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US4623980A
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Method of processing electrical signals by means of Fourier transformations
Assignee: Tekade Felten and Guilleaume Fernmeldeanlagen GmbH
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Filing: 1985-03-08
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Granted: 1986-11-18
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Expires: 2005-03-08
Abstract
Abstract In order to upgrade input signals for further processing, one or more of the input signals is split up by a decimating technique into spectral component signals which are processed according to the desired purpose and recombined by means of an interpolation technique into an output signal. In this manner a digital filtering device can be selectively employed for achieving an arbitrary combination of simultaneous filtering, signal improvement, echo or feedback compensation, or signal masking of the input signals.
Inventors
- 👤 Peter Vary
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:06
CPC Classifications
H; H04; H04K; H04K1/00; H04K1/04; G; G10; G10L; G10L21/00; G10L21/02; H03; H03H; H03H17/00; H03H17/02; H03H17/0283; H03H17/0286; H03H17/0288; H04B; H04B1/00; H04B1/66; H04B1/667; H04B3/00; H04B3/02; H04B3/20; H04B3/21; G10L25/00; G10L25/03; G10L25/18
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
164 words
A method of cancelling echo in speech frequency electrical signals by a digital filtering arrangement, comprising the steps of applying at least one input signal u to a polyphase network to produce intermediate output signals V v , subjecting the intermediate output signals to a discrete Fourier transformation to produce spectral partial signals V v having separated real and imaginary components, processing the spectral partial signals V v by an adaptive level control to produce at outputs of the digital filtering arrangement complex time signals W v which meet the equation W.sub.v (ρ)=c.sub.v (ρ)·V.sub.v (ρ), wherein c v is a level factor determined during speech pauses as a function of momentary signal expectation values E1 and E2 and of the spectral partial signals V v according to the equation ##EQU10## where N v are interference components, and interpolating the processed signals W v in an output signal S, the interpolation step including inverse, discrete Fourier transformation and inverse polyphase filtering in a polyphase network.
Claim 2
Independent Claim
164 words
A method of cancelling echo in speech frequency electrical signals by a digital filtering arrangement, comprising the steps of applying at least one input signal u to a polyphase network to produce intermediate output signals V v , subjecting the intermediate output signals to a discrete Fourier transformation to produce spectral partial signals V v having separated real and imaginary components, processing the spectral partial signals V v by an adaptive level control to produce at outputs of the digital filtering arrangement complex time signals W v which meet the equation W.sub.v (ρ)=c.sub.v (ρ)·V.sub.v (ρ), wherein c v is a level factor determined during speech pauses as a function of momentary signal expectation values E1 and E2 and of the spectral partial signals V v according to the equation ##EQU10## where N v are interference components, and interpolating the processed signals W v in an output signal S, the interpolation step including inverse, discrete Fourier transformation and inverse polyphase filtering in a polyphase network.
Claim 3
Dependent Claim
27 words
A method as defined in claim 1 wherein momentary expectation values of spectral partial signals V v are used for determining said level factor C v (ρ).
Claim 4
Dependent Claim
28 words
A method as defined in claim 1 wherein at least one input signal u is used as a reference signal for determining said level factor c v (ρ).
Claim 5
Dependent Claim
33 words
A method as defined in claim 1 wherein for the purpose of speech signal masking, conjugate bands of said complex time signals W v are interchanged and simultaneously subjected to said interpolation step.
Claim 6
Dependent Claim
28 words
A method as defined in claim 1 wherein for the purpose of speech signal masking, signs of imaginary components of said complex time signals W v are reversed.
Claim 7
Dependent Claim
53 words
A method as defined in claim 1 wherein the spectral partial signals V v are processed by any combination of an adaptive level control and/or filtering and/or echo cancellation to produce the processed signals W v suitable for filtering, signal improvement, echo cancellation and/or signal masking of said at least one input signal.
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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) | 1989-11-17 | 1990-05-19 | 1990-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-11-17 | 1994-05-19 | 1994-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-11-17 | 1998-05-19 | 1998-11-18 | $7700.00 | Window Closed / Lapsed |