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US5091890A
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Method of extracting target range and Doppler information from a Doppler-spread signal
Assignee: United States Department of the Navy
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Filing: 1991-05-20
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Granted: 1992-02-25
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Expires: 2011-05-20
Abstract
Abstract A method of extracting target range and Doppler information from a Dopplepread signal is provided. An acoustic waveform is transmitted underwater and impinges upon a submerged Doppler-spread target. Doppler-spread sonar echoes resulting from the transmitted waveform are received and digitized. The received sonar echo is separated into its inphase and quadrature components thereby forming a complex vector function. A fourth-order cumulant spectrum is generated from the complex vector function based upon three time delays. In order to extract the range and Doppler information from the Doppler-spread signal, the first of the time delays is set equal to zero while the second and third time delays are set equal to one another.
Inventors
- 👤 Roger F. Dwyer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 14:17
CPC Classifications
G; G01; G01S; G01S15/00; G01S15/02; G01S15/50; G01S15/52; G01S7/00; G01S7/52; G01S7/539; Y; Y10; Y10S; Y10S367/00; Y10S367/904
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
105 words
A method of extracting target range and Doppler information from an active sonar echo created by the target, said method being unaffected by Doppler-spreading and comprising the steps of: transmitting a series of acoustic pulses into a medium; receiving sonar echoes from the target associated with said transmitted series of pulses; matching said transmitted series of pulses to said received sonar echoes to extract a transmitted frequency from said received sonar echoes to generate a complex vector function; and filtering said complex vector function to generate a fourth-order cumulant spectrum wherein said spectrum is indicative of the target range and Doppler information, independent of Doppler-spreading.
Claim 2
Independent Claim
105 words
A method of extracting target range and Doppler information from an active sonar echo created by the target, said method being unaffected by Doppler-spreading and comprising the steps of: transmitting a series of acoustic pulses into a medium; receiving sonar echoes from the target associated with said transmitted series of pulses; matching said transmitted series of pulses to said received sonar echoes to extract a transmitted frequency from said received sonar echoes to generate a complex vector function; and filtering said complex vector function to generate a fourth-order cumulant spectrum wherein said spectrum is indicative of the target range and Doppler information, independent of Doppler-spreading.
Claim 3
Dependent Claim
33 words
A method as in claim 1 wherein said fourth-order cumulant spectrum is a function of three time delays wherein a first time delay is zero and second and third time delays are equal.
Claim 4
Dependent Claim
11 words
A method as in claim 1 wherein the medium is water.
Claim 5
Dependent Claim
11 words
A method as in claim 1 wherein the target exhibits motion.
Claim 6
Dependent Claim
11 words
A method as in claim 1 wherein the target is stationary.
Claim 7
Independent Claim
126 words
A method of extracting underwater target range and Doppler information from an active sonar echo, comprising the steps of: receiving the sonar echo as a function of time; segmenting the received sonar echo into sonar echo segments indicative of a particular range; digitizing each sonar echo segment; separating each sonar echo segment into its inphase and quadrature components wherein said inphase and quadrature components comprise a complex vector function representative of the sonar echoes; generating a fourth-order cumulant from said complex vector function wherein said fourth-order cumulant is a function of three time delays, a first time delay of zero, and second and third time delays equal to one another; and performing the fast Fourier Transform on said fourth-order cumulant to obtain a fourth-order cumulant spectrum.
Claim 8
Independent Claim
126 words
A method of extracting underwater target range and Doppler information from an active sonar echo, comprising the steps of: receiving the sonar echo as a function of time; segmenting the received sonar echo into sonar echo segments indicative of a particular range; digitizing each sonar echo segment; separating each sonar echo segment into its inphase and quadrature components wherein said inphase and quadrature components comprise a complex vector function representative of the sonar echoes; generating a fourth-order cumulant from said complex vector function wherein said fourth-order cumulant is a function of three time delays, a first time delay of zero, and second and third time delays equal to one another; and performing the fast Fourier Transform on said fourth-order cumulant to obtain a fourth-order cumulant spectrum.
References Cited (Backward Citations)
US4980868A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1995-02-24 | 1995-08-26 | 1996-02-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-24 | 1999-08-26 | 2000-02-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-24 | 2003-08-26 | 2004-02-25 | $7700.00 | Window Closed / Lapsed |