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US3928840A
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Tracking system for underwater objects
Assignee: United States Department of the Navy
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Filing: 1974-04-19
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Granted: 1975-12-23
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Expires: 1994-04-19
Abstract
Abstract A system for tracking with high precision the movement of an underwater object having a sound detecting capability employs three bottom-moored acoustic signal sources which are generally disposed in a triangular pattern and continuously radiate acoustic signals which are clustered, for example, about 12 kc. The composite signal that is detected is processed so that each radiated signal is subsequently transformed into a pair of quadraturely phased signals which are proportional to the sine and cosine of the input phase angle. These signals are converted to digital form and, thereafter, supplied to a digital computer which determines the inverse tangent of the ratio of these pair of signals. The phase of each signal so determined may be utilized, for example, to ascertain the slant range changes of the object with respect to a three-dimensional coordinate system.
Inventors
- 👤 Robert C Spindel
- 👤 Robert P Porter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 17:53
CPC Classifications
G; G01; G01S; G01S5/00; G01S5/18; G01S5/30; G01S11/00; G01S11/14; G01S5/26
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
174 words
In a system for tracking the movement of an underwater object, the combination of first, second and third sound sources moored to the bottom of the ocean in a generally triangular pattern, said first, second and third sound sources continuously radiating acoustic signals of frequencies f1, f2 and f3, respectively, means for detecting the composite signal arriving at said object; means for processing said composite signal so as to produce first, second and third pairs of quadraturely phased signals which are proportional to the sine and cosine of the input phase angles of said signals f1, f2 And f3; means for converting said pairs of signals to digital signals at a pre-selected data rate; and computer means for processing said digital signals so as to determine the inverse tangent of the input phase angles and therefrom the instantaneous phases of signals f1, f2 and f3 at said object, said phases corresponding to changes in the slant range from said object to said sound sources as determined by the wavelengths of f1, f2 and f3.
Claim 2
Dependent Claim
174 words
In a system for tracking the movement of an underwater object, the combination of first, second and third sound sources moored to the bottom of the ocean in a generally triangular pattern, said first, second and third sound sources continuously radiating acoustic signals of frequencies f1, f2 and f3, respectively, means for detecting the composite signal arriving at said object; means for processing said composite signal so as to produce first, second and third pairs of quadraturely phased signals which are proportional to the sine and cosine of the input phase angles of said signals f1, f2 And f3; means for converting said pairs of signals to digital signals at a pre-selected data rate; and computer means for processing said digital signals so as to determine the inverse tangent of the input phase angles and therefrom the instantaneous phases of signals f1, f2 and f3 at said object, said phases corresponding to changes in the slant range from said object to said sound sources as determined by the wavelengths of f1, f2 and f3.
Claim 3
Dependent Claim
31 words
In an arrangement as defined in claim 1 wherein the differences between f1 and f2 and f2 and f3 are equal and correspond to an integral multiple of a particular audio-frequency.
Claim 4
Dependent Claim
52 words
In an arrangement as defined in claim 1 wherein means for processing said composite signal includes means for heterodyning said composite signal in a mixer with a local oscillator whose frequency is spaced from f2 by an amount such that the intermediate frequency signals resulting therefrom are in a low audio-frequency range.
Claim 5
Dependent Claim
116 words
In an arrangement as defined in claim 1 wherein said means for processing said composite signal so as to produce said first, second and third pairs of quadraturely phased signals further includes means for heterodyning said composite signal with a locally generated signal so as to produce intermediate frequency signals; first, second and third phase detectors, each of said phase detectors being tuned to a different one of the three intermediate frequency signals produced by said heterodyning action; and means for feeding said intermediate frequency signals to the inputs of said first, second and third phase detectors whereby said first, second and third pairs of quadraturely phased signals are produced in the different output circuits thereof.
Claim 6
Dependent Claim
195 words
In a system for tracking an object that is moving within the ocean, the combination of first, second and third acoustic sources moored to the bottom of the ocean in a generally triangular geometry, said first, second and third acoustic sources continuously radiating acoustic signals of frequencies f1, f2 and f3, respectively, which are within the audio portion of the spectrum; means for detecting the composite signal arriving at said object; means for processing said composite signal so as to produce first, second and third pairs of quadraturely phased signals which are proportional to the sine and cosine of the input phase angles of said signals f1, f2 and f3 at said object; means for transforming said pairs of signals into corresponding digital signals at a pre-selected data rate; and computer means for processing said digital signals so as to determine the sign associated with the ratio of each pair of signals, and for counting the number of changes of signs that occur during a given time interval, each change in sign corresponding to a change in the slant distance to said sources equal to one-fourth wavelength of the corresponding signals f1, f2 and f3.
Claim 7
Dependent Claim
195 words
In a system for tracking an object that is moving within the ocean, the combination of first, second and third acoustic sources moored to the bottom of the ocean in a generally triangular geometry, said first, second and third acoustic sources continuously radiating acoustic signals of frequencies f1, f2 and f3, respectively, which are within the audio portion of the spectrum; means for detecting the composite signal arriving at said object; means for processing said composite signal so as to produce first, second and third pairs of quadraturely phased signals which are proportional to the sine and cosine of the input phase angles of said signals f1, f2 and f3 at said object; means for transforming said pairs of signals into corresponding digital signals at a pre-selected data rate; and computer means for processing said digital signals so as to determine the sign associated with the ratio of each pair of signals, and for counting the number of changes of signs that occur during a given time interval, each change in sign corresponding to a change in the slant distance to said sources equal to one-fourth wavelength of the corresponding signals f1, f2 and f3.
Claim 8
Dependent Claim
22 words
In an arrangement as defined in claim 5 wherein the frequency differences between f1 and f2 and f2 and f3 are equal.
Claim 9
Dependent Claim
41 words
In an arrangement as defined in claim 5 wherein said means for processing said composite signal includes means for heterodyning said composite signals with an audio-frequency so as to produce intermediate frequency signals in a low part of the audio-frequency range.
Claim 10
Dependent Claim
122 words
In an arrangement as defined in claim 7 wherein said means for processing said composite signal further includes a low pass filter adapted to pass frequencies up to and including that of the highest intermediate frequency signal produced by said heterodyning action; means for feeding said intermediate frequency signals to the input of said low pass filter; first, second and third phase detectors, each of Said phase detectors being tuned to a different one of the three intermediate frequency signals resulting from said heterodyning action; and means for feeding the output of said low pass filter to the inputs of said phase detectors whereby said first, second and third pairs of quadraturely phased signals are produced in the different output circuits thereof.
References Cited (Backward Citations)
US3421138A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |