JPH05203726A - Radar signal processor - Google Patents

Abstract

(57) [Summary] [Object] To obtain a radar signal processing device for a radar device that suppresses unnecessary signals such as clutter and detects a target signal. In addition to a conventional radar signal processing device, a threshold coefficient automatic setting circuit 7 is provided instead of the fixed coefficient setting circuit 11, and a distribution calculation circuit 5, a sorting circuit 6, an optimum MAX value replacement circuit 8 and an optimum MIN. By adding the value replacement circuit 9, it is possible to prevent the moving average value in the distance direction near the target from becoming extremely large, and it is possible to set the optimum threshold level signal. [Effect] It is possible to prevent an increase in false alarms and obtain accurate detection information even under a proximity multi-target environment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a radar device,
The present invention relates to a radar signal processing device that suppresses unnecessary signals such as clutter and detects a target signal.

[0002]

2. Description of the Related Art In order to detect a target signal from reflected signals of a radar, it is necessary to suppress unnecessary signals such as clutter in advance. FIG. 2 is an example of a conventional radar signal processing device that meets this demand. 1 is a receiver, 2 is A / D
A conversion circuit, 3 is a pulse Doppler filter, 10 is a constant false alarm probability circuit, and 11 is a fixed coefficient setting circuit.

The radar signal processing device configured as described above operates as follows. The receiver 1 receives the reflected wave of the radar and converts it into a video signal. The output of the receiver 1 is input to the A / D conversion circuit 2. A / D conversion circuit 2
At, the video signal output from the receiver 1 is suppressed and converted into a digital video signal. The output of the A / D conversion circuit 2 is input to the pulse Doppler filter 3. The pulse Doppler filter 3 is composed of a digital filter or a fast Fourier transform circuit. The output of the pulse Doppler filter 3 is input to the video integration circuit 4. In the video integration circuit 4, a gain is given to a synchronous signal such as video and an asynchronous signal such as noise is suppressed, so that the signal-to-noise ratio is improved. The output of the video integration circuit 4 is input to the constant false alarm probability circuit 10. In the constant false alarm probability circuit 10, the video integration circuit 4
And the second threshold level signal obtained by multiplying the threshold value calculated based on the moving average value in the distance direction by the threshold coefficient set by the fixed coefficient setting circuit 11. Then, the signal exceeding the second threshold level signal is regarded as the target, and the target number separated from the clutter is detected.

[0004]

In the conventional radar signal processing apparatus, when the target amplitudes are different in a close proximity multi-target environment, a target having a small amplitude may be masked by a target having a large amplitude and may not be detected. There is. Figure 7
Will be described with reference to specific examples. FIG. 7 shows two adjacent
It is a waveform shown by a conventional radar signal processing device when a target detection process is performed. In the figure, 20 is the output of the video integration circuit 4, and 24 is the second threshold level signal. Further, in the output 20 of the video integration circuit 4, 21 is the first target and 22 is the second target. When there are two targets having different amplitudes, the moving average value in the distance direction in the vicinity of the target becomes extremely large, and accordingly, the second threshold level signal 24 becomes larger than the amplitude of the second target 22. As a result, the second target 22 becomes undetectable.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is a radar which can prevent the increase of false alarms and obtain accurate detection information even in a near multiple target environment. An object is to obtain a signal processing device.

[0006]

In the present invention, the threshold coefficient automatic setting circuit 7 is provided instead of the fixed coefficient setting circuit 11, and the distribution calculation circuit 5, the sorting circuit 6, and the optimum MAX.
A value replacement circuit 8 and an optimum MIN value replacement circuit 9 are added.
As a result, it is possible to prevent the threshold signal from becoming extremely large by removing the data having an extremely large amplitude in the proximity multi-target environment. As a result, it is possible to prevent an increase in false alarms and obtain accurate detection information.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the overall configuration of an embodiment according to the present invention. In this figure, 1 is a receiver, 2 is an A / D conversion circuit, 3 is a pulse Doppler filter, 4 is a video integration circuit, 5 is a distribution calculation circuit, 6 is a sorting circuit, 7 is a threshold coefficient automatic setting circuit, and 8 is An optimum MAX value replacement circuit, 9 is an optimum MAX value replacement circuit, and 10 is a constant false alarm probability circuit.

The radar signal processing device configured as described above operates as follows. The receiver 1 receives the reflected wave of the radar and converts it into a video signal. Output of receiver 1 is A
It is input to the / D conversion circuit 2. In the A / D conversion circuit 2, the video signal output from the receiver 1 is sampled and converted into a digital video signal. The output of the A / D conversion circuit 2 is input to the pulse Doppler filter 3. The pulse Doppler filter 3 is composed of a digital filter or a fast Fourier transform circuit. The output of the pulse Doppler filter 3 is input to the video integration circuit 4. In the video integration circuit 4, a gain is given to a synchronous signal such as video and an asynchronous signal such as noise is suppressed, so that the signal-to-noise ratio is improved. The output of the video integration circuit 4 is input to the distribution calculation circuit 5, the sorting circuit 6, and the constant false alarm probability circuit 10. The distribution calculation circuit 5 grasps the clutter distribution function. The output of the distribution calculation circuit 5 is input to the threshold coefficient automatic setting circuit 7, the optimum MAX value replacement circuit 8 and the optimum MIN value replacement circuit 9. In the sorting circuit 6,
Sort the inputs in descending order of amplitude. The output of the sorting circuit 6 is the optimum MAX value replacement circuit 8 and the optimum MIN.
It is input to the value replacement circuit 9. The threshold coefficient automatic setting circuit 7 automatically sets an optimum threshold according to the distribution function of clutter. The output of the threshold coefficient automatic setting circuit 7 is input to the constant false alarm probability circuit 10. In the optimum MAX value replacement circuit 8, the amplitude data rearranged by the sorting circuit is removed from the largest value to the Nth value, and the N + 1th value is converted to N.
Replace with the product of. The output of the optimum MAX value replacement circuit 8 is input to the constant false alarm probability circuit 10. Optimal MI
In the N-value substitution circuit 9, the amplitude data rearranged by the sorting circuit is replaced with a value obtained by removing the values from the smallest to the Mth and multiplying the M + 1th value by M. The output of the optimum MIN value replacement circuit 9 is input to the constant false alarm probability circuit 10. The constant false alarm probability circuit 10 compares the moving average value in the distance direction, the threshold coefficient, the threshold value based on the optimum MAX value and the optimum MIN value, and detects the signal exceeding the threshold level value as a target.

A more detailed description will be given with reference to FIGS. 3, 4 and 5. FIG. 3 shows a video integration circuit 4 in a reference cell in the radar signal processing device according to the present invention.
Shows the output waveform of. FIG. 4 shows an output waveform of the sorting circuit 6 in the reference cell in the radar signal processing device according to the present invention. FIG. 5 shows the optimum MAX in the reference cell in the radar signal processing device according to the present invention.
The output waveforms of the value substitution circuit 8 and the optimum MIN value substitution circuit 9 are shown. 3 and 4 and 5, 12 is the data with the largest amplitude, 13 is the data with the second largest amplitude, 14 is the data with the Nth largest amplitude, 15 is the data with the N + 1st largest amplitude, 16 Is data having the smallest amplitude, 17 is data having the second smallest amplitude, 18 is data having the smallest Mth amplitude, and 19 is data having the smallest M + 1th amplitude. First, the output waveform of the video integrator circuit 4 in the reference cell shown in FIG. 3 is rearranged by the sorting circuit 6 in descending order of amplitude as shown in FIG. Next, the optimum MAX value replacement circuit 8 removes the values from the largest to the Nth, and the N + 1th value becomes the Nth value.
At the same time, the optimum MIN value replacing circuit 9 removes the values from the smallest to the Mth, and replaces the M + 1th value by the M.
As a result, the waveform as shown in FIG. 5 is obtained.

[0010]

FIG. 6 is a waveform shown by the radar signal processing device according to the present invention when the two adjacent target detection processes are performed. In the figure, 20 is the output of the video integrator circuit 4, and 23 is the first threshold level signal.
Further, in the output 20 of the video integration circuit 4, 21 is the first target and 22 is the second target. The radar signal processing apparatus according to the present invention can prevent the moving average value in the distance direction in the vicinity of the target from becoming extremely large even when there are two targets having different amplitudes. A threshold level signal 23 of 1 can be set. As a result, it is possible to prevent an increase in false alarms and obtain accurate detection information even under a proximity multi-target environment. This is the fixed coefficient setting circuit 11
Threshold coefficient automatic setting circuit 7 is provided instead of
Further, the distribution calculation circuit 5, the sorting circuit 6, the optimum MA
This is an effect obtained by adding the X value replacement circuit 8 and the optimum MIN value replacement circuit 9.

[Brief description of drawings]

FIG. 1 is a diagram showing a radar signal processing device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional radar signal processing device.

FIG. 3 is an output waveform diagram of a video integration circuit 4 in a reference cell in the radar signal processing device according to the present invention.

FIG. 4 is an output waveform diagram of a sorting circuit 6 in a reference cell in the radar signal processing device according to the present invention.

FIG. 5 is an output waveform diagram of the optimum MAX value replacing circuit 8 and the optimum MIN value replacing circuit 9 in the reference cell in the radar signal processing device according to the present invention.

FIG. 6 is a waveform diagram shown in the radar signal processing device according to the present invention when the two adjacent target detection processes are performed.

FIG. 7 is a waveform diagram shown in the conventional radar signal processing device when the two adjacent target detection processes are performed.

[Explanation of symbols]

 1 Receiver 2 A / D conversion circuit 3 Pulse Doppler filter 4 Video integration circuit 5 Distribution calculation circuit 6 Sorting circuit 7 Threshold coefficient automatic setting circuit 8 Optimal MAX value replacement circuit 9 Optimal MIN value replacement circuit 10 Fixed false alarm probability circuit 11 Fixed Threshold coefficient setting circuit

Claims (1)

[Claims] 1. A circuit for processing data of a radar, wherein the receiver receives a reflected wave of the radar and converts it into a video signal, and the video signal output from the receiver is sampled and converted into a digital video signal. An A / D conversion circuit and a pulse Doppler filter for inputting the output of the AD conversion circuit and configured of a digital filter or a fast Fourier transformer to form a filter bank and suppress clutter, and the pulse Doppler filter A video integrator circuit for improving the signal-to-noise ratio of a received signal with the output as an input, a distribution calculating circuit for understanding the clutter distribution function with the output of the video integrator circuit as an input, and the video integrator circuit A sorting circuit for rearranging the input data by inputting the output of the With the output of the circuit as an input, a threshold coefficient automatic setting circuit for automatically setting the optimum threshold coefficient according to the distribution function of clutter,
Using the output of the distribution calculation circuit and the output of the sorting circuit as input, the amplitude data rearranged by the sorting circuit are replaced with those from the largest value to the Nth value and the N + 1th value multiplied by N. An optimum MAX value replacement circuit for performing the input, an output of the distribution calculation circuit and an output of the sorting circuit,
In the amplitude data rearranged by the sorting circuit, the values from the smallest to the Mth are removed, and M +
Optimal M to replace with the first value multiplied by M
An IN value replacement circuit, an output of the video integration circuit, an output of the threshold coefficient automatic setting circuit, an output of the optimum MAX value replacement circuit, and an output of the optimum MIN value replacement circuit are input, and a moving average value in the distance direction is input. And a constant false alarm probability circuit for comparing a threshold value based on a threshold coefficient, an optimum MAX value and an optimum MIN value, and regarding a signal exceeding the threshold level value as a target and detecting it. Radar signal processing device.