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Patent US5226016A successfully refreshed from Google Patents.
US5226016A
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Adaptively formed signal-free reference system
Assignee: United States Department of the Navy
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Filing: 1992-04-16
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Granted: 1993-07-06
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Expires: 2012-04-16
Abstract
Abstract A method and apparatus are provided to adaptively form an optimum signal-free reference used to cancel near-field noise in an adaptive plate-noise cancellation system. First, second and third pressure sensors are positioned to detect any near-field plate-radiated noise. The first sensor is positioned closest to the plate, the third sensor is positioned furthest from the plate, and the second sensor is positioned between the first and third sensors. An acoustic far-field projector generates a plurality of broadband signals from a plurality of incidence angles. Each broadband signal is projected at an amplitude indicative of a noise-off condition. Outputs from the first and third sensors are combined to form a dipole responsive to each broadband signal). A feedback system is operatively associated with the dipole and the second sensor. The feedback system includes an adaptive filter that converges to generate an optimum signal-free reference for each of the plurality of the broadband signals and stores filter coefficients indicative of the optimum signal-free reference for each of the broadband signals. Switching means are provided to selectively switch the adaptive filter out of the feedback system such that the stored filter coefficients may be used.
Inventors
- 👤 Russel A. Christman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 07:49
CPC Classifications
G; G10; G10K; G10K11/00; G10K11/16; G10K11/175; G10K11/178; G10K11/1787; G10K11/17879; G10K11/17881; G10K11/1785; G10K11/17853; G10K11/17854; G10K11/17857; G10K2210/00; G10K2210/10; G10K2210/127; G10K2210/30; G10K2210/301; G10K2210/3011; G10K2210/3023; G10K2210/321; G10K2210/3216; Y; Y10; Y10S; Y10S367/00; Y10S367/901
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
178 words
A method of adaptively forming an optimum signal-free reference used to cancel near-field noise in an adaptive platenoise cancellation system, comprising the steps of: aligning, in the near-field of any generated plate-noise, first, second and third pressure sensors in a straight line normal to a plate, wherein the first sensor is positioned closest to the plate, the third sensor is positioned furthest from the plate, and the second sensor is positioned between the first and third sensors; subjecting the three sensors to a broadband signal from an acoustic far-field projector, the broadband signal having an amplitude effective to provide a noise-off condition; combining outputs from the first and third sensors to form a dipole responsive to the broadband signal; weighting, at an adaptive filter, an output from the second sensor responsive to the broadband signal; generating an error signal as the difference between the output from the dipole and the weighted output from the second sensor; and applying the error signal to the adaptive filter, wherein convergence of the adaptive filter is indicative of an optimum signal-free reference.
Claim 2
Independent Claim
178 words
A method of adaptively forming an optimum signal-free reference used to cancel near-field noise in an adaptive platenoise cancellation system, comprising the steps of: aligning, in the near-field of any generated plate-noise, first, second and third pressure sensors in a straight line normal to a plate, wherein the first sensor is positioned closest to the plate, the third sensor is positioned furthest from the plate, and the second sensor is positioned between the first and third sensors; subjecting the three sensors to a broadband signal from an acoustic far-field projector, the broadband signal having an amplitude effective to provide a noise-off condition; combining outputs from the first and third sensors to form a dipole responsive to the broadband signal; weighting, at an adaptive filter, an output from the second sensor responsive to the broadband signal; generating an error signal as the difference between the output from the dipole and the weighted output from the second sensor; and applying the error signal to the adaptive filter, wherein convergence of the adaptive filter is indicative of an optimum signal-free reference.
Claim 3
Dependent Claim
23 words
A method according to claim 1 further comprising the step of storing coefficients of the adaptive filter indicative of the optimum signal-free reference.
Claim 4
Dependent Claim
23 words
A method according to claim 1 wherein the broadband signal is successively propagated towards the three sensors from a plurality of incidence angles.
Claim 5
Dependent Claim
188 words
In an adaptive plate-noise cancellation system having first, second and third hydrophone pressure sensors aligned in a straight line normal to a plate, the first sensor being positioned closest to the plate, the third sensor being positioned furthest from the plate, and the second sensor being positioned between the first and third sensors, wherein all three sensors lie in the near-field of any generated plate- noise, a method of adaptively forming an optimum signal-free reference used to cancel near-field noise in the cancellation system comprising the steps of: successively subjecting the three sensors to a plurality of broadband signals projected from a plurality of incidence angles, each broadband signal having an amplitude indicative of a noise-off condition; combining outputs from the first and third sensors to form a dipole responsive to each of the broadband signals; providing, in operative association with the dipole and the second sensor, a feedback system having an adaptive filter that converges to generate an optimum signal-free reference for each of the broadband signals; and storing, for each of the broadband signals, filter coefficients of the adaptive filter indicative of the optimum signal-free reference.
Claim 6
Dependent Claim
188 words
In an adaptive plate-noise cancellation system having first, second and third hydrophone pressure sensors aligned in a straight line normal to a plate, the first sensor being positioned closest to the plate, the third sensor being positioned furthest from the plate, and the second sensor being positioned between the first and third sensors, wherein all three sensors lie in the near-field of any generated plate- noise, a method of adaptively forming an optimum signal-free reference used to cancel near-field noise in the cancellation system comprising the steps of: successively subjecting the three sensors to a plurality of broadband signals projected from a plurality of incidence angles, each broadband signal having an amplitude indicative of a noise-off condition; combining outputs from the first and third sensors to form a dipole responsive to each of the broadband signals; providing, in operative association with the dipole and the second sensor, a feedback system having an adaptive filter that converges to generate an optimum signal-free reference for each of the broadband signals; and storing, for each of the broadband signals, filter coefficients of the adaptive filter indicative of the optimum signal-free reference.
Claim 7
Independent Claim
195 words
An apparatus for adaptively forming an optimum signal-free reference used to cancel near-field noise in an adaptive platenoise cancellation system comprising: first, second and third pressure sensors aligned in a straight line normal to a plate and in the near-field of any generated plate-noise, wherein the first sensor is positioned closest to the plate, the third sensor is positioned furthest from the plate, and the second sensor is positioned between the first and third sensors; an acoustic far-field projector for generating a plurality of broadband signals projected from a plurality of incidence angles, each broadband signal being successively projected at an amplitude indicative of a noise-off condition; means for combining outputs from the first and third sensors to form a dipole responsive to each broadband signal; a feedback system, operationally associated with dipole and the second sensor, having an adaptive filter that converges to generate an optimum signal-free reference for each of the plurality of the broadband signals and stores filter coefficients indicative of the optimum signal-free reference for each of the broadband signals; and means for selectively switching said filter out of said feedback system, wherein said adaptive filter uses the stored filter coefficients.
Claim 8
Independent Claim
195 words
An apparatus for adaptively forming an optimum signal-free reference used to cancel near-field noise in an adaptive platenoise cancellation system comprising: first, second and third pressure sensors aligned in a straight line normal to a plate and in the near-field of any generated plate-noise, wherein the first sensor is positioned closest to the plate, the third sensor is positioned furthest from the plate, and the second sensor is positioned between the first and third sensors; an acoustic far-field projector for generating a plurality of broadband signals projected from a plurality of incidence angles, each broadband signal being successively projected at an amplitude indicative of a noise-off condition; means for combining outputs from the first and third sensors to form a dipole responsive to each broadband signal; a feedback system, operationally associated with dipole and the second sensor, having an adaptive filter that converges to generate an optimum signal-free reference for each of the plurality of the broadband signals and stores filter coefficients indicative of the optimum signal-free reference for each of the broadband signals; and means for selectively switching said filter out of said feedback system, wherein said adaptive filter uses the stored filter coefficients.
Claim 9
Dependent Claim
22 words
An apparatus as in claim 5 wherein the plate is a submarine hull and said first, second and third sensors are hydrophones.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-07-05 | 1997-01-04 | 1997-07-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-07-05 | 2001-01-04 | 2001-07-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-07-05 | 2005-01-04 | 2005-07-06 | $7700.00 | Window Closed / Lapsed |