US3603996A
Expired / Lapsed
US
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Means and method for detecting doppler signals submerged in clutter
Assignee: General Dynamics Corp
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Filing: 1968-08-09
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Granted: 1971-09-07
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Expires: 1988-08-09
Abstract
Abstract A subclutter, personnel detection coherent pulsed doppler radar system for discerning doppler signals submerged in clutter incorporating range gating, clutter rejection and clutter cancellation for use in a highly foliated environment, the received returns gated to eliminate all but those from the surveillance bin at a preselected range, the antenna pattern shaping the resolution cell in both azimuth and elevation. A filter system limits undesired received signals, the passed signal being separated into separate channels for receding or approaching targets, the outputs of the channels being subtracted and then integrated. Since foliage movement is fixed but pliable, the received clutter signal therefrom will integrate to zero voltage level, while with signals received from a target exhibiting continuous radial motion, the doppler signal will integrate to a level which may be displayed or recorded.
Inventors
- 👤 Jerre M Murchison
- 👤 Alexander G Antonio
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 11:01
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/52; G01S13/522; G01S13/524; G01S13/5244
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
59 words
A system for detecting doppler signals submerged in clutter, comprising: A. means generating energy; B. means transmitting energy; C. means receiving echo energy from approaching and receding targets containing doppler information; D. means simultaneously processing the doppler spectrum from the approaching and receding targets contained in the received echo energy to produce a signal proportional to net target motion.
Claim 2
Independent Claim
59 words
A system for detecting doppler signals submerged in clutter, comprising: A. means generating energy; B. means transmitting energy; C. means receiving echo energy from approaching and receding targets containing doppler information; D. means simultaneously processing the doppler spectrum from the approaching and receding targets contained in the received echo energy to produce a signal proportional to net target motion.
Claim 3
Dependent Claim
24 words
means cancelling the doppler spectrum of equal but opposite sense contained in the received echo to produce a signal proportional to net target motion.
Claim 4
Dependent Claim
24 words
means cancelling the doppler spectrum of equal but opposite sense contained in the received echo to produce a signal proportional to net target motion.
Claim 5
Dependent Claim
22 words
The system defined by claim 1 wherein: A. said energy generating means produces coherent RF energy; and B. said processing means comprises:
Claim 6
Dependent Claim
21 words
timing means establishing the pulse repetition frequency for said transmitting means and the range gate timing pulse for said receiving means;
Claim 7
Dependent Claim
21 words
timing means establishing the pulse repetition frequency for said transmitting means and the range gate timing pulse for said receiving means;
Claim 8
Dependent Claim
34 words
plural high pass filters, a detector detecting any signal passed by each said high pass filter, and a log ratio amplifier operative to cause the doppler spectrum in each sideband to be velocity weighted;
Claim 9
Dependent Claim
34 words
plural high pass filters, a detector detecting any signal passed by each said high pass filter, and a log ratio amplifier operative to cause the doppler spectrum in each sideband to be velocity weighted;
Claim 10
Dependent Claim
72 words
a canceler means processing the passed signal from said extracting means to produce a signal proportional to net target motion, and comprising: a. means separating the upper and lower sidebands, said means controlled by said clock means; b. means detecting and determinating the inequality of the separated sidebands; c. means integrating the detected signal with respect to time to provide a signal indicating presence, location and direction of motion of the target.
Claim 11
Dependent Claim
72 words
a canceler means processing the passed signal from said extracting means to produce a signal proportional to net target motion, and comprising: a. means separating the upper and lower sidebands, said means controlled by said clock means; b. means detecting and determinating the inequality of the separated sidebands; c. means integrating the detected signal with respect to time to provide a signal indicating presence, location and direction of motion of the target.
Claim 12
Dependent Claim
13 words
a range gate gated by the timing pulse from said range gate generator;
Claim 13
Dependent Claim
13 words
a range gate gated by the timing pulse from said range gate generator;
Claim 14
Dependent Claim
27 words
a timer means comprising a pulse repetition frequency generator and a range gate generator providing the timing pulse for a range gate in said receiver means; and
Claim 15
Dependent Claim
27 words
a timer means comprising a pulse repetition frequency generator and a range gate generator providing the timing pulse for a range gate in said receiver means; and
Claim 16
Dependent Claim
19 words
a phase detector using the phase detector reference signal from said synthesizer and producing a modulated, bipolar video signal;
Claim 17
Dependent Claim
19 words
a phase detector using the phase detector reference signal from said synthesizer and producing a modulated, bipolar video signal;
Claim 18
Dependent Claim
58 words
clock means providing filter and canceler reference signals; B. said transmitter means comprises means to gate and amplify the continuous wave transmitter signal at the pulse repetition frequency established by said timer; C. said echo energy receiving means converts the returned RF energy to an IF signal retaining all doppler information contained in the return signal, and comprising
Claim 19
Dependent Claim
58 words
clock means providing filter and canceler reference signals; B. said transmitter means comprises means to gate and amplify the continuous wave transmitter signal at the pulse repetition frequency established by said timer; C. said echo energy receiving means converts the returned RF energy to an IF signal retaining all doppler information contained in the return signal, and comprising
Claim 20
Dependent Claim
31 words
an integrator operative to integrate the sideband with respect to time so that the output will be proportional to the summation of the cross section of all targets and their displacement.
Claim 21
Dependent Claim
31 words
an integrator operative to integrate the sideband with respect to time so that the output will be proportional to the summation of the cross section of all targets and their displacement.
Claim 22
Dependent Claim
141 words
clock means providing basic coherent signals for said synthesizer means, said doppler spectrum extracting means and said cancelling means; B. said transmitting means having gating and amplifying means responsive to said timing means operative to establish the transmitted pulse of the coherent signal from said synchronizer means; C. said echo receiving means converting the returned RF signal to a modulated, bipolar video signal retaining all doppler information of the RF echo signal, stretching the video pulses in time to cover the entire pulse repetition period emphasizing the fundamental of the modulation frequency and eliminating harmonics of the timing means pulse repetition frequency; D. said doppler spectrum extracting means rejecting stationary target return signals received from said receiving means and passing target return signals exhibiting a doppler shift, the extracting reference frequency established by a basic coherent signal from said clock means.
Claim 23
Dependent Claim
141 words
clock means providing basic coherent signals for said synthesizer means, said doppler spectrum extracting means and said cancelling means; B. said transmitting means having gating and amplifying means responsive to said timing means operative to establish the transmitted pulse of the coherent signal from said synchronizer means; C. said echo receiving means converting the returned RF signal to a modulated, bipolar video signal retaining all doppler information of the RF echo signal, stretching the video pulses in time to cover the entire pulse repetition period emphasizing the fundamental of the modulation frequency and eliminating harmonics of the timing means pulse repetition frequency; D. said doppler spectrum extracting means rejecting stationary target return signals received from said receiving means and passing target return signals exhibiting a doppler shift, the extracting reference frequency established by a basic coherent signal from said clock means.
Claim 24
Dependent Claim
43 words
The system defined by claim 2 wherein said cancelling means comprises: A. means separating the upper and lower sidebands of the doppler spectrum; B. means operative to cause the separated sidebands to be detected and integrated and operative to readout any resultant signal.
Claim 25
Dependent Claim
17 words
The system defined by claim 3 wherein: A. said generating means produces pulsed RF energy and comprises:
Claim 26
Dependent Claim
24 words
a boxcar generator operative to stretch the video signal in time to cover substantially the entire pulse repetition period; D. said processing means comprises:
Claim 27
Dependent Claim
24 words
a boxcar generator operative to stretch the video signal in time to cover substantially the entire pulse repetition period; D. said processing means comprises:
Claim 28
Dependent Claim
62 words
The system defined by claim 4 wherein said means separating the sidebands of the doppler spectrum are controlled by said clock means to maintain the center frequency of said sideband separating means an absolute value on either side of a reference frequency, and said detection and integration means includes means which indicates if the summation over the integration period is not zero.
Claim 29
Dependent Claim
64 words
The system defined by claim 4 wherein said means separating the sidebands of the doppler spectrum are controlled by said clock means, means velocity weighting each sideband and said detection and integration means includes means integrating the velocity weighted sideband Spectrum with respect to time so that the output is proportional to the summation of the cross section of all targets and their displacement.
Claim 30
Dependent Claim
18 words
The device defined by claim 1 wherein: A. said generating means produces pulsed, coherent RF energy and comprises:
Claim 31
Dependent Claim
13 words
The detection device defined by claim 7 wherein: A. said canceler means comprises:
Claim 32
Dependent Claim
108 words
The detection device defined by claim 7 wherein: said canceler means comprises: A. plural narrow band-pass digital filters for receiving the signal passed by said doppler spectrum filter means dependent on the relative magnitude of the passed signal; the center frequency of the said digital filters controlled and established by said clock means; B. detector and integrator means for each said digital filter detecting and integrating the outputs of said digital filters; C. a summation amplifier summing the signal output of said detector and integration means; and D. readout means responsive to any signal from said summation amplifier which is larger, in either sEnse, than a preselected value.
Claim 33
Dependent Claim
98 words
In a system detecting amplitude and frequency of a returned signal containing doppler information, the means for cancelling signal information resulting from fixed but pliable movement while retaining that resultant from continuous radial motion, comprising: A. means separating the sidebands of the returned doppler information containing signal; B. means detecting and integrating the separated sidebands to produce a signal proportional to net target motion; C. clock means establishing and controlling the center frequency of said sideband separating means to maintain the center frequency of said sideband separating means an absolute value on either side of the center frequency.
Claim 34
Dependent Claim
98 words
In a system detecting amplitude and frequency of a returned signal containing doppler information, the means for cancelling signal information resulting from fixed but pliable movement while retaining that resultant from continuous radial motion, comprising: A. means separating the sidebands of the returned doppler information containing signal; B. means detecting and integrating the separated sidebands to produce a signal proportional to net target motion; C. clock means establishing and controlling the center frequency of said sideband separating means to maintain the center frequency of said sideband separating means an absolute value on either side of the center frequency.
Claim 35
Dependent Claim
27 words
The means defined by claim 10 including a filter means having a filter center frequency established and controlled by said clock means rejecting stationary target return signals.
Claim 36
Independent Claim
162 words
The method of detecting in a target area an object having continuous radial motion which is obscured by objects exhibiting fixed but pliable movement comprising: A. detecting the amplitude and frequency of a returned signal containing doppler information from the target area; B. separating the sidebands of the detected return signal by establishing a center reference frequency so that the sidebands represent a function of the amplitude of all targets exhibiting motion versus frequency; C. velocity weighting the doppler spectrum in each separated sideband; D. integrating the spectrum with respect to time to obtain a signal which is proportional to the summation of the cross section and displacement of all target signals exhibiting a doppler shift so that the summation of the two sidebands will cancel to a predictable level over the integration period where objects in the target area are fixed but pliable but where objects exhibit continuous radial motion the signal return will add only to one of the sidebands.
Claim 37
Independent Claim
162 words
The method of detecting in a target area an object having continuous radial motion which is obscured by objects exhibiting fixed but pliable movement comprising: A. detecting the amplitude and frequency of a returned signal containing doppler information from the target area; B. separating the sidebands of the detected return signal by establishing a center reference frequency so that the sidebands represent a function of the amplitude of all targets exhibiting motion versus frequency; C. velocity weighting the doppler spectrum in each separated sideband; D. integrating the spectrum with respect to time to obtain a signal which is proportional to the summation of the cross section and displacement of all target signals exhibiting a doppler shift so that the summation of the two sidebands will cancel to a predictable level over the integration period where objects in the target area are fixed but pliable but where objects exhibit continuous radial motion the signal return will add only to one of the sidebands.
Claim 38
Dependent Claim
29 words
The method defined by claim 12, including the additional step prior to separating the sidebands of filtering the returned signal to remove any signal not exhibiting a doppler shift.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-06 | 1975-03-08 | 1975-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-06 | 1979-03-08 | 1979-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-06 | 1983-03-08 | 1983-09-07 | $7700.00 | Window Closed / Lapsed |