Patent US3967102A successfully refreshed from Google Patents.
US3967102A
Expired / Lapsed
US
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Self-adjusting digital notch filter
Assignee: United States Department of the Air Force
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Filing: 1975-03-25
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Granted: 1976-06-29
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Expires: 1995-03-25
Abstract
Abstract Digital filter auto-adjustment to variations in input signals is achieved by normalizing the output of the second of two substantially identical series-connected digital filter stages and subtracting the normalized output of the second filter stage from its input to provide a measure of filter signal residue power. Deviations of the signal residue power from the preset limits of a signal residue power standard are detected and signals responsive thereto are used to appropriately adjust variable bandwidth constants in both filter stages.
Inventors
- 👤 Rainer F. McCown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:31
CPC Classifications
H; H03; H03H; H03H21/00; H03H21/0012; H03H21/002; H03H21/0021
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
104 words
The method of filtering a signal comprising the steps of filtering said signal with a first digital filter having given bandwidth characteristics, filtering the output of said first digital filter with a second digital filter having substantially the same bandwidth characteristics as said first digital filter, normalizing the output of said second digital filter, subtracting the normalized output of said second digital filter from its input to obtain the filter signal residue power, and varying the bandwidth control constants of said first and second digital filters in response to deviations between said signal residue power and limits defined by a signal residue power standard.
Claim 2
Independent Claim
104 words
The method of filtering a signal comprising the steps of filtering said signal with a first digital filter having given bandwidth characteristics, filtering the output of said first digital filter with a second digital filter having substantially the same bandwidth characteristics as said first digital filter, normalizing the output of said second digital filter, subtracting the normalized output of said second digital filter from its input to obtain the filter signal residue power, and varying the bandwidth control constants of said first and second digital filters in response to deviations between said signal residue power and limits defined by a signal residue power standard.
Claim 3
Dependent Claim
136 words
A self-adjusting digital notch filter comprising a first digital filter stage having variable notch constants, a second digital filter stage having variable notch constants, the output of said first filter stage being connected to the input of said second filter stage, means for normalizing the output of said second filter stage, differencing means for subtracting the normalized output of said second filter stage from its input to provide a measure of the filter signal residue power, a signal residue power standard having selected signal residue power limits, comparator means adapted to measure deviations between the output of said differencing means and the limits of said signal residue power standard, and a notch constant generator adapted to control the values of first and second filter stage notch constants in response to the output of said comparator means.
Claim 4
Dependent Claim
136 words
A self-adjusting digital notch filter comprising a first digital filter stage having variable notch constants, a second digital filter stage having variable notch constants, the output of said first filter stage being connected to the input of said second filter stage, means for normalizing the output of said second filter stage, differencing means for subtracting the normalized output of said second filter stage from its input to provide a measure of the filter signal residue power, a signal residue power standard having selected signal residue power limits, comparator means adapted to measure deviations between the output of said differencing means and the limits of said signal residue power standard, and a notch constant generator adapted to control the values of first and second filter stage notch constants in response to the output of said comparator means.
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) | 1979-06-29 | 1979-12-29 | 1980-06-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-29 | 1983-12-29 | 1984-06-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-29 | 1987-12-29 | 1988-06-29 | $7700.00 | Window Closed / Lapsed |