EP0227457A2
Expired / Lapsed
EP
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Radar system
Assignee: NEC Corp
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Filing: 1986-12-22
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Granted: —
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Expires: 2006-12-22
Abstract
Abstract A radar system includes N Doppler filters (30₁ to 30 N ) (N is an integer larger than 1), N CFAR (Constant False Alarm Rate) processing means (31₁ to 31 N ), a video selector (33), automatic target detecting means (34), a video integrator (35), and a D/A converter (36). The N CFAR processing means (31₁ to 31 N ) are respectively connected to output terminals of the Doppler filters and automatically adapt amplitude distribution characteristics of a signal, such as clutter and receiver noise, and convert the signal into a signal having the same amplitude distribution characteristics as the receiver noise and suppressing the converted signal. The video selector (33) is connected to output terminals of the N CFAR processing means and selects an output signal from any one thereof in units of radar range bins and synthesizes an N channel signals into a single channel signal. The automatic target detecting means (34) is connected to an output terminal of the video selector (33). The video integrator (35) is connected to an output terminal of the video selector (33) and generates a signal at each transmission pulse by interpolating a single Doppler filter output signal for each M (≧ N) transmission pulses. The D/A converter (36) is connected to the video integrator (35) and generates an analog video signal.
Inventors
- 👤 Eiichi Kuichi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 17:34
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/52; G01S13/522; G01S13/524; G01S13/5246
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
170 words
A radar system characterized by comprising: N Doppler filters (30₁ to 30 N ) (N is an integer larger than 1) each of which has a configuration of digital filter with M stages (M is an integer); N CFAR (Constant False Alarm Rate) processing means (31₁ to 31 N ), respectively connected to output terminals of said Doppler filters for suppressing spaciously spreading clutter signals; a video selector (33), connected to output terminals of said N CFAR processing means, for selecting an output signal from any one thereof in units of radar range bins and synthesizing N channel signals into a single channel signal; automatic target detecting means (34) connected to an output terminal of said video selector (33); a video integrator (35), connected to an output terminal of said video selector (33), for reproducing a signal at each transmission pulse by interpolating Doppler filter output signal for each M transmission pulse hits; and a D/A converter (36), connected to said video integrator (35), for generating an analog video signal.
Claim 2
Dependent Claim
170 words
A radar system characterized by comprising: N Doppler filters (30₁ to 30 N ) (N is an integer larger than 1) each of which has a configuration of digital filter with M stages (M is an integer); N CFAR (Constant False Alarm Rate) processing means (31₁ to 31 N ), respectively connected to output terminals of said Doppler filters for suppressing spaciously spreading clutter signals; a video selector (33), connected to output terminals of said N CFAR processing means, for selecting an output signal from any one thereof in units of radar range bins and synthesizing N channel signals into a single channel signal; automatic target detecting means (34) connected to an output terminal of said video selector (33); a video integrator (35), connected to an output terminal of said video selector (33), for reproducing a signal at each transmission pulse by interpolating Doppler filter output signal for each M transmission pulse hits; and a D/A converter (36), connected to said video integrator (35), for generating an analog video signal.
Claim 3
Dependent Claim
37 words
A radar system according to claim 1, wherein said CFAR processing means (31₁ to 31 N ) are Weibull CFAR processing means capable of subjecting a signal having Weibull distribution characteristics as amplitude characteristics to CFAR processing.
Claim 4
Dependent Claim
97 words
A radar system according to claim 1, wherein said CFAR processing means (31₁ to 31 N ) comprise LOG/CFAR processing means capable of subjecting a signal having Rayleigh distribution characteristics as amplitude characteristics to CFAR processing, and automatic gain adjusting means (31₁ to 32 N ), connected to an output terminal of said LOG/CFAR processing means, for adapting to a remaining signal obtained by subjecting a signal having amplitude characteristics of a non-Rayleigh distribution to LOG/CFAR processing, and for converting the remaining signal into a signal having equivalent amplitude level to that of the receiver noise signal.
Claim 5
Dependent Claim
61 words
A radar system according to claim 3, wherein said automatic gain adjusting means (32₁ to 32 N ) comprises means for detecting a maximum value of an amplitude of the remaining signal within a predetermined range after LOG/CFAR processing, and automatic gain control means which performs automatic gain adjustment in order to give an attenuation proportional to the detected maximum amplitude.
Claim 6
Dependent Claim
117 words
A radar system according to claim 1, wherein said radar system further comprises: amplitude interpolating means (12) for providing analog video, when a signal level of an azimuth of interest, among signals of output signals from said video selector (33) that are continuous in adjacent azimuths in a predetermined range, is smaller than a value uniquely determined as a function of adjacent signal levels, the value uniquely determined as the function of the adjacent signal levels as a value representing an output of the azimuth of interest in the predetermined range; and integrating means (13) for performing smoothing integration of the output from said amplitude interpolating means (33) with respect to predetermined azimuths in a predetermined range.
Claim 7
Dependent Claim
97 words
A radar system according to claim 5, wherein said amplitude interpolating means (12; 12ʹ) further has: first and second memories (41, 42), connected in series with each other, for sequentially storing and outputting an input signal at an input timing of the input signal; an arithmetic operational circuit (43, 44) for calculating half of a sum of the input signal and an output from said second memory (42); and comparing/selecting means (47, 48) for comparing an output from said arithmetic operational circuit (43, 44) with an output from said first memory (41) and outputting a larger output.
Claim 8
Dependent Claim
54 words
A radar system according to claim 6, wherein said amplitude interpolating means (12; 12ʹ; 12ʺ) further comprises a comparator (55) for comparing the output from said arithmetic operational circuit (43, 44) and a preset threshold value and, when the output is larger than the threshold value, activating said comparing/selecting means (47, 48; 56, 58).
Claim 9
Dependent Claim
75 words
A radar system according to claim 5, wherein said smoothing integrating means (13; 13ʹ) has memories (61, 64, 66), connected in series with each other to constitute a delay circuit, for adding to an output from each of said memories (61, 64, 66) a product obtained by multiplying an output from a memory (66) of the last stage by a predetermined multiplicand, and for inputting the obtained sum to a memory of a next stage.
References Cited (Backward Citations)
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