Patent US3801937A successfully refreshed from Google Patents.
US3801937A
Expired / Lapsed
US
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Acoustic pulse compression weighting filter transducer
Assignee: Raytheon Co
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Filing: 1973-02-20
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Granted: 1974-04-02
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Expires: 1993-02-20
Abstract
Abstract In order to improve the resolution of radar systems, one present practice is to interpose a pulse expansion filter in the transmitting channel of the radar system in conjunction with a pulse compression filter in the receiving channel whereby a longer pulse is transmitted than is applied to the detection apparatus of the system. When such a ''''pulse compression'''' system is used without weighting, the filter time sidelobe responses limit the resolution of adjacent targets to 13 decibels difference in amplitude. In accordance with the present invention, a class of unapodized nondispersive acoustic surface wave transducers is realized having spectral response functions that provide spectral weighting for time sidelobe reduction in pulse compression filters to extend the resolving power of a pulse compression radar system to as much as 43 decibels.
Inventors
- 👤 T Bristol
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 04:26
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/30; H03H9/42; H03H9/44
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
255 words
A surface wave transducer adapted to provide weighting for a pulse compression filter of bandwidth, B, with a mean frequency, fo, said transducer having a frequency domain spectral response, H(f), which has a time domain impulse response, h(t), including a center impulse and first and second equal flanking impulses spaced 1/B therefrom and of an amplitude that is predetermined fraction less than one of the amplitude of said center impulse, said surface wave transducer comprising; a. means for providing a piezoelectric substrate; b. first and second spaced parallel electrical pads disposed coextensively on said substrate; c. means including (m+1) finger-shaped electrodes of a predetermined length spaced one-half wavelength, at said frequency, fo, along said substrate and connected to said first and second electrical pads for providing a central electroacoustic transducer having m sources where m is a positive integer no less than three; and d. means disposed on each side of said central electro-acoustic transducer each including no more than (n+1) finger-shaped electrodes of said predetermined length spaced one-half wavelength at said frequency, fo, along said substrate and connected to said first and second electrical pads for providing first and second flanking electro-acoustic transducers each having n sources where n is a positive integer no less than one, said first and second electro-acoustic transducers being spaced a predetermined distance from said central transducer equivalent to introducing a delay equal to 1/B between the respective centers thereof, n/m being substantially equal to said predetermined fraction and m and n both being odd or both being even.
Claim 2
Dependent Claim
255 words
A surface wave transducer adapted to provide weighting for a pulse compression filter of bandwidth, B, with a mean frequency, fo, said transducer having a frequency domain spectral response, H(f), which has a time domain impulse response, h(t), including a center impulse and first and second equal flanking impulses spaced 1/B therefrom and of an amplitude that is predetermined fraction less than one of the amplitude of said center impulse, said surface wave transducer comprising; a. means for providing a piezoelectric substrate; b. first and second spaced parallel electrical pads disposed coextensively on said substrate; c. means including (m+1) finger-shaped electrodes of a predetermined length spaced one-half wavelength, at said frequency, fo, along said substrate and connected to said first and second electrical pads for providing a central electroacoustic transducer having m sources where m is a positive integer no less than three; and d. means disposed on each side of said central electro-acoustic transducer each including no more than (n+1) finger-shaped electrodes of said predetermined length spaced one-half wavelength at said frequency, fo, along said substrate and connected to said first and second electrical pads for providing first and second flanking electro-acoustic transducers each having n sources where n is a positive integer no less than one, said first and second electro-acoustic transducers being spaced a predetermined distance from said central transducer equivalent to introducing a delay equal to 1/B between the respective centers thereof, n/m being substantially equal to said predetermined fraction and m and n both being odd or both being even.
Claim 3
Dependent Claim
27 words
The surface wave transducer adapted to provide weighting for a pulse compression filter as defined in claim 1 wherein the quantity fo/Bm is no less than one.
Claim 4
Dependent Claim
46 words
The surface wave transducer adapted to provide weighting for a pulse compression filter as defined in claim 1 wherein said first and second electrical pads additionally include pedestal-shaped electrical pads coextensive with the respective widths of said central and said first and second flanking electro-acoustic transducers.
Claim 5
Dependent Claim
230 words
A surface wave transducer adapted to provide cosine-on-a-pedestal weighting over a bandwidth B having a mean frequency, fo, where the peak of the cosine-on-a-pedestal function is normalized at 1 and the lowest points thereof and designated a whereby a is greater than zero and less than one, said surface wave transducer comprising: a. means for providing a piezoelectric substrate; b. first and second spaced parallel longitudinal electrical pads disposed coextensively on said substrate; c. means including (m+1) finger-shaped electrodes of a predetermined length spaced one-half wavelength, at said frequency, fo, along said substrate and connected to said first and second electrical pads for providing a central electro-acoustic transducer having m sources where m is a positive integer no less than three; and d. means disposed on opposite sides of said central electro-acoustic transducer each including no more than (n+1) finger-shaped electrodes of said predetermined length spaced one-half wavelength at said frequency, fo, along said substrate and connected to said first and second electrical pads for providing first and second electro-acoustic transducers each having n sources where n is a positive integer no less than one, said first and second electro-acoustic transducers being spaced a predetermined distance from said central transducer equivalent to introducing a delay equal to 1/B between the respective centers thereof, n/m being substantially equal to 1/2 (1-a/1+a) where m and n are both odd or both even.
Claim 6
Dependent Claim
230 words
A surface wave transducer adapted to provide cosine-on-a-pedestal weighting over a bandwidth B having a mean frequency, fo, where the peak of the cosine-on-a-pedestal function is normalized at 1 and the lowest points thereof and designated a whereby a is greater than zero and less than one, said surface wave transducer comprising: a. means for providing a piezoelectric substrate; b. first and second spaced parallel longitudinal electrical pads disposed coextensively on said substrate; c. means including (m+1) finger-shaped electrodes of a predetermined length spaced one-half wavelength, at said frequency, fo, along said substrate and connected to said first and second electrical pads for providing a central electro-acoustic transducer having m sources where m is a positive integer no less than three; and d. means disposed on opposite sides of said central electro-acoustic transducer each including no more than (n+1) finger-shaped electrodes of said predetermined length spaced one-half wavelength at said frequency, fo, along said substrate and connected to said first and second electrical pads for providing first and second electro-acoustic transducers each having n sources where n is a positive integer no less than one, said first and second electro-acoustic transducers being spaced a predetermined distance from said central transducer equivalent to introducing a delay equal to 1/B between the respective centers thereof, n/m being substantially equal to 1/2 (1-a/1+a) where m and n are both odd or both even.
Claim 7
Dependent Claim
18 words
The surface wave transducer as defined in claim 4 wherein the quantity fo/Bm is no less than one.
Claim 8
Dependent Claim
23 words
The surface wave transducer as defined in claim 4 wherein 1/2 (1-a/1+a) about 0.42 and the quantity fo/Bm is no less than one.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |