Patent US3647992A successfully refreshed from Google Patents.
US3647992A
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Adaptive echo canceller for nonlinear systems
Assignee: AT&T Inc
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Filing: 1970-03-05
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Granted: 1972-03-07
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Expires: 1990-03-05
Abstract
Abstract Operation of a closed-loop echo cancellation system for use in a two-way communication circuit is improved by employing a multidimensional network capable of approximating a large class of nonlinear transfer functions, and a control circuit arrangement for automatically adjusting parameters of the network. Signals incoming to a four-wire to two-wire junction are supplied to the network which, supplied with an error signal derived from signals in the outgoing path, develops a replica of an undesired echo. The replica signal is subtracted from outgoing signals and the differential is used for the derivation of a new error signal.
Inventors
- 👤 Edmond Joseph Thomas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:21
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/20; H04B3/23
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
86 words
An echo canceller which comprises: adjustable signal-processing means connected to receive signals from the first of two one-way transmission paths of a communication system, said processing means including a generalized network for producing a plurality of combinations of selected transformations of signals received from said first one-way path, means connected in the second of said two one-way paths for differentially combining signals in said second path with signals supplied from said processing means, and means responsive to said differentially combined signals for adjusting said processing means.
Claim 2
Dependent Claim
86 words
An echo canceller which comprises: adjustable signal-processing means connected to receive signals from the first of two one-way transmission paths of a communication system, said processing means including a generalized network for producing a plurality of combinations of selected transformations of signals received from said first one-way path, means connected in the second of said two one-way paths for differentially combining signals in said second path with signals supplied from said processing means, and means responsive to said differentially combined signals for adjusting said processing means.
Claim 3
Dependent Claim
75 words
An echo canceller as defined in claim 1, wherein, said generalized network comprises a delay line system tapped for providing signals at Nyquist intervals, a plurality of interconnected multiplier networks selectively supplied with said Nyquist interval signals for developing products thereof in defined combinations, means for selectively weighting said product signals in accordance with the magnitude of signals from the second of said one-way paths, and means for adding all of said weighted signals together.
Claim 4
Dependent Claim
98 words
An echo canceller insensitive to transmission path nonlinearities which comprises: adjustable signal processing means connected to receive signals from the first of two one-way transmission paths of a communication system, said processing means including a multidimensional system of orthonormal filters for producing a plurality of transformations of signals received from said first one-way path, and means for selectively summing all of said transformation; means connected in the second of said two one-way paths for combining signals in said second path with said summation of transformation signals; and means responsive to said combined signals for adjusting said processing means.
Claim 5
Dependent Claim
98 words
An echo canceller insensitive to transmission path nonlinearities which comprises: adjustable signal processing means connected to receive signals from the first of two one-way transmission paths of a communication system, said processing means including a multidimensional system of orthonormal filters for producing a plurality of transformations of signals received from said first one-way path, and means for selectively summing all of said transformation; means connected in the second of said two one-way paths for combining signals in said second path with said summation of transformation signals; and means responsive to said combined signals for adjusting said processing means.
Claim 6
Dependent Claim
99 words
An echo canceller as defined in claim 3, wherein, said system for producing a plurality of signal transformations comprises, a plurality of generalized filter networks, each adapted to develop selectively altered versions of signals supplied from said first one-way path, an arrangement of multiplier means associated with each of said networks for developing products of said altered versions of signals taken n at a time where values of n from 1 to N are assigned respectively to each of said arrangements, and means for adjusting each of said product signals in accordance with a function of said combined signal.
Claim 7
Dependent Claim
91 words
An echo canceller as defined in claim 3, wherein, said system for producing a plurality of signal transformations comprises, a generalized filter network adapted to develop selectively altered versions of signals supplied from said first one-way path, a plurality of arrangements of multipliers for developing products of said altered versions of signals taken n at a time where values of n from 1 to N are assigned respectively to each of said arrangements, and means for adjusting each of said product signals in accordance with a function of said combined signal.
Claim 8
Dependent Claim
27 words
An echo canceller as defined in claim 4, wherein, each of said plurality of generalized filter networks includes a transversal filter for producing signals at Nyquist intervals.
Claim 9
Dependent Claim
25 words
An echo canceller a defined in claim 4, wherein, each of said plurality of generalized filter networks includes a cascaded chain of individual Laguerre networks.
Claim 10
Dependent Claim
117 words
In a closed loop, adaptive echo cancellation system for use in a two-way communications signal circuit, the combination which comprises: a processing network supplied with signals incoming to a four-wire to two-wire junction for developing a plurality of selectively altered signals, means for combining said altered signals to produce a plurality of combinations of all of said altered signals taken n at a time, where n is selected to range from n 1 to n N, means for selectively mixing each of said combined signals with a signal proportional to the amplitude of signals outgoing from said junction, and means for selectively combining said mixed signals to produce a signal approximation to leakage signals traversing said junction.
Claim 11
Dependent Claim
117 words
In a closed loop, adaptive echo cancellation system for use in a two-way communications signal circuit, the combination which comprises: a processing network supplied with signals incoming to a four-wire to two-wire junction for developing a plurality of selectively altered signals, means for combining said altered signals to produce a plurality of combinations of all of said altered signals taken n at a time, where n is selected to range from n 1 to n N, means for selectively mixing each of said combined signals with a signal proportional to the amplitude of signals outgoing from said junction, and means for selectively combining said mixed signals to produce a signal approximation to leakage signals traversing said junction.
Claim 12
Dependent Claim
32 words
The combination for use in an echo cancellation system, as defined in claim 8, wherein, said processing network develops selectively altered signals at Nyquist intervals of said signals incoming to said junction.
Claim 13
Dependent Claim
25 words
The combination for use in an echo cancellation system, as defined in claim 8, wherein, said processing network includes an arrangement of multidimensional orthonormal filters.
Claim 14
Independent Claim
81 words
A system for cancelling echoes arising in nonlinear circuits, which comprises; a network, supplied with signals from the first of two one-way transmission paths interconnecting said circuits, for producing a plurality of selectively adjusted product signals therefrom, means for selectively combining said adjusted product signals, means connected in the second of said two one-way paths for differentially combining signals in said second path with said combined product signals, and means responsive to said differentially combined signals for adjusting said product network.
Claim 15
Independent Claim
81 words
A system for cancelling echoes arising in nonlinear circuits, which comprises; a network, supplied with signals from the first of two one-way transmission paths interconnecting said circuits, for producing a plurality of selectively adjusted product signals therefrom, means for selectively combining said adjusted product signals, means connected in the second of said two one-way paths for differentially combining signals in said second path with said combined product signals, and means responsive to said differentially combined signals for adjusting said product network.
Claim 16
Dependent Claim
116 words
Nonlinear synthesis apparatus which comprises, a network supplied with signals incoming to a nonlinear circuit for developing a plurality of selectively altered signals, means for combining said altered signals to produce a plurality of combinations of all of said altered signals taken n at a time, where n is selected to range from n 1 to n N, means for selectively mixing of each of said combined signals with a signal proportional to the amplitude of signals outgoing from said nonlinear circuit, means for selectively combining said mixed signals to produce a signal approximation to nonlinear signals traversing said circuit, and means for differentially combining said signal approximation and said signals outgoing from said nonlinear circuit.
Claim 17
Dependent Claim
116 words
Nonlinear synthesis apparatus which comprises, a network supplied with signals incoming to a nonlinear circuit for developing a plurality of selectively altered signals, means for combining said altered signals to produce a plurality of combinations of all of said altered signals taken n at a time, where n is selected to range from n 1 to n N, means for selectively mixing of each of said combined signals with a signal proportional to the amplitude of signals outgoing from said nonlinear circuit, means for selectively combining said mixed signals to produce a signal approximation to nonlinear signals traversing said circuit, and means for differentially combining said signal approximation and said signals outgoing from said nonlinear circuit.
References Cited (Backward Citations)
US3465106A
Cited
US3500000A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-03-07 | 1975-09-06 | 1976-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-07 | 1979-09-06 | 1980-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-07 | 1983-09-06 | 1984-03-07 | $7700.00 | Window Closed / Lapsed |