US4021623A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic H-register clear for prevention of erroneous convolution in digital adaptive echo canceller
Assignee: Comsat Corp
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Filing: 1975-10-23
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Granted: 1977-05-03
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Expires: 1995-10-23
Abstract
Abstract An automatic H-register clear system for the prevention of erroneous convolution in adaptive digital echo cancellers is disclosed. Incoming signals from the H-register are accumulated and compared to a predetermined threshold value and when the value is exceeded, the H-register is cleared with the occurrence of the internal housekeeping cycle of the echo canceller. The clearing of the H-register allows a new impulse response model to be generated from new sampled data. In one embodiment using analog implementation, the accumulation takes place using a sequence of signal processing of digital-to-analog conversion, full wave rectification followed by integration of the signal. In another preferred embodiment using a counter detection system, each word is compared to a threshold and if this value is exceeded, a counter is indexed. If the value of the count in the counter exceeds a predetermined number during the sampling interval, the H-register is cleared. In this latter embodiment, either analog or digital implementation can be used.
Inventors
- 👤 Henri G. Suyderhoud
- 👤 Michael Onufry, Jr.
- 👤 Eric R. Kauffman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:58
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/20; H04B3/23
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
84 words
A circuit for generating an automatic H-register clear signal for adaptive echo cancellers comprising: an accumulator receiving data from the H-register and determining the magnitude of words in the H-register; comparator means receiving the output of said accumulator and determining whether said output exceeds a fixed, predetermined value; and means synchronized with the housekeeping cycles of said echo canceller to transmit a clearing signal to said H-register with the occurrence of the internal housekeeping cycle of said canceller when said predetermined value is exceeded.
Claim 2
Dependent Claim
84 words
A circuit for generating an automatic H-register clear signal for adaptive echo cancellers comprising: an accumulator receiving data from the H-register and determining the magnitude of words in the H-register; comparator means receiving the output of said accumulator and determining whether said output exceeds a fixed, predetermined value; and means synchronized with the housekeeping cycles of said echo canceller to transmit a clearing signal to said H-register with the occurrence of the internal housekeeping cycle of said canceller when said predetermined value is exceeded.
Claim 3
Dependent Claim
45 words
The apparatus of claim 1 wherein said accumulator includes an adder and a storage means, said adder adding the accumulated sum stored in the said storage means with the incremental word input from the H-register to determine the total number of words in the H-register.
Claim 4
Dependent Claim
30 words
The apparatus of claim 2 wherein said comparator means comprises a comparator having a first input of the output of said accumulator and second input of a fixed reference signal.
Claim 5
Dependent Claim
29 words
The apparatus of claim 2 wherein said comparator comprises a flip-flop set with the accumulation of a value exceeding an initial bias value tending to keep the flip-flop closed.
Claim 6
Dependent Claim
41 words
The apparatus of claim 1, wherein said accumulator comprises a digital-to-analog converter for converting the digital H-words into analog form, a full wave rectifier coupled to the digital-to-analog converter and an integrator coupled to the output of said full wave rectifier.
Claim 7
Independent Claim
107 words
A method of generating an automatic H-register clear signal for an adaptive echo canceller comprising the steps of: comparing each word in the H-register to a predetermined threshold value; generating an output signal each time said threshold is exceeded, said output signal stepping a counter by one unit; comparing the number stored in the counter, which is indicative of the number of words exceeding the threshold, with a predetermined maximum number of words, said predetermined maximum number being based on a determination derived from echo canceller impulse response patterns; and generating an output signal to clear the H-register when the predetermined maximum number of words is exceeded.
Claim 8
Independent Claim
107 words
A method of generating an automatic H-register clear signal for an adaptive echo canceller comprising the steps of: comparing each word in the H-register to a predetermined threshold value; generating an output signal each time said threshold is exceeded, said output signal stepping a counter by one unit; comparing the number stored in the counter, which is indicative of the number of words exceeding the threshold, with a predetermined maximum number of words, said predetermined maximum number being based on a determination derived from echo canceller impulse response patterns; and generating an output signal to clear the H-register when the predetermined maximum number of words is exceeded.
Claim 9
Dependent Claim
25 words
The method of claim 6 wherein said step of comparing each word in the H-register to a predetermined threshold is accomplished in an analog mode.
Claim 10
Dependent Claim
25 words
The method of claim 6 wherein said step of comparing each word in the H-register to a predetermined threshold is accomplished in a digital mode.
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) | 1980-05-02 | 1980-11-01 | 1981-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-02 | 1984-11-01 | 1985-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-02 | 1988-11-01 | 1989-05-03 | $7700.00 | Window Closed / Lapsed |