Patent US5206854A successfully refreshed from Google Patents.
US5206854A
Expired / Lapsed
US
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Detecting loss of echo cancellation
Assignee: Nokia Bell Labs
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Filing: 1991-09-24
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Granted: 1993-04-27
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Expires: 2011-09-24
Abstract
Abstract In a full-duplex modem, correlation of an echo estimate signal with an echo-canceled signal is used to determine the presence or absence of a remote signal.
Inventors
- 👤 William L. Betts
- 👤 II Robert A. Day
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:59
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/20; H04B3/23; H04B3/237
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
61 words
A method comprising the steps of receiving a signal, subtracting an echo estimate signal from the received signal to provide an echo-canceled signal, correlating the echo estimate signal with the echo-canceled signal to provide a degree of correlation, and determining the absence of a remote signal by detecting the degree of correlation of the echo estimate signal with the echo-canceled signal.
Claim 2
Independent Claim
61 words
A method comprising the steps of receiving a signal, subtracting an echo estimate signal from the received signal to provide an echo-canceled signal, correlating the echo estimate signal with the echo-canceled signal to provide a degree of correlation, and determining the absence of a remote signal by detecting the degree of correlation of the echo estimate signal with the echo-canceled signal.
Claim 3
Dependent Claim
23 words
A method of claim 1 wherein the echo estimate signal further comprises a near-end echo estimate signal and a far-end echo estimate signal.
Claim 4
Dependent Claim
66 words
Apparatus comprising means for receiving a signal, means for subtracting an echo estimate signal from the received signal to provide an echo-canceled signal, means for correlating the echo estimate signal with the echo-canceled signal to provide a signal representative of the degree of correlation, and means for receiving the signal representative of the degree of correlation to determine the presence or absence of a remote signal.
Claim 5
Dependent Claim
66 words
Apparatus comprising means for receiving a signal, means for subtracting an echo estimate signal from the received signal to provide an echo-canceled signal, means for correlating the echo estimate signal with the echo-canceled signal to provide a signal representative of the degree of correlation, and means for receiving the signal representative of the degree of correlation to determine the presence or absence of a remote signal.
Claim 6
Dependent Claim
23 words
The apparatus of claim 3 wherein the echo estimate signal further comprises a near-end echo estimate signal and a far-end echo estimate signal
Claim 7
Dependent Claim
88 words
Modem apparatus comprising means for transmitting a first signal, means for receiving a second signal, echo canceler means to provide an echo estimate signal representative of the first signal, means for combining the echo estimate signal and the second signal to provide an echo-canceled signal, means for correlating the echo estimate signal with the echo-canceled signal to provide a signal representative of the degree of correlation, and means for receiving the signal representative of the degree of correlation to determine the presence or absence of a remote signal.
Claim 8
Dependent Claim
88 words
Modem apparatus comprising means for transmitting a first signal, means for receiving a second signal, echo canceler means to provide an echo estimate signal representative of the first signal, means for combining the echo estimate signal and the second signal to provide an echo-canceled signal, means for correlating the echo estimate signal with the echo-canceled signal to provide a signal representative of the degree of correlation, and means for receiving the signal representative of the degree of correlation to determine the presence or absence of a remote signal.
References Cited (Backward Citations)
US4707824A
Cited
US4769808A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-04-26 | 1996-10-26 | 1997-04-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-04-26 | 2000-10-26 | 2001-04-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-04-26 | 2004-10-26 | 2005-04-27 | $7700.00 | Window Closed / Lapsed |