US3701154A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Matched filter
Assignee: United States Department of the Navy
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Filing: 1971-03-09
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Granted: 1972-10-24
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Expires: 1991-03-09
Abstract
Abstract A matched filter having a frequency band signal input which is coupled through a wide band filter, through a plurality of narrow band filters coextensive in frequency with the wide band filter to phase code and decode the signal, through a similar number of hard limiters or comparators to an adder, and through a band pass filter, all between transmit-receive (T-R) switches of an electromagnetic echo ranging target detection system to detect targets in noise interference and countermeasure environments.
Inventors
- 👤 Edward J Mckinney
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:38
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/06; G01S13/08; G01S13/10; G01S13/106; G01S13/26; G01S13/28; G01S13/284; G01S13/288
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
309 words
A counter-countermeasure matched filter circuit comprising: an input of freqUency signals from a T-R switch coupled for alternate switching to a transmitter pulse generator and to a receiver output; a wide band filter in said input to pass frequency signals in a predetermined band of frequencies to an output thereof; a plurality of narrow band filters coupled in common to the wide band filter output and each having an output; a two state phase shifter coupled to the output of each narrow band filter for selectively shifting the phase of each narrow band of frequency 0* and 180* on an output thereof providing phase coding and decoding of said wide band of frequencies; a limiter coupled to the output of each narrow band filter to limit the amplitude of the narrow band frequency on an output thereof; an adder network having inputs coupled to the outputs of said limiters to sum the narrow band frequency signals into a wide band of frequencies coextensive in bandwidth to said wide band filter on an output thereof, each circuited narrow band filter, phase shifter, hard limiter, and adder network providing narrow band filter channels; and a band pass filter coupled to the output of said adder circuit to filter out harmonics produced by the addition of said narrow bands of frequencies with an output coupled through said T-R switch to switch for transmission and reception, said switch for transmission being through a hard limiter and gate and said switch for reception being through a linear matched filter to a point of use whereby transmitted frequency signals are phase coded in said plurality of narrow band filters in a plurality of narrow frequency bands and the received echo signals are phase decoded in said plurality of narrow band filters to eliminate false alarms and countermeasure signals not conforming to the frequency coded signals.
Claim 2
Dependent Claim
309 words
A counter-countermeasure matched filter circuit comprising: an input of freqUency signals from a T-R switch coupled for alternate switching to a transmitter pulse generator and to a receiver output; a wide band filter in said input to pass frequency signals in a predetermined band of frequencies to an output thereof; a plurality of narrow band filters coupled in common to the wide band filter output and each having an output; a two state phase shifter coupled to the output of each narrow band filter for selectively shifting the phase of each narrow band of frequency 0* and 180* on an output thereof providing phase coding and decoding of said wide band of frequencies; a limiter coupled to the output of each narrow band filter to limit the amplitude of the narrow band frequency on an output thereof; an adder network having inputs coupled to the outputs of said limiters to sum the narrow band frequency signals into a wide band of frequencies coextensive in bandwidth to said wide band filter on an output thereof, each circuited narrow band filter, phase shifter, hard limiter, and adder network providing narrow band filter channels; and a band pass filter coupled to the output of said adder circuit to filter out harmonics produced by the addition of said narrow bands of frequencies with an output coupled through said T-R switch to switch for transmission and reception, said switch for transmission being through a hard limiter and gate and said switch for reception being through a linear matched filter to a point of use whereby transmitted frequency signals are phase coded in said plurality of narrow band filters in a plurality of narrow frequency bands and the received echo signals are phase decoded in said plurality of narrow band filters to eliminate false alarms and countermeasure signals not conforming to the frequency coded signals.
Claim 3
Dependent Claim
71 words
A counter-countermeasure matched filter circuit as set forth in claim 1 wherein said T-R switch in one switched condition couples said pulse generator output through said filter channels, through said hard limiter, and through said gate for phase coded transmission of pulses, and in the other switched condition couples the receiver through said filter channels for phase decoding the echo pulses and through the linear matched filter for target echo use.
Claim 4
Dependent Claim
52 words
A counter-countermeasure matched filter circuit as set forth in claim 2 wherein said plurality of narrow band filters have separate adjacent narrow frequency bands within the frequency limits of said wide band filter, said narrow frequency bands ranging from contiguous to noncontiguous gaps in frequency therebetween to control the effects of reverberation.
References Cited (Backward Citations)
US3112452A
Cited
US3302162A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |