US5097221A
Expired / Lapsed
US
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Adaptive filter technique for suppression of wideband or offset narrowband radio frequency interference
Assignee: United States Department of the Navy
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Filing: 1990-12-21
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Granted: 1992-03-17
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Expires: 2010-12-21
Abstract
Abstract The adaptive filter for frequency modulation of the present invention utilizes an audio tone multiplexed into the baseband modulation spectrum as a pilot tone to control and determine the amount of adaptation of the effective and variable bandwidth of the filter for optimum selectivity and rejection of wideband interference or narrowband offset interference. The multiplexed tone is detected and the filter is adjusted according to the signal-to-noise ratio of the detected tone. A continuous and adaptive decrease or increase in bandwidth is produced to accommodate the actual signal bandwidth to achieve rejection of interference with minimum distortion. Additionally, the filter compensates for transmitter drift of center frequency. This filter may be used at radio or intermediate frequencies.
Inventors
- 👤 Jeffry J. Miller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:35
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/06; H04B1/10; H04B1/1027; H03; H03D; H03D3/00; H03D3/001; H03D3/002; H04B2001/1054; H04B2001/1072
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
94 words
A method for adaptably filtering an input signal having a baseband modulation process, comprising the steps of: (a) providing a test signal within said baseband modulation spectrum of said input signal; (b) filtering said input signal by means of a first filter having a first filter pole to provide a first filtered signal; (c) first detecting said test signal within said first filtered signal and determining a signal-to-noise ratio in response to detecting said test signal; and (d) adjusting said first filter pole in accordance with said signal-to-noise ratio of said detected test signal.
Claim 2
Independent Claim
94 words
A method for adaptably filtering an input signal having a baseband modulation process, comprising the steps of: (a) providing a test signal within said baseband modulation spectrum of said input signal; (b) filtering said input signal by means of a first filter having a first filter pole to provide a first filtered signal; (c) first detecting said test signal within said first filtered signal and determining a signal-to-noise ratio in response to detecting said test signal; and (d) adjusting said first filter pole in accordance with said signal-to-noise ratio of said detected test signal.
Claim 3
Dependent Claim
46 words
The method for adaptively filtering an input signal of claim 1, wherein step (d) comprises the steps of: (e) providing a filter pole adjust signal in accordance with said signal-to-noise ratio; and (f) adjusting said first filter pole in accordance with said filter pole adjust signal.
Claim 4
Dependent Claim
31 words
The method for adaptively filtering an input signal claim 1, wherein step (c) is preceded by the further step of demodulating said first filtered signal to provide a first demodulated signal.
Claim 5
Dependent Claim
23 words
The method for filtering an input signal of claim 3, wherein step (c) comprises detecting said test signal within said first demodulated signal.
Claim 6
Dependent Claim
75 words
The method for filtering an input signal of claim 1, comprising the further steps of: (g) filtering said first filtered signal by means of a second filter having a second filter pole to provide a second filtered signal; (h) detecting said test signal within said second filtered signal and providing a first detection signal in response to detecting said test signal; and, (i) adjusting said second filter pole in accordance with the second detection signal.
Claim 7
Dependent Claim
38 words
The method for adaptively filtering an input signal of claim 1, comprising the further step of detecting a voltage level within said first filtered signal and providing a voltage level detection signal in accordance with said voltage level.
Claim 8
Dependent Claim
28 words
The method for adaptively filtering an input signal of claim 7, comprising the further step of adjusting said first pole in accordance with said voltage level detection signal.
Claim 9
Dependent Claim
27 words
The method for adaptively filtering an input signal of claim 1, comprising the further step of integrating said signal-to-noise ratio to provide an integrated first detection signal.
Claim 10
Dependent Claim
29 words
The method for adaptively filtering an input signal of claim 8, comprising the further step of adjusting said first filter pole in accordance with said integrated first detection signal.
Claim 11
Dependent Claim
95 words
An adaptive filter for adaptively filtering an input signal having a baseband modulation spectrum, comprising: means for providing a test signal within said baseband modulation spectrum of said input signal; first filter means for filtering said signal, said first filter means having a first filter pole to provide a first filtered signal; first detecting means for detecting said test signal within said first filtered signal and determining a signal-to-noise ratio in response to detecting said test signal; and, means for adjusting said first filter pole in accordance with the signal-to-noise ratio of said detected test.
Claim 12
Dependent Claim
95 words
An adaptive filter for adaptively filtering an input signal having a baseband modulation spectrum, comprising: means for providing a test signal within said baseband modulation spectrum of said input signal; first filter means for filtering said signal, said first filter means having a first filter pole to provide a first filtered signal; first detecting means for detecting said test signal within said first filtered signal and determining a signal-to-noise ratio in response to detecting said test signal; and, means for adjusting said first filter pole in accordance with the signal-to-noise ratio of said detected test.
Claim 13
Dependent Claim
47 words
The adaptive filter for adaptively filtering an input signal of claim 10, wherein said adjusting means comprises: means for providing a filter pole adjust signal in accordance with said signal-to-noise ratio; and means for adjusting said first filter pole in accordance with said filter pole adjust signal.
Claim 14
Dependent Claim
27 words
The adaptive filter for adaptively filtering an input signal claim 10, wherein further comprising means for demodulating said first filtered signal to provide a first demodulated signal.
Claim 15
Dependent Claim
25 words
The adaptive filter for adaptively filtering an input signal of claim 12, further comprising means for applying said demodulated signal to said first detecting means.
Claim 16
Dependent Claim
28 words
The adaptive filter for filtering an input signal of claim 12, wherein said first detecting means comprises means for detecting said test signal within said first demodulated signal.
Claim 17
Dependent Claim
69 words
The adaptive filter for filtering an input signal of claim 10, further comprising: second filtering means for filtering said first filtered signal, said second filtering means having a second filter pole to provide a second filtered signal; means for detecting said test signal within said second filtered signal and providing a second detection signal; and, means for adjusting said second filter pole in accordance with the second detection signal.
Claim 18
Dependent Claim
20 words
The adaptive filter for adaptively filtering an input signal of claim 10, wherein said test signal comprises an audio signal.
Claim 19
Dependent Claim
38 words
The adaptive filter for adaptively filtering an input signal of claim 10, further comprising means for detecting a voltage level within said second filtered signal and adjusting said first filter pole in accordance with said detected voltage level.
Claim 20
Dependent Claim
42 words
The adaptive filter for adaptively filtering an input signal of claim 10, further comprising means for integrating said second detection signal to provide an integrated second detection signal and adjusting said second filter pole in accordance with said integrated second detection signal.
Claim 21
Independent Claim
77 words
A method for adaptively filtering an input signal having a baseband modulation spectrum, comprising the steps of: (a) providing a test signal within said baseband modulation spectrum of said input signal; (b) filtering said input signal by means of a filter having a filter pole to provide a filtered signal; (c) demodulating said filtered signal to provide a demodulated signal; and, (d) detecting said test signal and providing a detection signal in response to said demodulated signal.
Claim 22
Independent Claim
77 words
A method for adaptively filtering an input signal having a baseband modulation spectrum, comprising the steps of: (a) providing a test signal within said baseband modulation spectrum of said input signal; (b) filtering said input signal by means of a filter having a filter pole to provide a filtered signal; (c) demodulating said filtered signal to provide a demodulated signal; and, (d) detecting said test signal and providing a detection signal in response to said demodulated signal.
Claim 23
Independent Claim
89 words
A method for adaptively filtering an input signal having a baseband modulation spectrum, comprising the steps of: (a) providing a voltage level signal within said baseband modulation spectrum of said input signal; (b) filtering said input signal by means of a first filter having a filter pole to provide a filtered signal; (c) detecting said voltage level signal within said filtered signal and providing a voltage level detection signal in accordance with said voltage level; and, (d) adjusting said filter pole in accordance with said voltage level detection signal.
Claim 24
Independent Claim
89 words
A method for adaptively filtering an input signal having a baseband modulation spectrum, comprising the steps of: (a) providing a voltage level signal within said baseband modulation spectrum of said input signal; (b) filtering said input signal by means of a first filter having a filter pole to provide a filtered signal; (c) detecting said voltage level signal within said filtered signal and providing a voltage level detection signal in accordance with said voltage level; and, (d) adjusting said filter pole in accordance with said voltage level detection signal.
Claim 25
Independent Claim
95 words
A method for adaptively filtering an input signal having a baseband modulation spectrum, comprising the steps of: (a) providing a test signal within said baseband modulation spectrum of said input signal; (b) filtering said input signal by means of a filter having a filter pole to provide a filtered signal; (c) detecting said test signal within said filtered signal and providing a detection signal in response to detecting said test signal; (d) integrating said detection signal to provide an integrated detection signal; and, (e) adjusting said filter pole in accordance with said integrated detection signal.
Claim 26
Independent Claim
95 words
A method for adaptively filtering an input signal having a baseband modulation spectrum, comprising the steps of: (a) providing a test signal within said baseband modulation spectrum of said input signal; (b) filtering said input signal by means of a filter having a filter pole to provide a filtered signal; (c) detecting said test signal within said filtered signal and providing a detection signal in response to detecting said test signal; (d) integrating said detection signal to provide an integrated detection signal; and, (e) adjusting said filter pole in accordance with said integrated detection signal.
References Cited (Backward Citations)
US4641181A
Cited
US4698598A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-03-17 | 1995-09-16 | 1996-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-17 | 1999-09-16 | 2000-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-17 | 2003-09-16 | 2004-03-17 | $7700.00 | Window Closed / Lapsed |