Patent US5001091A successfully refreshed from Google Patents.
Patent EP0069415A1 successfully refreshed from Google Patents.
EP0069415A1
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EP
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Moving target indicator (MTI) processing unit for radar apparatus
Assignee: Thales Nederland BV
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Filing: 1982-06-16
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Granted: —
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Expires: 2002-06-16
Abstract
Abstract Search radar apparatus containing an MTI video processing unit provided with: a canceller (2) for generating video signals of moving targets; a zero-velocity filter (3) for generating clutter video signals; a conditional circuit (4) connected to the canceller (2) and the filter (3) for generating per range quant of each radar scan a clutter switching signal if for the range quant the signal value obtained with filter (3) is greater than the signal value obtained with the canceller (2); a combination circuit (95) connected to said filter (3) and the conditional circuit (4) for selecting the clutter video signals present with the clutter switching signals and for determining therefrom a temporary clutter level in each clutter cell and each antenna revolution period; and clutter level indication means (94) connected to the combination circuit (95) for determining a standard clutter level per range-azimuth clutter cell of the radar range with the application of clutter video signals.
Inventors
- 👤 Willem Andries Hol
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 12:31
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/52; G01S13/522; G01S13/524; G01S13/5248; G01S13/538
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
184 words
Search radar apparatus containing an MTI video processing unit provided with a canceller (2) for generating video signals of moving targets, a zero-velocity filter (3) for generating clutter video signals, and clutter level indication means (94) for determining a standard clutter level per range-azimuth clutter cell of the radar range with the application of clutter video signals, characterised in that .the MTI video processing unit comprises a conditional circuit (4) connected to the canceller and the zero-velocity filter for generating per range quant of each radar scan a clutter switching signal if for the range quant the signal value obtained with the zero-velocity filter (3) is greater than the signal value obtained with the canceller (2), and further comprises a combination circuit (95) connected to the zero-velocity filter (3) and the conditional circuit (4) for selecting the clutter video signals present with the clutter switching signals and for determining from the thus selected clutter video signals a temporary clutter level in each clutter cell ana each antenna revolution period for application to the clutter level indication means p4) to produce a standard clutter level.
Claim 2
Dependent Claim
184 words
Search radar apparatus containing an MTI video processing unit provided with a canceller (2) for generating video signals of moving targets, a zero-velocity filter (3) for generating clutter video signals, and clutter level indication means (94) for determining a standard clutter level per range-azimuth clutter cell of the radar range with the application of clutter video signals, characterised in that .the MTI video processing unit comprises a conditional circuit (4) connected to the canceller and the zero-velocity filter for generating per range quant of each radar scan a clutter switching signal if for the range quant the signal value obtained with the zero-velocity filter (3) is greater than the signal value obtained with the canceller (2), and further comprises a combination circuit (95) connected to the zero-velocity filter (3) and the conditional circuit (4) for selecting the clutter video signals present with the clutter switching signals and for determining from the thus selected clutter video signals a temporary clutter level in each clutter cell ana each antenna revolution period for application to the clutter level indication means p4) to produce a standard clutter level.
Claim 3
Dependent Claim
46 words
Search radar apparatus as claimed in claim 1, characterised in that the canceller (2) and the zero-velocity filter (3) are designed to function as a linear-phase filter of the transversal type, whereby the weight factors denoted by corresponding numbers are matched to each other in magnitude.
Claim 4
Dependent Claim
72 words
Search radar apparatus as claimed in claim 1, characterised in that the conditional circuit (4) comprises a revaluation circuit (14) connected to the canceller (2) for raising the level of the canceller-supplied video signal, and a comparator (15) for generating a fixed-target indication signal upon receiving simultaneously a clutter signal and a raised video signal to produce a clutter switching signal in the event the clutter signal exceeds the raised video signal.
Claim 5
Dependent Claim
28 words
Search radar apparatus as claimed in claim 3, characterised in that the radar apparatus is designed to generate transmitter pulses with a plurality of staggered pulse repetition times.
Claim 6
Dependent Claim
79 words
Search radar apparatus as claimed in claim 4, characterised in that the conditional circuit (4) comprises first memory means (16) connected to the comparator (15) for storing per range quant the fixed-target indication signals for a period corresponding with a number of successive pulse repetition times, and means (17) for generating the clutter switching signal in the presence of a'defined minimum number of fixed-target indication signals obtained for corresponding range quants within said period in the memory means (16).
Claim 7
Dependent Claim
47 words
Search radar apparatus as claimed in claim 2, characterised in that the number of delay lines of the transversal filter (2, 3) with a delay time attuned to the pulse repetition time, is greater than or equal to the real number of weight factors of the filter.
Claim 8
Dependent Claim
102 words
Search radar apparatus as claimed in claim 1, characterised in that the combination circuit (95) comprises selection means (98) and third memory means (99), which memory means are designed for storing per antenna revolution and per clutter cell the maximum value referred to as temporary clutter level of the clutter signals obtained through the selection means (98), and which selection means (98) are designed for supplying the third memory means (99) with a clutter signal if the level of the latter clutter signal exceeds the pre-generated temporary clutter-level value of the relevant clutter cell in the presence of the clutter switching signal.
Claim 9
Dependent Claim
70 words
Search radar apparatus as claimed in claim 7, characterised in that the selection means (98) comprise: a switching gate (102) for passing the clutter signal under the control of the clutter switching signal; and a comparator (100) for selecting the greater of the signal passed through the switching gate (102) and the temporary clutter level value supplied by the first memory means for writing into the third memory means (99).
Claim 10
Dependent Claim
79 words
Search radar apparatus as claimed in claim 7, characterised in that the selection means (98) comprise: a comparator (100) for generating a logical switching signal; an AND gate (101) fed with said switching signal and the clutter switching signal; and a switching gate (102) fed with the clutter signal and controlled by the AND gate (101), while the comparator (100) is supplied with the clutter signal and a temporary clutter level value ready available in the third memory means.
Claim 11
Dependent Claim
30 words
Search radar apparatus as claimed in claim 8 or 9, characterised in that the switching gate (102) comprises a second input for receiving the ready available temporary clutter level value.
Claim 12
Dependent Claim
79 words
Search radar apparatus as claimed in claim 8 or 9, characterised in that the selection means (98) comprise a three-position switching unit (105) for supplying a comparator signal designated as temporary clutter value to the selection means (98), whereby the switching unit (105) in a first position passes the zero value, in the second position the temporary clutter level value supplied by the first memory means (16), and in the third position the value supplied by selection means (98).
Claim 13
Dependent Claim
91 words
Search radar apparatus as claimed in claim 11, characterised in that the radar apparatus comprises a timing unit (104) for setting the three-position switching unit (105) to the first position (A) upon the supply of the clutter signal obtained as first in a clutter cell to selection means (98), to the second position (B) upon the supply of each subsequent clutter signal obtained in the clutter cell having the minimum range value, and to the third position (C) upon the supply of each other clutter signal obtained in the clutter cell.
Claim 14
Dependent Claim
96 words
Radar system provided with a first search radar apparatus as claimed in claim 6 for generating transmitter pulses of relatively short duration, and with a second search radar apparatus for generating transmitter pulses of a second type, characterised in that the radar system is designed for alternatively generating a transmitter pulse of the second type and a series of (N) transmitter pulses of relatively short duration, whereby the time interval between the instant of generating a transmitter pulse of the second type and that of the next transmitter pulse of short duration is a fixed value.
Claim 15
Dependent Claim
36 words
Radar system as claimed in claim 13, characterised in that the transversal filters are designed for producing a video signal only once during a period corresponding with the pulse repetition time of the second-type transmitter pulses.
Claim 16
Dependent Claim
59 words
Search radar apparatus as claimed in claim 1, characterised in that the video processing unit comprises a threshold circuit (106) for producing per clutter cell, upon the supply of a clutter video signal and a threshold value obtained from the standard clutter level, a clutter video value in the event said clutter video signal exceeds the standard clutter level.
Claim 17
Dependent Claim
40 words
Search radar apparatus as claimed in claim 15, characterised in that the video processing unit comprises a video selection circuit (107), connected to the canceller (2) and the threshold circuit (106), for selecting in magnitude the video signals supplied simultaneously.
References Cited (Backward Citations)
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