US3780233A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Adpative echo cancellers with compandors
Assignee: Comsat Corp
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Filing: 1971-09-20
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Granted: 1973-12-18
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Expires: 1991-09-20
Abstract
Abstract An echo canceller with compandors results in improved echo return loss enhancement. The incoming signal is compressed prior to its application to a digital transversal filter. The filter produces an approximation of the integral of the syllabically compressed incoming signal times a replica of the impulse response of an echo return path including a compressor. The echo signal is also syllabically compressed and applied to an adaptive control loop wherein the approximation is subtracted from the echo and the replica of the impulse response is varied in accordance with the difference obtained.
Inventors
- 👤 S Campanella
- 👤 H Suyderhoud
- 👤 M Onufry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 05:19
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/20; H04B3/23
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
135 words
In an echo canceller of the type which includes, a transversal filter means for performing convolution of an input signal on a receive line and a replica of the impulse response of an echo path to generate an approximation of an echo signal for subtraction, in a subtraction means, from the real echo signal on the send line, and an adaptive control loop responsive to the residual echo resulting from said subtraction to update the replica of the impulse response stored in the transversal filter, the improvement comprising: a. means connected to the send line on the input side of said subtraction means for increasing the power of the echo signal, and b. means connected to said send line on the output side of said subtraction means for reducing the power of said residual echo.
Claim 2
Dependent Claim
135 words
In an echo canceller of the type which includes, a transversal filter means for performing convolution of an input signal on a receive line and a replica of the impulse response of an echo path to generate an approximation of an echo signal for subtraction, in a subtraction means, from the real echo signal on the send line, and an adaptive control loop responsive to the residual echo resulting from said subtraction to update the replica of the impulse response stored in the transversal filter, the improvement comprising: a. means connected to the send line on the input side of said subtraction means for increasing the power of the echo signal, and b. means connected to said send line on the output side of said subtraction means for reducing the power of said residual echo.
Claim 3
Dependent Claim
29 words
An echo canceller as claimed in claim 1 further comprising means connected between said receive line and said transversal filter for reducing the amplitude distribution of said input signal.
Claim 4
Dependent Claim
38 words
An echo canceller as claimed in claim 1 wherein said means for increasing the power is a syllabic compressor, and said means for decreasing the power is a syllabic expander having the reverse input/output characteristic of said compressor.
Claim 5
Dependent Claim
73 words
An echo canceller as claimed in claim 3 further comprising a second compressor connected in said receive line at a point prior to the application of signals on said receive line to said transversal filter, and a second expandor connected in said receive line at a point subsequent to the application of signals on said receive line to said transversal filter, said second syllabic compressor and second syllabic expander having reverse input/output characteristics.
Claim 6
Dependent Claim
62 words
An echo canceller as claimed in claim 3 further comprising, a power divider means connected to said receive line for providing two attenuated replicas of signals appearing on said receive line, and a second syllabic compressor connected to said power divider and said transversal filter for compressing the signal from said power divider and applying the compressed signal to said transversal filter.
References Cited (Backward Citations)
US2825764A
Cited
US3500000A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-17 | 1977-06-18 | 1977-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-17 | 1981-06-18 | 1981-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-17 | 1985-06-18 | 1985-12-18 | $7700.00 | Window Closed / Lapsed |