US3852708A
Expired / Lapsed
US
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Multiple element phased array with shaded sub-element groups
Assignee: Lockheed Martin Corp
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Filing: 1972-01-24
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Granted: 1974-12-03
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Expires: 1992-01-24
Abstract
Abstract An array of grouped transducer elements (i.e., groups of subelements with each group connected together in parallel to act as a single array element) is disclosed for use in a towed hydrophone array where the wavelength of unwanted noise signals has been discovered to be much shorter than the wavelength of signals for which a response is desired. In such a towed array, each group of sub-elements itself acts as an array with respect to the shorter wave length tow noise signals and improved performance of the overall (i.e., greater signal-to-noise ratio) oomposite array of elements is achieved by shading individual groups of sub-elements to minimize their responses to the unwanted noise signals. The exemplary embodiment is directed to a linear towed array of hydrophones intended for use in liquid mediums. When such an array is towed through the liquid medium, it has been discovered that so-called ''''tow noise'''' is generated and propagated mechanically along the physical structure of the array at a relatively low velocity whereas the acoustic waves travelling in the liquid medium (for which a response is actually desired) travel at a much higher velocity and therefore have a correspondingly greater wavelength. Thus, a single group of subelement hydrophones connected together may act as only a single element with respect to the longer wavelength acoustic waves of interest while at the same time the group will act as an array with respect to the tow noise propagating axially along the towed linear array. Accordingly, each group of transducers is shaded either by physical spacing and/or by proportioned hydrophone sensitivities etc., to result in minimizing the end-fire responses of the groups for the unwanted tow noise signal.
Inventors
- 👤 R Doolittle
- 👤 J Dorr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:36
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/38; G01V1/16; G01V1/20
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
101 words
A linear signal receiving array of grouped transducers comprising a plurality of substantially co-linear spaced-apart array elements adapted to respond to incident signals as a linear towed array in a liquid medium wherein each of said elements in the linear array itself comprises a group of substantially colinear individual transducers forming a second linear array within every element and wherein the second linear arrays within said elements are shaded to reduce their end-fire response characteristics with respect to locally generated tow noise propagating along and within the array at a velocity substantially less than the propagation velocity of said incident signals.
Claim 2
Dependent Claim
101 words
A linear signal receiving array of grouped transducers comprising a plurality of substantially co-linear spaced-apart array elements adapted to respond to incident signals as a linear towed array in a liquid medium wherein each of said elements in the linear array itself comprises a group of substantially colinear individual transducers forming a second linear array within every element and wherein the second linear arrays within said elements are shaded to reduce their end-fire response characteristics with respect to locally generated tow noise propagating along and within the array at a velocity substantially less than the propagation velocity of said incident signals.
Claim 3
Dependent Claim
44 words
An array as in claim 1, wherein said trasducers comprise hydrophones and the first-mentioned array is a linear array, adapted for towing in a liquid medium and wherein the second arrays are shaded to reduce response to noise signals caused by towing the array.
Claim 4
Dependent Claim
20 words
An array as in claim 1, wherein each shaded second array comprises a group of transducers with varying spacing therebetween.
Claim 5
Dependent Claim
20 words
An array as in claim 1, wherein each shaded second array comprises a group of transducers with varying effective sensitivites.
Claim 6
Dependent Claim
31 words
An array as in claim 1, wherein the second array of transducers comprising each element is shaded to minimize end-fire second array response to coherent noise signals propagating along the arrays.
Claim 7
Dependent Claim
107 words
A linear array of hydrophones adapted for towing in a liquid medium where coherent tow noise signals propagate along and within the array at a velocity substantially less than the propagation velocity of incident acoustic signals from the surrounding liquid medium, said array comprising: a linear array of hydrophone groups wherein each group of hydrophones is spaced with respect to other groups to function as one element of the linear array with respect to said higher velocity acoustic signals, and wherein each group of hydrophones itself comprises a linear array of individual hydrophones shaded to reduce the end-fire response of each group to said tow noise signals.
Claim 8
Dependent Claim
107 words
A linear array of hydrophones adapted for towing in a liquid medium where coherent tow noise signals propagate along and within the array at a velocity substantially less than the propagation velocity of incident acoustic signals from the surrounding liquid medium, said array comprising: a linear array of hydrophone groups wherein each group of hydrophones is spaced with respect to other groups to function as one element of the linear array with respect to said higher velocity acoustic signals, and wherein each group of hydrophones itself comprises a linear array of individual hydrophones shaded to reduce the end-fire response of each group to said tow noise signals.
Claim 9
Dependent Claim
24 words
A linear array as in claim 6, wherein each group of hydrophones is shaded due to a predetermined spacing of the individual hydrophones therein.
Claim 10
Dependent Claim
24 words
A linear array as in claim 6 wherein each group of hydrophones is shaded due to predetermined effective sensitivites of the individual hydrophones therein.
Claim 11
Dependent Claim
92 words
A group of transducers adapted for inclusion as one element of a first phased linear array of such elements, each group being of sufficiently small physical dimensions and spaced with respect to other groups to respond as a single element with respect to high velocity signals of interest and each group further comprising a second phase array of individual transducers therein which are shaded to reduce its end-fire response to unwanted noise signals propagating along and within said first array at a substantially lower velocity than said high velocity signals of interest.
Claim 12
Dependent Claim
92 words
A group of transducers adapted for inclusion as one element of a first phased linear array of such elements, each group being of sufficiently small physical dimensions and spaced with respect to other groups to respond as a single element with respect to high velocity signals of interest and each group further comprising a second phase array of individual transducers therein which are shaded to reduce its end-fire response to unwanted noise signals propagating along and within said first array at a substantially lower velocity than said high velocity signals of interest.
Claim 13
Dependent Claim
13 words
A group of transducers as in claim 9, wherein said transducers comprise hydrophones.
Claim 14
Dependent Claim
25 words
A group of transducers as in claim 9, wherein said second phased array is shaded due to a predetermined spacing of the individual transducers therein.
Claim 15
Dependent Claim
25 words
A group of transducers as in claim 9, wherein said second phase array is shaded due to predetermined effective sensitivities of the individual transducers therein.
Claim 16
Dependent Claim
127 words
A linear phased transducer array system for use in an environment where unwanted noise signals propagate along and within said array at a velocity substantially less than the propagation velocity of signals for which a response is desired, said system comprising: a first array of spaced apart elements for providing a plurality of phased output signals, and a phasing means connected to receive the plural phased output signals and combine them with predetermined phased relationships therebetween into a composite signal representing said signals for which a response is desired, each of said element means comprising a plurality of spaced apart individual transducers constituting a second linear array and wherein each said second arrays is shaded to reduce end-fire responses to the substantially lower velocity unwanted noise signals.
Claim 17
Dependent Claim
127 words
A linear phased transducer array system for use in an environment where unwanted noise signals propagate along and within said array at a velocity substantially less than the propagation velocity of signals for which a response is desired, said system comprising: a first array of spaced apart elements for providing a plurality of phased output signals, and a phasing means connected to receive the plural phased output signals and combine them with predetermined phased relationships therebetween into a composite signal representing said signals for which a response is desired, each of said element means comprising a plurality of spaced apart individual transducers constituting a second linear array and wherein each said second arrays is shaded to reduce end-fire responses to the substantially lower velocity unwanted noise signals.
Claim 18
Dependent Claim
21 words
A system as in claim 13 wherein the first array is a towed linear hydrophone array and said transducers comprise hydrophones.
Claim 19
Dependent Claim
22 words
A system as in claim 14 wherein each second array is shaded due to a predetermined spacing of the individual hydrophones therein.
Claim 20
Dependent Claim
22 words
A system as in claim 14 wherein each second array is shaded due to predetermined effective sensitivities of the individual hydrophones therein.
Claim 21
Independent Claim
160 words
A method of transducing desired acoustic signals with a linear array from a liquid medium and at the same time discriminating against substantially slower propagating noise signals within and along the array to thereby improve the signal-to-noise ratio, said method comprising the steps of: transducing acoustic signals to corresponding electrical signals at spaced apart intervals in said liquid medium, said spaced apart intervals defining a first linear array of spaced apart elements each of which elements itself comprises a spaced apart second linear array, shading the transducing intervals in each of said second arrays to discriminate against said substantially lower velocity noise signals, combining outputs from transducing intervals in each second array into a single element output signal, routing each element output signal to a central phasing means, and combining said element output signals with predetermined phase relationships therebetween within said phasing means to produce a composite output representing the desired higher velocity acoustic signals with an improved signal-to-noise ratio.
Claim 22
Independent Claim
160 words
A method of transducing desired acoustic signals with a linear array from a liquid medium and at the same time discriminating against substantially slower propagating noise signals within and along the array to thereby improve the signal-to-noise ratio, said method comprising the steps of: transducing acoustic signals to corresponding electrical signals at spaced apart intervals in said liquid medium, said spaced apart intervals defining a first linear array of spaced apart elements each of which elements itself comprises a spaced apart second linear array, shading the transducing intervals in each of said second arrays to discriminate against said substantially lower velocity noise signals, combining outputs from transducing intervals in each second array into a single element output signal, routing each element output signal to a central phasing means, and combining said element output signals with predetermined phase relationships therebetween within said phasing means to produce a composite output representing the desired higher velocity acoustic signals with an improved signal-to-noise ratio.
Claim 23
Dependent Claim
20 words
A method as in claim 17 wherein said shading step comprises variably spacing the transducing intervals in said second arrays.
Claim 24
Dependent Claim
27 words
A method as in claim 17 wherein said shading step comprises varying the effective sensitivities of hydrophone transducers situated at each transducing interval in said second arrays.
References Cited (Backward Citations)
US3364461A
Cited
US3441902A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-02 | 1978-06-03 | 1978-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-02 | 1982-06-03 | 1982-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-02 | 1986-06-03 | 1986-12-03 | $7700.00 | Window Closed / Lapsed |