US4845746A
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Echo canceller with relative feedback control
Assignee: Charles Industries Ltd
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Filing: 1987-06-23
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Granted: 1989-07-04
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Expires: 2007-06-23
Abstract
Abstract A method for selecting feedback constants for two echo cancellers in an adaptive 2-wire to 2-wire repeater. The repeater is connected to two networks and when signals are received from both networks, the signal having the greater energy level is identified. A feedback constant of the echo canceller associated with the greater signal is set independent of the feedback constant of the other echo canceller. The feedback constant of the other echo canceller is set as a function of a ratio of the signal energy level of a lesser of to larger of the two signals received from the networks.
Inventors
- 👤 Chan E. Li
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:04
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/20; H04B3/23; H04B3/234; H04B3/237
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
146 words
A method for selecting feedback constants for at least first and second echo cancellers in a 2-wire to 2-wire repeater connected between first and second networks, said repeater processing a first signal received from the first network to produce a RCVb signal and processing a second signal received from the second network to produce a RCVa signal, comprising: comparing an energy level of said RCVa signal (energy (RVCa)) to an energy level of said RCVb signal (energy (RCVb)) and if said energy level of said RCVa signal is greater than or equal to the energy level of said RCVb signal, then; setting a feedback constant, Ka, of the first echo canceller to K1×(1/energy (RCVa)), where K1 is a first predetermined constant; and setting a feedback constant, Kb, of the second echo canceller to Kb =Ka ×K2 ×(energy (RCVb)/energy (RCVa)), where K2 is a second predetermined constant.
Claim 2
Independent Claim
146 words
A method for selecting feedback constants for at least first and second echo cancellers in a 2-wire to 2-wire repeater connected between first and second networks, said repeater processing a first signal received from the first network to produce a RCVb signal and processing a second signal received from the second network to produce a RCVa signal, comprising: comparing an energy level of said RCVa signal (energy (RVCa)) to an energy level of said RCVb signal (energy (RCVb)) and if said energy level of said RCVa signal is greater than or equal to the energy level of said RCVb signal, then; setting a feedback constant, Ka, of the first echo canceller to K1×(1/energy (RCVa)), where K1 is a first predetermined constant; and setting a feedback constant, Kb, of the second echo canceller to Kb =Ka ×K2 ×(energy (RCVb)/energy (RCVa)), where K2 is a second predetermined constant.
Claim 3
Dependent Claim
46 words
The method described in claim 1, wherein said method further comprises, if said feedback constant, Kb, is less than a third predetermined constant, K3, and if the feedback constant, Ka, is greater than zero, setting the feedback constant, Kb, equal to the third predetermined constant, K3.
Claim 4
Dependent Claim
61 words
The method described in claim 1, wherein if said energy level of said RCVa signal is less than said energy level of said RCVb signal, then said method further comprises; setting said feedback constant, Kb, of the second echo canceller to K1 ×(1/energy (RCVb)); and setting said feedback constant, Ka, of the first echo canceller to Kb ×K2 ×(energy (RCVa)/energy (RCVb)).
Claim 5
Dependent Claim
46 words
The method described in claim 3, wherein said method further comprises, if said feedback constant, Ka, is less than said third predetermined constant, K3, and if the feedback constant, Kb, is greater than zero, setting the feedback constant, Ka, equal to said third predetermined constant, K3.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-03 | 1993-01-02 | 1993-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-03 | 1997-01-02 | 1997-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-03 | 2001-01-02 | 2001-07-04 | $7700.00 | Window Closed / Lapsed |