said first estimate only when said decision value does not exceed a predefined threshold value.
Claim 6
Dependent Claim
70 words
The device of claim 4 further comprising: means responsive to said first composite signal and said output signal for generating a second estimate of said overall impulse response; wherein said means for generating said echo estimation signal includes second means responsive to said decision value and to said second estimate for producing said echo estimation signal based on said second estimate only when said decision value exceeds said threshold value.
Claim 7
Dependent Claim
56 words
The device of claim 5 wherein: said means for generating said first estimate includes means for cross-correlating said second composite signal and said pseudonoise signal; and said first means includes means for convolving said first composite signal with said first estimate; said second means includes means for convolving said first composite signal with said second estimate.
Claim 8
Dependent Claim
214 words
An acoustical echo cancellation apparatus for use with an audio system, said audio system responsive to a first composite signal for converting said first composite signal to sound in an at least partially enclosed space, said at least partially enclosed space producing an acoustical echo in response, said audio system also for converting said acoustical echo and other sounds in said at least partially enclosed space to a second composite signal, said second composite signal including an echo component corresponding to said acoustical echo, said at least partially enclosed space and said audio system together forming a combined system having an overall impulse response, said apparatus comprising: a signal generator for generating a pseudonoise signal; an audio mixer responsive to an input audio signal and said psneudonoise signal for combining said input audio signal with said pseudonoise signal to produce said first composite signal; means responsive to said second composite signal and said pseudonoise signal for generating a first estimate of said overall impulse response; means responsive to said first composite signal and said first estimate for generating an echo estimation signal corresponding to an estimate of said echo component of said second composite signal; and means for subtracting said echo estimation signal from said second composite signal to produce said output audio signal.
Claim 9
Dependent Claim
214 words
An acoustical echo cancellation apparatus for use with an audio system, said audio system responsive to a first composite signal for converting said first composite signal to sound in an at least partially enclosed space, said at least partially enclosed space producing an acoustical echo in response, said audio system also for converting said acoustical echo and other sounds in said at least partially enclosed space to a second composite signal, said second composite signal including an echo component corresponding to said acoustical echo, said at least partially enclosed space and said audio system together forming a combined system having an overall impulse response, said apparatus comprising: a signal generator for generating a pseudonoise signal; an audio mixer responsive to an input audio signal and said psneudonoise signal for combining said input audio signal with said pseudonoise signal to produce said first composite signal; means responsive to said second composite signal and said pseudonoise signal for generating a first estimate of said overall impulse response; means responsive to said first composite signal and said first estimate for generating an echo estimation signal corresponding to an estimate of said echo component of said second composite signal; and means for subtracting said echo estimation signal from said second composite signal to produce said output audio signal.
Claim 10
Dependent Claim
27 words
The apparatus of claim 7 wherein said means for generating said first estimate cross-correlates said second composite signal and said pseudonoise signal for generating said first estimate.
Claim 11
Dependent Claim
26 words
The apparatus of claim 8 wherein said means for generating said echo estimation signal includes means for convolving said first composite signal with said first estimate.
Claim 12
Dependent Claim
68 words
The apparatus of claim 7 further comprising: means responsive to said output audio signal and said pseudonoise signal for computing a decision value; wherein said means for generating said echo estimation signal includes first means responsive to said decision value and to said first estimate for producing said echo estimation signal based on said first estimate only when said decision value does not exceed a predefined threshold value.
Claim 13
Dependent Claim
21 words
The apparatus of claim 10 wherein said first means includes means for convolving said first composite signal with said first estimate.
Claim 14
Dependent Claim
25 words
The apparatus of claim 11 wherein said means for generating said first estimate includes means for cross-correlating said second composite signal and said pseudonoise signal.
Claim 15
Dependent Claim
70 words
The apparatus of claim 10 further comprising: means responsive to said first composite signal and said output signal for generating a second estimate of said overall impulse response; wherein said means for generating said echo estimation signal includes second means responsive to said decision value and to said second estimate for producing said echo estimation signal based on said second estimate only when said decision value exceeds said threshold value.
Claim 16
Dependent Claim
21 words
The apparatus of claim 13 wherein said second means includes means for convolving said first composite signal with said second estimate.
Claim 17
Dependent Claim
41 words
The apparatus of claim 14 wherein: said means for generating said first estimate includes means for cross-correlating said second composite signal and said psnudonoise signal; and said first means includes means for convolving said first composite signal with said first estimate.
Claim 18
Independent Claim
191 words
A method of acoustical echo cancellation for use with an audio system, said audio system responsive to a first composite signal for converting said first composite signal to sound in an at least partially enclosed space, said at least partially enclosed space producing an acoustical echo in response, said audio system also for converting said acoustical echo and other sounds in said at least partially enclosed space to a second composite signal, said second composite signal including an echo component corresponding to said acoustical echo, said at least partially enclosed space and said audio system together forming a combined system having an overall characteristic impulse response, said method comprising the steps of: generating a pseudonoise signal; combining an input audio signal with said pseudonoise signal to form said first composite signal; generating a first estimate of said overall impulse response in response to said second composite signal and said pseudonoise signal; generating an echo estimation signal corresponding to an estimate of said echo component in response to said first composite signal and said first estimate; and subtracting said echo estimation signal from said second composite signal to produce an output signal.
Claim 19
Independent Claim
191 words
A method of acoustical echo cancellation for use with an audio system, said audio system responsive to a first composite signal for converting said first composite signal to sound in an at least partially enclosed space, said at least partially enclosed space producing an acoustical echo in response, said audio system also for converting said acoustical echo and other sounds in said at least partially enclosed space to a second composite signal, said second composite signal including an echo component corresponding to said acoustical echo, said at least partially enclosed space and said audio system together forming a combined system having an overall characteristic impulse response, said method comprising the steps of: generating a pseudonoise signal; combining an input audio signal with said pseudonoise signal to form said first composite signal; generating a first estimate of said overall impulse response in response to said second composite signal and said pseudonoise signal; generating an echo estimation signal corresponding to an estimate of said echo component in response to said first composite signal and said first estimate; and subtracting said echo estimation signal from said second composite signal to produce an output signal.
Claim 20
Dependent Claim
27 words
The method of claim 16 wherein said step of generating said first estimate includes the step of cross-correlating said second composite signal and said pseudorandom noise signal.
Claim 21
Dependent Claim
59 words
The method of claim 17 further comprising the steps of: computing a decision value in response to said output signal and said pseudonoise signal; wherein said step of generating said echo estimation signal includes the step of producing said echo estimation signal based on said first estimate only when said decision value does not exceed a predefined threshold value.
Claim 22
Dependent Claim
61 words
The method of claim 18 further comprising the step of: generating a second estimate of said impulse response in response to said first composite signal and said output signal; wherein said step of generating said echo estimation signal includes the step of producing said echo estimation signal based on said second estimate only when said decision value exceeds said threshold value.
Claim 23
Dependent Claim
32 words
The method of claim 18 wherein said step of producing said echo estimation signal based on said first estimate includes the step of convolving said first composite signal with said first estimate.
Claim 24
Dependent Claim
26 words
The method of claim 20 wherein said step of generating said first estimate includes the step of cross-correlating said second composite signal and said pseudonoise signal.
Claim 25
Dependent Claim
32 words
The method of claim 21 wherein said step of producing said echo estimation signal based on said second estimate includes the step of convolving said second composite signal with said second estimate.
Claim 26
Dependent Claim
53 words
The method of claim 22 wherein: said step of generating said first estimate includes the step of cross-correlating said second composite signal and said pseudonoise signal; and said step of producing said echo estimation signal based on said first estimate includes the step of convolving said first composite signal with said first estimate.
Claim 27
Dependent Claim
27 words
The method of claim 17 wherein said step of generating said echo estimation signal includes the step of convolving said first composite signal with said first estimate.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-07-04 | 1998-01-03 | 1998-07-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-07-04 | 2002-01-03 | 2002-07-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-07-04 | 2006-01-03 | 2006-07-05 | $7700.00 | Window Closed / Lapsed |