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US4635240A
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Sonar navigation system
Assignee: Northrop Grumman Corp
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Filing: 1985-03-26
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Granted: 1987-01-06
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Expires: 2005-03-26
Abstract
Abstract A forward look sonar system in which speed and direction of a sonar platform is obtained. Each acoustic transmission towards the target area over which the platform is traveling is comprised of a plurality of frequencies. A plurality of receiver beams is formed and each individual beam from one transmission is cross-correlated with its corresponding beam from a selected subsequent transmission to derive a delay value. The later received signal for each beam, for each frequency is divided into a plurality of small segments each of which is cross-correlated with a portion of the first return signal corresponding to the same frequency and beam. The cross-correlation functions for the plurality of frequencies for each particular segment are added together to obtain a more precise delay value. The correlation functions for each of the beams are added together and compared to derive a value for platform direction in the intercomparison period and the delay values are utilized to derive a velocity indication.
Inventors
- 👤 Kenneth P. Geohegan, Jr.
- 👤 Charles W. Allen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:07
CPC Classifications
G; G01; G01S; G01S15/00; G01S15/02; G01S15/50; G01S15/58; G01S15/60
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
183 words
A sonar navigation system comprising: (A) sonar means on a sonar platform operable to forwardly transmit a broadband acoustic signal toward the bed of a body of water over which the platform is traveling and to repeat the transmission of said signal in repetitive transmission cycles, during the course of said travel; (B) means on said platform for receiving acoustic returns resulting from said transmissions; (C) means forming a plurality of individual receiver beam signals in response to a single transmission and reception; (D) means for cross-correlating segments of each beam signal from one transmission with respective corresponding beam signals from another transmission to derive a delay indication for each said segment cross-correlation; (E) means responsive to said delay indications to derive a velocity value indicative of platform speed; (F) means responsive to said cross-correlation of all of said segments of all of said beams to derive a cross-correlation amplitude value for each said beam; (G) means responsive to all of said beam amplitude values to derive a value for platform angular deviation from its travel path, from one transmission to a next.
Claim 2
Dependent Claim
183 words
A sonar navigation system comprising: (A) sonar means on a sonar platform operable to forwardly transmit a broadband acoustic signal toward the bed of a body of water over which the platform is traveling and to repeat the transmission of said signal in repetitive transmission cycles, during the course of said travel; (B) means on said platform for receiving acoustic returns resulting from said transmissions; (C) means forming a plurality of individual receiver beam signals in response to a single transmission and reception; (D) means for cross-correlating segments of each beam signal from one transmission with respective corresponding beam signals from another transmission to derive a delay indication for each said segment cross-correlation; (E) means responsive to said delay indications to derive a velocity value indicative of platform speed; (F) means responsive to said cross-correlation of all of said segments of all of said beams to derive a cross-correlation amplitude value for each said beam; (G) means responsive to all of said beam amplitude values to derive a value for platform angular deviation from its travel path, from one transmission to a next.
Claim 3
Dependent Claim
19 words
Apparatus according to claim 1 wherein: (A) each of said transmitted acoustic signals includes a plurality of different frequencies.
Claim 4
Dependent Claim
24 words
Apparatus according to claim 2 wherein: (A) each of said transmitted acoustic signals is a relatively short pulse comprised of subpulses of different frequencies;
Claim 5
Dependent Claim
29 words
Apparatus according to claim 3 wherein: (A) each said segment of said beam signal is cross-correlated with only a portion of said corresponding beam signal from said another transmission.
Claim 6
Dependent Claim
36 words
Apparatus according to claim 4 which includes: (A) means for determining the approximate distance travelled by said sonar means between one transmission and the next; (B) means responsive to said approximate distance to determine said portions.
Claim 7
Dependent Claim
28 words
Apparatus according to claim 4 wherein: (A) each segment of said beam signal is cross-correlated with only a portion of a corresponding beam signal from a previous transmission.
Claim 8
Dependent Claim
19 words
Apparatus according to claim 3 wherein: (A) a beam signal is derived for each one of said different frequencies.
Claim 9
Dependent Claim
59 words
Apparatus according to claim 1 which includes: (A) means to obtain an indication of platform yaw; (B) means responsive to said yaw indication to insure that a beam signal corresponding to a beam B j from one transmission is cross-correlated with the beam signal corresponding to beam B j from said another transmission, when B j represents any beam.
Claim 10
Dependent Claim
14 words
Apparatus according to claim 1 wherein: (A) said platform is a towed underwater body.
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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) | 1990-01-05 | 1990-07-07 | 1991-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-05 | 1994-07-07 | 1995-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-05 | 1998-07-07 | 1999-01-06 | $7700.00 | Window Closed / Lapsed |