US4459592A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods of and circuits for suppressing doppler radar clutter
Assignee: Individual
•
Filing: 1981-06-24
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Granted: 1984-07-10
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Expires: 2001-06-24
Abstract
Abstract Clutter suppressors and methods of clutter suppression for radars which employ the doppler effect for enhancing signals due to moving targets relative to signals due to clutter caused land, sea or rain. Specifically, the disclosure concerns suppressors and methods of clutter suppression for cw doppler, pulse doppler and MTI (moving target indication) radars. The suppressors reduce the occurrence of radar output due to clutter by permitting and prohibiting radar output on the basis of the relative strength of signals that contain doppler frequency components of the radar echo.
Inventors
- 👤 Maurice W. Long
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:41
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/52; G01S13/522; G01S13/524
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
175 words
A radar clutter suppressor comprising: receiving means for receiving radar echoes of radar transmitter waves and for providing a received signal with doppler frequency components in response to said radar echoes; signal processing means having doppler processor means for frequency filtering the received signal to selectively attenuate the doppler frequency components of the received signal and provide at least one filtered signal in response to the received signal; amplitude comparison means for comparing the at least one filtered signal and the received signal and for providing a comparator output signal of a first level only when a ratio of the strengths of the at least one filtered signal and the received signal is within a predetermined range of values and of a second level whenever the ratio is outside the predetermined range of values; and gating means responsive to the comparator output signal for selectively passing a radar output signal constituting a clutter suppressed radar output only when the ratio of the at least one filtered signal to the received signal exceeds a predetermined value.
Claim 2
Dependent Claim
175 words
A radar clutter suppressor comprising: receiving means for receiving radar echoes of radar transmitter waves and for providing a received signal with doppler frequency components in response to said radar echoes; signal processing means having doppler processor means for frequency filtering the received signal to selectively attenuate the doppler frequency components of the received signal and provide at least one filtered signal in response to the received signal; amplitude comparison means for comparing the at least one filtered signal and the received signal and for providing a comparator output signal of a first level only when a ratio of the strengths of the at least one filtered signal and the received signal is within a predetermined range of values and of a second level whenever the ratio is outside the predetermined range of values; and gating means responsive to the comparator output signal for selectively passing a radar output signal constituting a clutter suppressed radar output only when the ratio of the at least one filtered signal to the received signal exceeds a predetermined value.
Claim 3
Dependent Claim
187 words
A radar clutter suppressor comprising: receiving means for receiving radar echoes of radar transmitter waves and for providing a received signal with doppler frequency components in response to said radar echoes; signal processing means having a doppler processor for frequency filtering the received signal to selectively attenuate the doppler frequency components of the received signal and provide at least one filtered signal in response to the received signal; integrating means for providing a reference signal in response to the received signal; amplitude comparison means for comparing the at least one filtered signal and the reference signal to provide a comparator output signal of a first level only when a ratio of the strengths of the at least one filtered signal and the reference signal is within a predetermined range of values and of a second level whenever the ratio is outside the predetermined range of values; and gating means responsive to said comparator output signal for selectively passing a radar output signal constituting a clutter suppressed radar output only when the ratio of the at least one filtered signal to the reference signal exceeds a predetermined value.
Claim 4
Dependent Claim
187 words
A radar clutter suppressor comprising: receiving means for receiving radar echoes of radar transmitter waves and for providing a received signal with doppler frequency components in response to said radar echoes; signal processing means having a doppler processor for frequency filtering the received signal to selectively attenuate the doppler frequency components of the received signal and provide at least one filtered signal in response to the received signal; integrating means for providing a reference signal in response to the received signal; amplitude comparison means for comparing the at least one filtered signal and the reference signal to provide a comparator output signal of a first level only when a ratio of the strengths of the at least one filtered signal and the reference signal is within a predetermined range of values and of a second level whenever the ratio is outside the predetermined range of values; and gating means responsive to said comparator output signal for selectively passing a radar output signal constituting a clutter suppressed radar output only when the ratio of the at least one filtered signal to the reference signal exceeds a predetermined value.
Claim 5
Dependent Claim
23 words
A radar clutter suppressor according to claim 1 or claim 2, wherein said gating means selectively passes the at least one filtered signal.
Claim 6
Dependent Claim
18 words
A radar clutter suppressor according to claim 1 or claim 2, wherein the transmitter waves are continuous waves.
Claim 7
Dependent Claim
18 words
A radar clutter suppressor according to claim 1 or claim 2, wherein the transmitter waves are pulsed waves.
Claim 8
Dependent Claim
19 words
A radar clutter suppressor according to claim 1 or claim 2, wherein said signal processing means includes CFAR circuitry.
Claim 9
Dependent Claim
21 words
A radar clutter suppressor according to claim 1 or claim 2, wherein said doppler processor is comprised of a MTI canceler.
Claim 10
Dependent Claim
23 words
A radar clutter suppressor according to claim 1 or claim 2, wherein said doppler processor is comprised of at least one bandpass filter.
Claim 11
Dependent Claim
34 words
A radar clutter suppressor according to claim 2, wherein said doppler processor is comprised of a transversal time dependent filter bank and said integrating means is a zero frequency filter of said filter bank.
Claim 12
Dependent Claim
25 words
A radar clutter suppressor according to claim 1 or claim 2, wherein said doppler processor includes a MTI canceler and at least one bandpass filter.
Claim 13
Dependent Claim
21 words
A radar clutter suppressor according to claim 1 or claim 2, wherein said signal processing means is comprised of integrating means.
Claim 14
Dependent Claim
22 words
A radar clutter suppressor according to claim 1 or claim 2, wherein said signal processing means is comprised of lowpass filter means.
Claim 15
Dependent Claim
19 words
A radar clutter suppressor according to claim 1 or claim 2, wherein said receiving means includes a scanning antenna.
Claim 16
Independent Claim
140 words
A method of suppressing radar clutter comprising the steps of: providing a received signal with doppler frequency components in response to radar echoes of radar transmitted waves; providing at least one filtered signal by a step that includes selectively attenuating the doppler frequency components of said received signal; comparing strengths of the said received signal and said at least one filtered signal and providing a comparator output signal of a first level only when a ratio of said strengths is within a first predetermined range of values and of a second level whenever said ratio is outside said predetermined range of values; and gating a signal in response to the comparator output signal to provide a gated signal constituting a clutter suppressed radar output only when the ratio of said filtered signal to said received signal exceeds a predetermined value.
Claim 17
Independent Claim
140 words
A method of suppressing radar clutter comprising the steps of: providing a received signal with doppler frequency components in response to radar echoes of radar transmitted waves; providing at least one filtered signal by a step that includes selectively attenuating the doppler frequency components of said received signal; comparing strengths of the said received signal and said at least one filtered signal and providing a comparator output signal of a first level only when a ratio of said strengths is within a first predetermined range of values and of a second level whenever said ratio is outside said predetermined range of values; and gating a signal in response to the comparator output signal to provide a gated signal constituting a clutter suppressed radar output only when the ratio of said filtered signal to said received signal exceeds a predetermined value.
Claim 18
Independent Claim
152 words
A method of suppressing radar clutter comprising the steps of: providing a received signal with doppler frequency components in response to radar echoes of radar transmitted waves; providing at least one filtered signal by a step that includes selectively attenuating the doppler frequency components of said received signal; integrating said received signal for providing a reference signal; comparing strengths of the said reference signal and said at least one filtered signal and providing a comparator output signal of a first level only when a ratio of said strengths is within a first predetermined range of values and of a second level whenever said ratio is outside said predetermined range of values; and gating a signal in response to the comparator output signal to provide a gated signal constituting a clutter suppressed radar output only when the ratio of said at least one filtered signal to said reference signal exceeds a predetermined value.
Claim 19
Independent Claim
152 words
A method of suppressing radar clutter comprising the steps of: providing a received signal with doppler frequency components in response to radar echoes of radar transmitted waves; providing at least one filtered signal by a step that includes selectively attenuating the doppler frequency components of said received signal; integrating said received signal for providing a reference signal; comparing strengths of the said reference signal and said at least one filtered signal and providing a comparator output signal of a first level only when a ratio of said strengths is within a first predetermined range of values and of a second level whenever said ratio is outside said predetermined range of values; and gating a signal in response to the comparator output signal to provide a gated signal constituting a clutter suppressed radar output only when the ratio of said at least one filtered signal to said reference signal exceeds a predetermined value.
Claim 20
Dependent Claim
24 words
A method of suppressing radar clutter according to claim 14 or claim 15, wherein said gated signal is said at least one filtered signal.
Claim 21
Dependent Claim
23 words
A method of suppressing radar clutter according to claim 14 or claim 15, wherein said waves from said radar transmitter are continuous waves.
Claim 22
Dependent Claim
23 words
A method of suppressing radar clutter according to claim 14 or claim 15, wherein said waves from said radar transmitter are pulsed waves.
Claim 23
Dependent Claim
48 words
A method of suppressing radar clutter according to claim 14 or claim 15, wherein the step of providing at least one filtered signal includes band reject filtering for providing maximum attenuation for a band of doppler frequency components of said received signal, said band centered at zero frequency.
Claim 24
Dependent Claim
52 words
A method of suppressing radar clutter according to claim 14 or claim 15, wherein the step of providing at least one filtered signal includes band reject filtering for providing maximum attenuation for a band of doppler frequency components of said received signal, said band centered at a positive or a negative frequency.
Claim 25
Dependent Claim
48 words
A method of suppressing radar clutter according to claim 14 or claim 15, wherein the step of providing at least one filtered signal includes bandpass filtering for providing minimum attenuation for a band of doppler frequency components of said received signal, said band not centered at zero frequency.
Claim 26
Dependent Claim
34 words
A method of suppressing radar clutter according to claim 14 or claim 15, wherein the step of providing at least one filtered signal includes integrating said one of said at least one filtered signal.
Claim 27
Dependent Claim
43 words
A method of suppressing radar clutter according to claim 14 or claim 15, wherein the step of providing a received signal including scanning the beam of a radar antenna for providing a directional response to the radar echoes of the radar transmitted waves.
Claim 28
Dependent Claim
120 words
A radar clutter suppressor comprising: MTI Processor means for processing a received signal to provide a MTI canceled signal; a ratio comparator means for comparing strengths of the received signal and the canceled signal to provide a comparator output signal only when a ratio of strengths of the signals exceeds a predetermined value, said ratio comparator means consisting of an attenuator operatively arranged to pass and to attenuate the received signal and an amplitude comparator operatively arranged to receive the canceled signal and output from said attenuator; and a signal processing means including a gate responsive to the comparator output signal for selectively passing the canceled signal whenever the comparator output signal is present, thereby providing clutter suppressed radar output.
Claim 29
Dependent Claim
120 words
A radar clutter suppressor comprising: MTI Processor means for processing a received signal to provide a MTI canceled signal; a ratio comparator means for comparing strengths of the received signal and the canceled signal to provide a comparator output signal only when a ratio of strengths of the signals exceeds a predetermined value, said ratio comparator means consisting of an attenuator operatively arranged to pass and to attenuate the received signal and an amplitude comparator operatively arranged to receive the canceled signal and output from said attenuator; and a signal processing means including a gate responsive to the comparator output signal for selectively passing the canceled signal whenever the comparator output signal is present, thereby providing clutter suppressed radar output.
Claim 30
Dependent Claim
132 words
A radar clutter suppressor comprising: MTI processor means for processing a received signal to provide a MTI canceled signal; a ratio comparator means for comparing strengths of the received signal and the canceled signal to provide a comparator output signal only when a ratio of strengths of the signals exceeds a predetermined value, said ratio comparator means consisting of an attenuator operatively arranged to pass and to attenuate the recieved signal, an amplitude detector operatively arranged to receive output from said attenuator and an amplitude comparator operatively arranged to receive the canceled signal and output from said amplitude detector; and a signal processing means including a gate responsive to the comparator output signal for selectively passing the canceled signal whenever the comparator output signal is present, thereby providing clutter suppressed radar output.
Claim 31
Dependent Claim
132 words
A radar clutter suppressor comprising: MTI processor means for processing a received signal to provide a MTI canceled signal; a ratio comparator means for comparing strengths of the received signal and the canceled signal to provide a comparator output signal only when a ratio of strengths of the signals exceeds a predetermined value, said ratio comparator means consisting of an attenuator operatively arranged to pass and to attenuate the recieved signal, an amplitude detector operatively arranged to receive output from said attenuator and an amplitude comparator operatively arranged to receive the canceled signal and output from said amplitude detector; and a signal processing means including a gate responsive to the comparator output signal for selectively passing the canceled signal whenever the comparator output signal is present, thereby providing clutter suppressed radar output.
Claim 32
Dependent Claim
39 words
A radar clutter suppressor according to claim 25, wherein said MTI processor means includes a phase detector having one input means coupled to receive the received signal and a second input means coupled to receive a phase reference signal.
Claim 33
Dependent Claim
21 words
A radar clutter suppressor according to claim 26, including means for supplying the phase reference signal as a variable reference signal.
Claim 34
Independent Claim
145 words
A method of suppressing radar clutter comprising the steps of: a. providing pulsed transmitted waves; b. providing a first received signal receptive to doppler frequencies of radar echoes due to the pulsed transmitted waves and thereby providing a first received signal which includes a range of doppler frequencies; c. providing delayed signals by delaying the first received signal; d. providing a second signal by selectively attenuating doppler frequencies of the first received signal by combining said first received and said delayed signals; e. attenuating said first signal and thereby providing a third signal; f. comparing strengths of the second and the third signals and providing a first output signal when a ratio of the strengths exceeds a predetermined value; and g. gating the second signal only in the presence of the first output signal to provide a gated signal constituting a clutter suppressed radar output.
Claim 35
Independent Claim
145 words
A method of suppressing radar clutter comprising the steps of: a. providing pulsed transmitted waves; b. providing a first received signal receptive to doppler frequencies of radar echoes due to the pulsed transmitted waves and thereby providing a first received signal which includes a range of doppler frequencies; c. providing delayed signals by delaying the first received signal; d. providing a second signal by selectively attenuating doppler frequencies of the first received signal by combining said first received and said delayed signals; e. attenuating said first signal and thereby providing a third signal; f. comparing strengths of the second and the third signals and providing a first output signal when a ratio of the strengths exceeds a predetermined value; and g. gating the second signal only in the presence of the first output signal to provide a gated signal constituting a clutter suppressed radar output.
Claim 36
Dependent Claim
32 words
A method of suppressing clutter according to claim 28, whereby high attenuation is provided for a band of doppler frequencies, said band centered at zero doppler frequency, for producing the second signal.
Claim 37
Dependent Claim
34 words
A method of suppressing clutter according to claim 29, whereby high attenuation is provided for a band of doppler frequencies, said band centered at a positive or negative frequency, for producing the second signal.
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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) | 1987-07-10 | 1988-01-09 | 1988-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-10 | 1992-01-09 | 1992-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-10 | 1996-01-09 | 1996-07-10 | $7700.00 | Window Closed / Lapsed |