JPH03242581A - Processing device of radar signal - Google Patents

Abstract

PURPOSE:To prevent an increase in a false alarm by providing a threshold coefficient setting circuit and a switching constant false alarm rate circuit and by adding a distribution computing circuit, an average value computing circuit and an automatic function setting circuit of a constant false alarm rate. CONSTITUTION:Outputs of a pulse Doppler filter 1, an automatic function setting circuit 4 of a constant false alarm rate and a threshold coefficient setting circuit 5 are inputted to a switching constant false alarm rate circuit 8. In the switching constant false alarm rate circuit 8, either of a first constant false alarm rate circuit 6 or a second constant false alarm rate circuit 7 is selected on the basis of information from the circuit 4, and the output of the pulse Doppler filter 1 and a threshold level signal obtained by multiplying a threshold value comput ed on the basis of shift average values of a distance and a direction by a thresh old coefficient are compared with each other. A signal exceeding the threshold level signal is regarded as a target and an unnecessary signal and the number of separated targets are detected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention suppresses unnecessary signals in a radar device.
The present invention relates to a radar signal processing device that detects a target signal.

[Prior Art] In order to detect a target signal from radar reflected signals, it is necessary to suppress unnecessary signals in advance.

FIG. 2 shows an example of a conventional radar signal processing device that meets this requirement. In the figure, (1) is a pulse Doppler filter, and (9) is a fixed coefficient setting circuit.

(10) is a constant false alarm probability circuit. In addition, Fig. 4 (a
) and (b) are waveforms shown in a conventional radar signal processing device.

The pulse Doppler filter (1) is composed of a digital filter or a fast Fourier transform circuit. Fixed coefficient setting circuit (9) for setting the output of the pulse Doppler filter fl) and appropriate threshold coefficients
The output is input to a constant false alarm probability circuit (10). In the constant false alarm probability circuit (101), the output (15) of the pulse Doppler filter [1] and the threshold level signal 2 (23) obtained by multiplying the threshold value calculated based on the moving average value in the distance direction by the threshold coefficient are be compared. FIG. 4(a) shows a pulsed Doppler filter (1
) output (15) and threshold level signal 2 (
23) is shown. And threshold level signal 2
A signal exceeding (23) is regarded as a target, and a target number separated from unnecessary signals is detected.

[Problem to be solved by the invention] In the conventional signal processing device, a fixed coefficient setting circuit (9
), and the constant false alarm probability function method is determined, so if the distribution situation changes due to changes in the environment, there is a risk that the number of false alarms will increase.

A specific example will be explained using FIGS. 4(a) and 4(b). In FIG. 4(a), the first distribution (11),
Three types of distributions are set: a second distribution T12) and a third distribution (13). Here, the second distribution (12) sets an environment with many clutter edges. In this case, the range level of the output (15) of the pulse Doppler filter (1) changes depending on the difference in the distribution situation. However, since the threshold coefficient and the fixed rate alarm probability function are fixed, the threshold level signal 2 (23) is insufficient. Therefore, for the first distribution (11), , and the third distribution (13), the target [16].

Only target 4 (19), target 5 (20) can be captured, but in the second distribution (12), target 2 (17),
In addition to target 3 (18), unnecessary signal 1 (21) at the edge
, unnecessary signal 2 (22) is also captured. The result is
FIG. 4 (output as bl).Therefore, there was a problem of preventing this.

The present invention aims to solve this problem.

[Means for Solving the Problems] The radar signal processing device according to the present invention includes a threshold coefficient setting circuit (5) instead of the fixed coefficient setting circuit (9).
, a constant false alarm probability circuit (8) is provided instead of the constant false alarm probability circuit (lO), and a 9 distribution calculation circuit (2) is provided.
By adding an average value calculation circuit (3) and a constant false alarm probability function automatic setting circuit (4), it is possible to deal with any distribution characteristics of unnecessary signals, and to reduce the increase in false alarms. This is what I was trying to prevent.

[Function] In this invention, the threshold coefficient setting circuit (5) is switched instead of the fixed coefficient setting circuit (9), and the constant false alarm probability circuit (lO) is switched instead of the constant false alarm probability circuit (lO).
) and nine distribution calculation circuits (2).

An average value calculation circuit (3) and a constant false alarm probability function automatic setting circuit (4) are added. As a result, even if the properties of the two distributions change, it can be handled, and by setting the optimal threshold coefficient and constant false alarm probability function method for the properties of the distribution, an increase in false alarms can be further prevented.

[Embodiment] FIG. 1 shows an overall configuration diagram of an embodiment according to the present invention. In this figure, (1) is a pulsed Doppler filter,
(2) is a distribution calculation circuit, (3) is an average value calculation circuit, (4
) is a constant false alarm probability function automatic setting circuit, (5) is a threshold coefficient setting circuit, (6) is a first constant false alarm probability circuit, (7) is a second constant false alarm probability circuit, and (8) is a constant false alarm probability function automatic setting circuit. This is a switching constant false alarm probability circuit. Next, the operation of this device will be explained. FIGS. 3(a) and 3(b) show waveforms shown in the radar signal processing apparatus according to the present invention, that is, the output (15) of the pulse Doppler filter (1) and the threshold level signal 1 (14). At the output (15) of the pulse Doppler filter (1), (161 to (2
0) indicates a target, (211°(22) indicates an unnecessary signal.

The output (15) of the pulse Doppler filter (11) is input to the 9 distribution calculation circuit (2), the average value calculation circuit (3), and the switching constant false alarm probability circuit (8).Distribution calculation circuit (2)
Now let's understand the distribution of unnecessary signals. The average value calculation circuit (3) calculates a moving average value in the distance direction. The output of the distribution calculation circuit (2) and the output of the average value calculation circuit (3) are
It is input to the threshold coefficient setting circuit (5). The threshold coefficient setting circuit (5) calculates and sets an appropriate threshold coefficient. Also, 3 distribution calculation circuit (2
) output is a fixed amount? It is also input to the two-report probability function automatic setting circuit (4).

The fixed false alarm probability function automatic setting circuit (4) automatically sets which fixed false alarm probability function method to use for processing based on the obtained information. The output of the pulse Doppler filter (1) (15), the output of the constant false alarm probability function automatic setting circuit (4), and the output of the threshold coefficient setting circuit (5) are input to the switching constant false alarm probability circuit (8). . Switching constant false alarm probability circuit (8).

It consists of a first constant false alarm probability circuit (6) and a second constant false alarm probability circuit (7). Fixed false alarm probability function automatic setting circuit (4
), either the first constant false alarm probability circuit (6) or the second constant false alarm probability circuit (7) is selected, and the output (15) of the pulse Doppler filter m and the distance direction Threshold level signal 1 (
14) are compared. A signal exceeding the threshold level signal 1 (14) is regarded as a target, and a target number separated from unnecessary signals is detected. Here, in the second distribution (12), a constant false alarm probability function method that is strong against clutter edges and a larger threshold coefficient can be selected, so that only the target is detected.

[Effects of the Invention] As explained above, the present invention includes a fixed coefficient setting circuit (
Instead of 9), the threshold coefficient setting circuit (5) is used.
A switching constant false alarm probability circuit (8) is provided in place of the constant false alarm probability circuit (lO), and a 9 distribution calculation circuit (2), an average value calculation circuit (3), and a constant false alarm probability function automatic setting circuit (
By adding 4), it becomes possible to deal with any distribution characteristics of unnecessary signals, and it is possible to further prevent an increase in the false alarm probability in target detection.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a radar signal processing device according to the present invention, FIG. 2 is an overall configuration diagram of a conventional radar signal processing device, and FIGS. 3 (a) and (b) are radar signal processing devices according to the present invention. Figure 4 shows the waveform shown in fal,
fb) is a diagram showing a waveform shown by a conventional radar signal processing device. In the figure, (1) is a pulsed Doppler filter. (2) is a distribution calculation circuit, and (3) is an average value calculation circuit. (4) is a constant false alarm probability function automatic setting circuit, (5) is a threshold coefficient setting circuit, (6) is a first constant false alarm probability circuit, and (7) is a second constant false alarm probability circuit. (8) is a switching constant false alarm probability circuit, (9) is a fixed coefficient setting circuit, flO) is a constant false alarm probability circuit, (11)
is the first distribution, (12) is the second distribution, (13) is the third distribution, (14) is the threshold level signal 1
．． (15) is the output of the pulse Doppler filter (1),
(16) is goal 1, and (17) is goal 2. (18) is goal 3. (19) is goal 4, (201 is goal 5.
(21) is an unnecessary signal 1. (22) is an unnecessary signal 2. (23
) is the threshold level signal 2. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] A device that processes radar data consists of a digital filter or a fast Fourier transformer, which forms a filter bank, and uses a pulse Doppler filter for suppressing clutter and the output of the pulse Doppler filter as input to evaluate the distribution situation. a distribution calculation circuit for calculating the moving average value in the distance direction using the output of the pulse Doppler filter as input, and an average value calculation circuit for calculating the moving average value in the distance direction; A threshold coefficient setting circuit for calculating and setting an appropriate threshold coefficient, and an output of the distribution calculation circuit are input, and processing is performed using which constant false alarm probability function method according to the obtained information. a constant false alarm probability function automatic setting circuit for setting the constant false alarm probability function, and inputs the output of the pulse Doppler filter, the output of the constant false alarm probability function automatic setting circuit, and the output of the threshold coefficient setting circuit, and input data; a first constant false alarm probability circuit for comparing a moving average value in a distance direction with a threshold value based on a threshold coefficient and detecting a signal exceeding the threshold value as a target; and an output of the pulse Doppler filter. and the output of the constant false alarm probability function automatic setting circuit and the output of the threshold coefficient setting circuit as inputs,
A second fixed false alarm probability circuit that compares the input data with a moving average value in the distance direction and a threshold value based on the threshold coefficient brightness, and detects a signal exceeding the threshold brightness value as a target. A radar signal processing device that is clearly equipped with.