JPH03220483A - Radar signal processor - Google Patents

Abstract

PURPOSE:To measure an angle with an excellent accuracy when a clutter signal and a target signal are combined by controlling the on/off of LOG/CFAR processing on the basis of the presence or absence of the clutter signal and the intensity difference between the target signal and the clutter signal. CONSTITUTION:The radar signal of a radar apparatus is inputted from a antenna 101. After a clutter signal is suppressed by suppresser means 104, the radar signal is processed by LOG (Logarithm)/CFAR (Constant False Alarm Rate) processing means 105. One of the means 104 and 105 are selected 107 and an angle to be measured with respect to a radar target is calculated 108 on the basis of the selected means 104 or 105 and the position of the radar target. At the same time, the output of the means 105 is compared with a prescribed reference level and the detected position of the target is outputted from a target detector 106. Then, the output of the means 104 is shifted, the amplitude of a first range bin and the amplitude of the mean value of a prescribed number of second range bins in the neighboring time region of the first range bin are compared 109 with each other and a selector 107 is controlled 111 by a comparison result and the output of a clutter detector 110 for discriminating the region.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radar signal processing device, and more particularly to a signal processing device for a radar device that automatically measures the angle of a target.

[Conventional technology]

Conventionally, radar devices for measuring the angle of a target of this type have often adopted a monopulse method, and the angle of the target has been measured using the system shown in FIG.

That is, based on the sum pattern reception signal 202 and the difference pattern reception signal 203 received by the antenna 201, the position of the target is determined by the sum pattern reception signal, that is, the distance and direction in the case of a two-dimensional radar, and the direction and direction in the case of a three-dimensional radar. The distance, azimuth, and elevation angle are detected by the target detector 204, and the angle measurement calculator 205 calculates the difference in reception strength between the sum pattern reception signal and the difference pattern reception signal at the detected target position and the point at which the reception strength of the sum pattern is maximum. Angle measurements were performed based on the relationship between the deviation angle from

[Problem to be solved by the invention]

In the conventional radar device described above, the antenna reception signal includes, in addition to the target signal, reflected signals from fixed objects such as the ground and buildings (hereinafter referred to as fixed clutter).

This includes clutter signals that are unnecessary signals such as reflected signals from moving objects such as rain clouds (hereinafter referred to as moving clutter), but the radar signal processing device in the conventional monopulse angle measurement laser device described above does not suppress the clutter signal. Since it does not have a means, it has the disadvantage that angle measurement processing cannot be performed when a clutter signal is superimposed on the target signal.

Therefore, as a means of suppressing clutter signals, a radar signal processing device that performs target detection and angle measurement processing is used after using MTI processing and LOG/CFAR processing that makes the output video fluctuation constant regardless of the input video amplitude. It is considered. However, in the case of this type of radar signal processing device, average value calculation processing in LOG/CFAR processing (for LOG/CFAR processing, for example, 5KOLNIK, Introductino t
o Radar Systems, McGraw old 11
(For details, see the company), the received signal strength of each of the sum pattern and the difference pattern becomes a value different from the input received strength of the antenna, and it does not match the figure 8 characteristic, so there is a drawback that correct angle measurement cannot be performed.

[Means to solve the problem]

The radar signal processing device of the present invention includes a clutter suppressing means for inputting a radar signal in a radar device, suppressing and outputting a clutter signal caused by a fixed reflecting object, and receiving the output of the clutter suppressing means and converting it into L○G (logarithm) / CF. A
R(Con5tantFalse Aram Rate
) a LOG/CFAR processing means for suppressing and outputting a clutter signal caused by a moving reflecting object in the radar device; and a selection means for selectively outputting the output of either the LOG/CFAR processing means or the clutter suppression means. ,
An angle calculation means for performing angle measurement calculation for the radar target based on the output of the selection means and the position of the radar target, and the output of the LOG/CFAR processing means are compared with a predetermined reference level to detect the radar target. The target detection means outputs the detected position of the radar target to the angle measurement calculation means, and the amplitude value in the first range bin of interest while sequentially shifting the output of the clutter suppression means and the amplitude value in the vicinity of the first range bin. An amplitude comparing means for comparing the amplitude with the average amplitude value of a predetermined number of second range bins in the time domain, and outputting a selection control signal to the selecting means based on the result of the amplitude comparison by the amplitude comparing means. and selection control means.

Further, the radar signal processing device of the present invention includes a clutter detection means for determining a clutter area, and is configured to control the selection control means based on the output of the amplitude comparison means and the output of the clutter detection means. has.

Further, in the radar signal processing device of the present invention, the detection position of the radar target detected by the target detection means is within the clutter region detected by the clutter detection means, and the first If it is determined that the average amplitude value of the second range bin is larger than the amplitude value of the range bin by a predetermined value or more, the output of the LOG/CFAR processing means is selected as the output of the selection means, and If it is determined that the average amplitude value of the second range bin of the output signal of the clutter suppression means is smaller than the amplitude value of the first range bin by a predetermined value, the output of the clutter suppression means is selected. Further, the apparatus is configured to control the selection means so as to select the output of the clutter suppression means outside the clutter area.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a radar signal processing device of the present invention. The embodiment shown in FIG. 1 targets a radar signal acquired by a radar device that employs a monopulse method, and includes an antenna 101 that forms a sum pattern and a difference pattern, and a clutter suppressor 104 that suppresses and outputs clutter caused by fixed reflecting objects. and a LOG/CFAR processor 105 and processor stand 05FA that suppress and output clutter caused by moving reflective objects.
a target detector 106 that detects a radar target by comparing it with the judgment reference level of the processor stand 05 of the R processor 105; and a clutter suppressor 104 or LOG/CFIR processor 10.
a selector 107 that selectively outputs the output of process-105; and an angle-measuring calculator 1 that automatically measures the position of the radar target based on the output of the selector 107 and the output of the target detector 106.
08, an amplitude value in a first range bin as a time quantization unit at a constant time interval, which is focused on while sequentially shifting the output of the clutter suppressor 104, and a predetermined number in the vicinity of this first range bin. an amplitude comparator 109 that performs a moving comparison in the time domain with the average amplitude value in the second range bin of the antenna 101; and a selection controller 111 that outputs a selection control signal 112 to switch the selection of the selector 107 based on the output of the clutter detector 110 and the output of the target detector 106.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

Sum pattern received signal 102 output from antenna 101
and the difference pattern received signal 103 is transmitted to the clutter suppressor 10
4 performs clutter suppression.

The clutter suppressor 104 performs MTI processing for suppressing fixed clutter, and Doppler filter processing, so-called MD, for separating moving clutter that cannot be suppressed by MTI processing from the target signal based on the difference in Doppler frequency from the target signal. F 04ul-ti Doppler
Filter-er) processing is normally used. (For Doppler filter processing, for example, 5KOLNIK,
Introduction to Radar System
Familiar with stems and hlcGrawHil1. ) The clutter suppressor 104 performs MTI processing to remove stationary clutter as an unnecessary signal from a stationary reflecting object, while moving clutter is divided into a plurality of bands different for each Doppler frequency. LOG/CF radar signal
The AR processor 105 is caused to perform moving clutter removal on the processor table 05.

The output of the clutter suppressor 104 thus output is output as a fixed clutter suppression phase pattern reception signal 111 and a fixed clutter suppression difference pattern reception signal 112.

Now, if the Doppler frequencies of the target signal and the clutter signal sufficiently exceed each other, the clutter signal component superimposed on the target signal will be small. Therefore, the difference in intensity between the target signal and the clutter signal is such that the target signal is larger and sufficiently exceeds the predetermined reference level of the intensity comparator built into the clutter suppressor 104.

In this case, the LOG/CFAR processing unit 105 performs the LOG/CFAR function processing to erase the average level of clutter by logarithmizing the input video and subtracting the average value from the input video. The average value calculation also distorts the reception strength of the target signal, resulting in an angle measurement error in the angle measurement calculation performed by the angle measurement calculator 108 of the target detected by the target detector 106.

Therefore, when the target signal strength is sufficiently larger than the clutter signal strength, it is necessary to perform angle measurement calculation using the output signal of the clutter suppressor 104 as it is without suppressing the target signal by performing LOG/CFAR processing. That is, selector 107
The selector 107 is controlled by the selection controller 111 so that the output of the clutter suppressor 104 is sent out.

On the other hand, when the Doppler frequencies of the target signal and the clutter signal are close to each other, the number of components of the clutter signal superimposed on the target signal increases. For this reason, LOG
If the angle measurement calculation is performed without /CFAR processing, the angle measurement error will increase significantly due to the clutter signal component. Therefore,
In this case, the angle measurement error can be kept small by sufficiently suppressing the clutter signal component by performing LOG/CFAR processing.

Note that if there is no clutter, the difference in intensity between the target signal and the clutter signal will be greater for the target signal.
There is no need to perform LOG/CFAR processing.

The clutter detector 110 inputs the sum pattern signal 102, determines the clutter area by a known method, and supplies the result to the selection controller 111. Further, the amplitude comparator 109 sequentially moves the range bins (first range bin) with respect to the fixed clutter suppression sum pattern received signal output from the clutter suppressor 104, and a specific number of range bins (second range bins) before and after the range bin (first range bin).
Comparison of the amplitude value of the first range bin and the average amplitude value of the second range bin is performed one after another on radar signals obtained by radar scanning, and the results are selected. It is supplied to the controller 111.

The selection controller 111 obtains the outputs of the amplitude comparator 109 and the clutter detector 110 and selects the output of the clutter suppressor lO4 or L
The OG/CFAR processor 105 (processing amount 105) outputs a selection control signal 113 for selecting one of them and supplies it to the selector 107.

The above-mentioned selection control signal 113 outputs the output of the clutter suppressor 104 to the angle measurement calculator 10 when the target signal is sufficiently large compared to the clutter signal intensity and when no clutter exists.
8, and when the Doppler frequency of the target signal and clutter are close to each other, the control content is such that it is selectively output to the processing amount 105 calculator 108 of the LOG/CFAR processor 105.

In this way, the angle measurement calculator 108 can greatly suppress the influence of clutter and automatically calculate the angle measurement of the target position.

〔Effect of the invention〕

As described above, according to the present invention, LOG/CFAR processing is turned on based on the presence or absence of a clutter signal and the signal strength difference between the target signal and the clutter signal.

By controlling the OFF state, it is possible to realize a radar signal processing device that can obtain excellent angle measurement accuracy even when the target signal force f is superimposed on the clutter signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the radar signal processing apparatus of the present invention, and FIG. 2 is a block diagram of the radar signal processing apparatus. 101.201...Antenna, 102,202...Sum pattern received signal, 103,203...Difference pattern received signal, 104...Clutter suppressor, 105...L
OG/CFAR processor, 106, 204... Target detector, 107... Selector, 108, 205... Angle measurement calculator, 109... Amplitude comparator, 110... Clutter detector, 111...Selection controller, 111...Fixed clutter suppression sum pattern reception signal, 112...Fixed clutter suppression difference pattern reception signal, 113...Selection control signal.

Claims (3)

[Claims] (1) A clutter suppressing means for inputting a radar signal in a radar device, suppressing and outputting a clutter signal caused by a fixed reflecting object, and a LOG that receives the output of this clutter suppressing means.
(logarithm)/CFAR(ConstantFalseAr
amaRate) to suppress and output clutter signals caused by moving reflecting objects in radar equipment
FAR processing means; selection means for selectively outputting the output of either the LOG/CFAR processing means or the clutter suppression means; and angle measurement calculation for the radar target based on the output of the selection means and the position of the radar target. and a target detection means that outputs a detected position of the radar target to the angle measurement calculation means that compares the output of the LOG/CFAR processing means with a predetermined reference level and detects the radar target. , an amplitude for performing an amplitude comparison between the amplitude value in the first range bin of interest and the average amplitude value of a predetermined number of second range bins in the time domain near the first range bin while sequentially shifting the output of the clutter suppressing means; A radar signal processing device comprising a comparison means and a selection control means for outputting a selection control signal to the selection means based on the result of amplitude comparison by the amplitude comparison means. (2) Clutter detection means for determining a clutter area is provided, and the selection control means is controlled based on the output of the amplitude comparison means and the output of the clutter detection means. ) described radar signal processing device. (3) The detection position of the radar target detected by the target detection means is within the clutter area detected by the clutter detection means, and the amplitude value of the output signal of the amplitude comparison means is lower than the amplitude value of the first range bin. If it is determined that the average amplitude value of the second range bin is larger than a predetermined value, the LOG/
The output of the CFAR processing means is selected, and the average amplitude value of the second range bin of the output signal of the clutter suppression means is determined to be smaller than a predetermined value than the amplitude value of the first range bin. The radar signal processing according to claim 1, characterized in that the selecting means is controlled so as to select the output of the clutter suppressing means when the clutter region is outside the clutter region, and to select the output of the clutter suppressing means outside the clutter region. Device.