US4809002A
Expired / Lapsed
US
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Moving target indicator
Assignee: NEC Corp
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Filing: 1985-02-13
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Granted: 1989-02-28
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Expires: 2005-02-13
Abstract
Abstract A moving target indicator device comprising a first clutter removing circuit for responding to a radar having a variable transmit repetition time and for removing clutter having a Doppler speed of nearly zero from a radar received signal having stationary clutter and moving clutter. The device further includes a correction circuit to keep the amplitude components and the phase components of the first clutter removing circuit output substantially constant. A second clutter removing circuit removes clutter having a constant amplitude component and phase component from the output of the correction circuit.
Inventors
- 👤 Fusaji Togashi
- 👤 Toshihiko Hagisawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:37
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/52; G01S13/522; G01S13/524; G01S13/5244; G01S13/526; G01S13/528
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
125 words
A moving target indicator apparatus for removing stationary and moving clutter from a radar received signal received in response to a transmitted signal having a varied transmit repetition time comprising: a first clutter removing means for removing stationary clutter from said radar received signal and generating a first signal having varying amplitude and phase cmponents; a correction means responsive to said first clutter removing means for correcting the moving clutter of said first signal having varying amplitude and phase components and producing a corrected signal having a constant amplitude and a constant phase based upon the varied transmit repetition time; and a second clutter removing means responsive to said correction means for removing the moving clutter from said corrected signal and generating a second signal.
Claim 2
Dependent Claim
125 words
A moving target indicator apparatus for removing stationary and moving clutter from a radar received signal received in response to a transmitted signal having a varied transmit repetition time comprising: a first clutter removing means for removing stationary clutter from said radar received signal and generating a first signal having varying amplitude and phase cmponents; a correction means responsive to said first clutter removing means for correcting the moving clutter of said first signal having varying amplitude and phase components and producing a corrected signal having a constant amplitude and a constant phase based upon the varied transmit repetition time; and a second clutter removing means responsive to said correction means for removing the moving clutter from said corrected signal and generating a second signal.
Claim 3
Dependent Claim
15 words
The apparatus of claim 1, further comprising a display means for displaying said second signal.
Claim 4
Dependent Claim
120 words
The apparatus of claim 1, wherein said first clutter removing means comprises a means for removing the stationary clutter from an in-phase component of said radar received signal and a means for removing the stationary clutter from a quadrature component of said radar received signal; said correction means comprises a means for correcting an in-phase component of said first signal and a means for correcting a quadrature component of said first signal; and said second clutter removing means comprises a means, producing a first output signal, for removing the moving clutter from an in-phase component of said corrected signal and a means, producing a second output signal, for removing the moving clutter from a quadrature component of said corrected signal.
Claim 5
Dependent Claim
20 words
The apparatus according claim 3, further comprising combination means for combining said first output signal and said second output signal.
Claim 6
Dependent Claim
74 words
The apparatus according to claim 1, wherein said correction means comprises; phase-correcting means for generating a phase variation signal Δθ each repetition time of a radar trigger; amplitude-correcting means for generating an amplitude-correcting data signal B each repetition time for adjusting an amplitude variation of said first signal; and integrator means for integrating said phase variation signal Δθ and outputting an integrated phase variation signal ΣΔθ as a reference data signal for phase correction.
Claim 7
Dependent Claim
44 words
The apparatus according to claim 5, further comprising converter means for generating a sine component and a cosine component of said integrated value signal ΣΔθ; and correcting data generator means, responsive to said converter means and said amplitude correcting means, for generating correction data.
Claim 8
Dependent Claim
29 words
The apparatus according to claim 5 further comprising presumptive Doppler frequency generator means for outputting a presumptive Doppler frequency signal fd, within a predetermined range, to said phase-correcting means.
Claim 9
Dependent Claim
22 words
The apparatus according to claim 7, wherein said presumptive Doppler frequency generator means is connected to an input of said amplitude-correcting means.
Claim 10
Dependent Claim
33 words
The apparatus according to claim 5, wherein said amplitude-correcting data signal B is a function of the average Doppler frequency of said moving clutter, the trigger repetition time, and the present trigger time.
Claim 11
Dependent Claim
51 words
The apparatus according to claim 1, wherein said correction means comprises a means for detecting a phase-shift, of said radar received signal, between successive repetition times; and a means for generating an average Doppler phase-shift signal Δθ wherein phase components of said first signal are corrected in response to said average.
Claim 12
Dependent Claim
38 words
The apparatus according to claim 1, wherein said correction means comprises a means for determining an average amplitude value A of said first signal; and a means for generating an amplitude correction signal inversely proportional to said average.
Claim 13
Dependent Claim
26 words
The apparatus of claim 7, wherein said Doppler frequency generator means further comprises a means for adjusting said Doppler frequency signal fd to a fixed value.
Claim 14
Dependent Claim
19 words
The apparatus of claim 10, wherein amplitude components of said first signal are corrected in response to said average.
Claim 15
Dependent Claim
24 words
The apparatus of claim 5, wherein said phase-correcting signal corresponds to an average Doppler frequency fd related to the velocity of said moving clutter.
Claim 16
Independent Claim
87 words
A method for removing stationary and moving clutter from a radar received signal received in response to a transmitted signal having a varied transmit repetition time, comprising the steps of: (a) removing stationary clutter from said signal to produce a stationary clutter-free signal having varying amplitude and phase components; (b) adjusting the moving clutter of said stationary clutter-free signal to obtain a corrected signal having constant phase and constant amplitude based upon the varied transmit repetition time; and (c) removing the moving clutter from said corrected signal.
Claim 17
Independent Claim
87 words
A method for removing stationary and moving clutter from a radar received signal received in response to a transmitted signal having a varied transmit repetition time, comprising the steps of: (a) removing stationary clutter from said signal to produce a stationary clutter-free signal having varying amplitude and phase components; (b) adjusting the moving clutter of said stationary clutter-free signal to obtain a corrected signal having constant phase and constant amplitude based upon the varied transmit repetition time; and (c) removing the moving clutter from said corrected signal.
Claim 18
Dependent Claim
39 words
The method of claim 15, wherein said step of removing stationary clutter comprises: (a) separating said received signal into an in-phase component and a quadrature component; and (b) removing stationary clutter from said in-phase component and said quadrature component.
Claim 19
Dependent Claim
44 words
The method of claim 16, wherein said step of adjusting the moving clutter of said stationary clutter-free signal comprises adjusting said in-phase component to have a constant phase and constant amplitude and adjusting said quadrature component to have a constant phase and constant amplitude.
Claim 20
Dependent Claim
34 words
The method of claim 17, wherein said step of removing moving clutter comprises removing moving clutter from said in-phase component of said signal and removing moving clutter from said quadrature component of said signal.
Claim 21
Dependent Claim
18 words
The method of claim 18, further comprising the step of combining said in-phase component and said quadrature component.
Claim 22
Dependent Claim
67 words
The method of claim 15, wherein the step of adjusting the moving clutter of said stationary clutter-free signal comprises: (i) generating a phase variation signal each transmit repetition time; (ii) generating an amplitude correcting signal each transmit repetition time; (iii) integrating said phase variation signal; and (iv) adjusting the moving clutter of said stationary clutter-free signal in response to said integrated signal and said amplitude correcting signal.
Claim 23
Independent Claim
22 words
The method 20, wherein said phase variation signal corresponds to an average Doppler frequency related to the velocity of said moving clutter.
Claim 24
Independent Claim
22 words
The method 20, wherein said phase variation signal corresponds to an average Doppler frequency related to the velocity of said moving clutter.
Claim 25
Dependent Claim
67 words
The method of claim 20, wherein the step of adjusting the moving clutter of said stationary clutter-free signal in response to said integrated signal and said amplitude correcting signal comprises: (a') generating a sine component and a cosine component of said integrated signal; (b') adjusting the moving clutter of said stationary clutter-free signal in response to said sine component, said cosine component, and said amplitude correcting signal.
Claim 26
Dependent Claim
55 words
The method of claim 15, wherein said step of adjusting the moving clutter of said stationary clutter-free signal comprises: (i) detecting a phase shift of said radar signal between successive repetition times; (ii) calculating an average Doppler phase shift; and (iii) adjusting the moving clutter of said stationary clutter-free signal in response to said average.
Claim 27
Dependent Claim
58 words
The method of claim 15, wherein said step of adjusting the moving clutter of said stationary clutter-free signal comprises: (i) calculating an average amplitude of said stationary clutter-free signal; (ii) generating an amplitude correction signal inversely proportional to said average; and (iii) adjusting the moving clutter of said stationary clutter-free signal in response to said amplitude correction 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) | 1992-02-28 | 1992-08-29 | 1993-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-28 | 1996-08-29 | 1997-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-28 | 2000-08-29 | 2001-02-28 | $7700.00 | Window Closed / Lapsed |