JPH0257993A - Radar target detecting apparatus - Google Patents

Abstract

PURPOSE:To restrain the decrease in a target detecting rate located between a beam and a beam by correcting the gain of a SIGMA video with an amplitude ratio between the SIGMA video and a DELTA video which are obtained with the patterns of the sum and the difference in a radar antenna, and thereafter performing video quantization. CONSTITUTION:A radar target detecting apparatus has a gain corrector 3, a video quantizer 1 and a correlator 2. A SIGMA video signal which is obtained with the sum pattern of a radar antenna and a DELTA video signal which is obtained with the difference pattern of the radar antenna are inputted into the corrector 3. The corrector 3 computes an amplitude ratio DELTA/SIGMA between the DELTA video and the SIGMA video with a divider. The result is outputted into a correcting coefficient generator. In a multiplier, the amplitude value of the SIGMA video is multiplied by the correcting coefficient which is outputted from the correcting coefficient generator so as to obtain a SIGMA' video signal. The signal is outputted into the quantizer 1. When the SIGMA' video signal exceeds a threshold value, the signal is detected as a hit signal in the quantizer 1. The correlation operation of a distance, an elevation angle and an azimuth angle is performed by using a synchronizing signal from the radar with respect to the hit signal in the correlator 2. Synthesis of the hit signals from the same target and the extraction of the distance, the altitude, the bearing and the like of the target are performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radar target detection device for detecting a target from a received video of a radar.

[Conventional technology]

Figure 4 shows the configuration of a conventional general radar target detection device. This is a correlator that uses synchronization signals to detect targets and extract information.

FIG. 5 shows the detailed configuration of the video quantizer 1, in which 11 is a comparator and 12 is a dark value generating circuit.

Next, the operation will be explained.

A video signal from a radar device is compared with a dark value by a comparator 11, and a signal exceeding a threshold value is detected as a hit signal. This dark value is created by the threshold value generation circuit 12, and there are various methods, but a common method is to multiply the average level of a certain section of the video signal by a predetermined coefficient.

Next, the correlator 2 performs correlation processing on the distance, elevation angle, and azimuth angle of the human signal using the synchronization signal from the radar, thereby integrating the human signals from the same target and determining the distance of the target.
Extract altitude, direction, etc. The target information detected by the correlator 2 is further input to a calculator or the like, and is used for target tracking calculations and display processing as necessary.

[Problem to be solved by the invention]

Conventional radar target detection devices are configured as described above, and although there is no problem with radars that scan with a wide beam such as a fan beam, there is a problem with radars that scan space discretely with a narrow pencil beam. In this case, the video of the target captured at the center of the beam and the video of the target captured away from the center of the beam are detected with the same darkness value, and the detection rate of targets located between the beams is particularly low. This problem arises. For this reason, it was necessary to either sacrifice spatial scanning speed or increase the beam width and sacrifice measurement accuracy.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a radar target detection device that can reduce the decrease in detection rate of targets located between beams.

[Means to solve the problem]

The radar target detection device according to the present invention converts the gain of a video signal (hereinafter referred to as Σ video) obtained by a sum pattern of radar antennas into the gain of a video signal obtained by a difference pattern between the amplitude of the Σ video and a radar antenna. A gain correction circuit that corrects based on the ratio of the amplitude of the signal (hereinafter referred to as Δ video),
This is added before the video quantization circuit.

[Effect]

In this invention, the gain correction circuit calculates the deviation angle from the target beam center from the amplitude ratio of Δ video and Σ video,
The gain of the Σ video is increased in accordance with the deviation angle to compensate for the attenuation of the Σ video due to deviation from the beam center.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a radar target detection apparatus according to an embodiment of the present invention, in which 3 is a gain corrector, 1 is a video quantizer, and 2 is a correlator.

FIG. 2 shows a more detailed configuration of the gain corrector 3, in which 31 is a divider, 32 is a correction coefficient generator, and 33 is a multiplier.

Next, the operation will be explained.

Here, the video signal obtained from the sum pattern of the radar antenna (Σ video) and the video signal obtained from the difference pattern of the radar antenna (Δ video) are the monopulse angle measurement method used to improve the angle measurement accuracy of the target. There is a relationship shown in Figure 6, and the deviation angle 1Δ from the beam center is
θ1 can be found. Therefore, the deviation angle 1Δθ
In order to compensate for the attenuation of the Σ video due to deviation from the beam center by increasing the gain of the Σ video according to the The gain corrector 3 corrects the Σ video.

That is, in the gain corrector 3, the divider 31 calculates the amplitude ratio Δ/Σ of Δ video and Σ video, and outputs the result to the correction coefficient generator 32. The correction coefficient generator 32 is, for example, a ROM.
(Read Only Memory)
According to the calculation result of the divider 31, a correction coefficient corresponding to the gain correction amount shown by the broken line in FIG. 7 is generated. Multiplier 33
multiplies the amplitude value of the Σ video by this correction coefficient and outputs it to the video quantizer 1 as a Σ' video.

The video quantizer 1 performs exactly the same operation as described in the conventional example, and compares the Σ'' video signal with the dark value, and detects the signal exceeding the dark value as a human signal. Correlation processing of distance, elevation angle, and azimuth angle is performed on the signal using a synchronization signal from the radar to integrate human signals from the same target and extract target distance, altitude, azimuth, etc. Detected by correlator 2 The target information is further input to a calculator or the like and used for target tracking calculations and display processing as necessary.

In addition, in the above embodiment, the gain correction of Σ video is always performed, but the gain correction may be performed only when there is a significant signal of a certain level or higher in the Δ video.
In this case, gain correction can be performed only when gain correction is truly necessary, and it is possible to prevent unnecessary correction from being performed on Σ video when Δ video fluctuates due to noise.

The configuration of the gain correction circuit according to another embodiment of the present invention is shown in FIG. 33, and otherwise outputs the input Σ video as is.

〔Effect of the invention〕

As described above, according to the present invention, video quantization is performed after correcting the gain of Σ video using the amplitude ratio of Δ video and Σ video. This has the effect of suppressing a decrease in the detection rate of targets located in the valley of the beam.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a radar target and detection device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a gain correction circuit according to the present invention, and FIG. 3 is a block diagram showing a gain correction circuit according to another embodiment of the present invention. FIG. 4 is a block diagram showing a conventional radar target detection device, FIG. 5 is a block diagram showing a video quantizer according to the conventional example and an embodiment of the present invention, and FIG. 6 is a block diagram showing the circuit. Δ
An explanatory diagram showing the principle of calculating the deviation angle 1Δθ1 from the beam center from the amplitude ratio Δ/Σ of video and Σ video. FIG. 7 is an explanatory diagram showing the relationship between the deviation angle from the beam center and the gain correction amount. 1 is a video quantizer, 11 is a comparator, 12 is a dark value generation circuit, 2 is a correlator, 3 is a gain corrector (gain correction means), 3
32 is a correction coefficient generator, and 33 is a multiplier. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In a radar target detection device, an amplitude ratio calculating means for calculating the amplitude ratio of a video signal obtained by a sum pattern of the radar antenna and a video signal obtained by a difference pattern; A radar target detection device comprising: gain correction means for correcting the gain of the obtained video signal.