Clutter Identification Device and Clutter Identification Program

Abstract

To automatically execute processing and also eliminate the need for complicated processing in a radar technology for identifying a target as a clutter.SOLUTION: A clutter identification device 2 comprises: a reflection intensity extraction part 22 which extracts information on a reflection intensity and a reflection distance from a radar signal; and a clutter identification part 23 which identifies the radar signal as a signal due to a clutter when the reflection intensity is smaller than an intensity threshold and the reflection distance is smaller than a distance threshold (1), and identifies the radar signal as a signal due to a target when the reflection intensity is not smaller than the intensity threshold and the reflection distance is not smaller than the distance threshold neither (2).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to radar technology for identifying a target as clutter.

Background Art

[0002] Radar technology for identifying a target as clutter is disclosed in Patent Document 1. Examples of clutter include sea clutter and ground clutter. In Patent Document 1, STC (Sensitive Time Control) is used to reduce the reflection intensity at closer distances and maintain the reflection intensity at farther distances, thereby identifying the target as clutter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In general technology, the user adjusts the degree of reduction of the reflection intensity of STC and then identifies the target as clutter. In Patent Document 1, the degree of reduction of the reflection intensity of STC is automatically adjusted and then the target is identified as clutter. However, in the case of a drone or the like, unlike general technology, the user cannot adjust the degree of reduction of the reflection intensity of STC, and unlike Patent Document 1, it is not possible to execute a complicated process of automatically adjusting the degree of reduction of the reflection intensity of STC.

[0005] Therefore, in order to solve the above problems, an object of the present disclosure is to automatically execute a process and eliminate a complicated process in radar technology for identifying a target as clutter.

Means for Solving the Problems

[0006] In order to solve the above problems, the present disclosure applies the fact that the reflection intensity and reflection distance due to clutter are distributed only at small reflection intensities and reflection distances compared to the reflection intensity and reflection distance due to a target, for the discrimination between clutter and a target.

[0007] Specifically, the present disclosure provides a clutter discrimination device comprising: a reflection intensity extraction unit that extracts information on reflection intensity and reflection distance from a radar signal; and a clutter discrimination unit that discriminates that the radar signal is due to clutter if (1) the reflection intensity is less than an intensity threshold and the reflection distance is less than a distance threshold, and discriminates that the radar signal is due to a target if (2) the reflection intensity is less than the intensity threshold and the reflection distance is less than the distance threshold does not apply.

[0008] Further, the present disclosure provides a clutter discrimination program for causing a computer to sequentially execute: a reflection intensity extraction step of extracting information on reflection intensity and reflection distance from a radar signal; and a clutter discrimination step of discriminating that the radar signal is due to clutter if (1) the reflection intensity is less than an intensity threshold and the reflection distance is less than a distance threshold, and discriminating that the radar signal is due to a target if (2) the reflection intensity is less than the intensity threshold and the reflection distance is less than the distance threshold does not apply.

[0009] According to these configurations, in radar technology for discriminating a target from clutter, processing can be automatically executed and the discrimination accuracy can be further improved.

[0010] In order to solve the above problems, the present disclosure applies the fact that the velocity dispersion due to clutter is distributed up to a large velocity dispersion compared to the velocity dispersion due to a target, for the discrimination between clutter and a target.

[0011] Specifically, the present disclosure provides a clutter identification device further comprising a velocity dispersion extraction unit that extracts velocity dispersion information from the radar signal, and the clutter identification unit (1) identifies the radar signal as being caused by clutter if the velocity dispersion is greater than a dispersion threshold, and (2) identifies the radar signal as being caused by either clutter or a target if the velocity dispersion is not greater than the dispersion threshold.

[0012] This arrangement allows radar techniques for distinguishing targets from clutter to be performed automatically and with greater accuracy.

[0013] The present disclosure also provides a clutter identification device, characterized in that the clutter identification unit (1) stops outputting the radar signal to a radar display device when it identifies that the radar signal is due to clutter, and (2) starts outputting the radar signal to the radar display device when it identifies that the radar signal is due to a target.

[0014] This arrangement allows radar technology to automatically remove clutter without requiring complex processing to distinguish targets from clutter. Effect of the Invention

[0015] In this manner, the present disclosure provides an automated and non-complex process for radar technology that distinguishes targets from clutter. [Brief description of the drawings]

[0016]

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DETAILED DESCRIPTION OF THE INVENTION

[0017] Embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of the implementation of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0018] The configuration of the radar system of the present disclosure is shown in FIG. 1. The radar system R includes a radar transceiver 1, a clutter identification device 2, and a radar display device 3. The clutter identification device 2 includes a speed dispersion extraction unit 21, a reflection intensity extraction unit 22, and a clutter identification unit 23. The clutter identification device 2 can be realized by installing the clutter identification program shown in FIG. 4 or FIG. 5 in a computer (for example, a CPU, etc.), and can be realized by causing an IC (for example, an FPGA, etc.) having a ROM to execute the clutter identification process shown in FIG. 4 or FIG. 5, and can also be realized by including both the above computer and the IC having a ROM. Examples of clutter include sea clutter and ground clutter. In the following description, sea clutter is assumed as the clutter.

[0019] The first clutter identification principle of the present disclosure is shown in FIG. 2. The speed dispersion caused by clutter is distributed from a speed dispersion of almost 0 to a large speed dispersion. The speed dispersion caused by a target is distributed from a speed dispersion of almost 0 to a small speed dispersion. That is, the speed dispersion caused by clutter is distributed to a large speed dispersion compared to the speed dispersion caused by a target. Note that the target speed caused by clutter has almost the same target speed distribution as the target speed caused by a target.

[0020] Therefore, the clutter identification unit 23 identifies whether the radar signal is due to clutter or a target based on the information on the velocity dispersion. Specifically, if the velocity dispersion is greater than the dispersion threshold, the clutter identification unit 23 identifies that the radar signal is due to clutter. On the other hand, if the velocity dispersion is not greater than the dispersion threshold, the clutter identification unit 23 identifies that the radar signal is due to either clutter or a target. Here, examples of the dispersion threshold include the vicinity of the upper limit of the distribution of the velocity dispersion due to a target. Then, the dispersion threshold may be set smaller (larger) according to good weather (bad weather).

[0021] The second clutter identification principle of the present disclosure is shown in FIG. 3. The reflection intensity and reflection distance due to clutter are distributed from substantially zero reflection intensity and reflection distance to small reflection intensity and reflection distance. The reflection intensity due to a target is distributed to a large reflection intensity if the reflection distance is short, and is distributed from substantially zero reflection intensity to small reflection intensity if the reflection distance is long. That is, the reflection intensity and reflection distance due to clutter are distributed only to small reflection intensity and reflection distance as compared with the reflection intensity and reflection distance due to a target. Note that the reflection intensity due to clutter has a lower dependency on the reflection distance according to the operation of STC as compared with the reflection intensity due to a target.

[0022] Therefore, the clutter identification unit 23 identifies whether the radar signal is due to clutter or a target based on the information on the reflection intensity and reflection distance. Specifically, if the reflection intensity is less than the intensity threshold and the reflection distance is less than the distance threshold, the clutter identification unit 23 identifies that the radar signal is due to clutter. On the other hand, if the reflection intensity is not less than the intensity threshold or the reflection distance is not less than the distance threshold, the clutter identification unit 23 identifies that the radar signal is due to a target. Here, examples of the intensity threshold and the distance threshold include the vicinity of the upper limit of the distribution of the reflection intensity and reflection distance due to clutter. Then, the intensity threshold and the distance threshold may be set smaller (larger) according to good weather (bad weather).

[0023] Thus, in the radar technology for identifying a target as clutter, processing can be automatically executed and complex processing can be made unnecessary. Of course, STC may be used, but it is not necessary to have many types of STC curves. Then, it is possible to apply that the speed dispersion due to clutter is distributed to a large speed dispersion. Further, it is possible to apply that the reflection intensity and the reflection distance due to clutter are distributed only to a small reflection intensity and a small reflection distance.

[0024] Here, the clutter identification unit 23 can also identify whether the radar signal is due to clutter or a target based on the information of speed dispersion, reflection intensity, and reflection distance. Therefore, in the radar technology for identifying a target as clutter, processing can be automatically executed and the identification accuracy can be made higher. In the following description, two types of procedures are shown.

[0025] The first clutter identification procedure of the present disclosure is shown in FIG. 4. In the first procedure, identification based on speed dispersion is prioritized, and the priority identification result can be narrowed down by identification based on reflection intensity and reflection distance.

[0026] The speed dispersion extraction unit 21 extracts information on speed dispersion from the radar signals of each range and each sector (step S1). The reflection intensity extraction unit 22 extracts information on reflection intensity and reflection distance from the radar signals of each range and each sector (step S1).

[0027] If the speed dispersion is greater than the dispersion threshold (step S2, YES), the clutter identification unit 23 identifies that the radar signal is due to clutter (step S3) and stops the output of the radar signal to the radar display device 3 (step S4).

[0028] If the speed dispersion is not greater than the dispersion threshold (step S2, NO) and if the reflection intensity is less than the intensity threshold and the reflection distance is less than the distance threshold (step S5, YES), the clutter identification unit 23 identifies that the radar signal is due to clutter (step S6) and stops the output of the radar signal to the radar display device 3 (step S7).

[0029] When the clutter identification unit 23 does not apply when the speed dispersion is greater than the dispersion threshold (step S2, NO), and does not apply when the reflection intensity is less than the intensity threshold and the reflection distance is less than the distance threshold (step S5, NO), the radar signal is identified as being due to a target (step S8), and the radar signal is output to the radar display device 3 (step S9).

[0030] In this way, in the radar technology for identifying a target as clutter, it is possible to automatically perform clutter removal and eliminate the need for complex processing.

[0031] The second clutter identification procedure of the present disclosure is shown in FIG. 5. In the second procedure, equivalent handling of identification based on speed dispersion and identification based on reflection intensity and reflection distance is possible.

[0032] The speed dispersion extraction unit 21 extracts information on speed dispersion from the radar signals of each range and each sector (step S11). The reflection intensity extraction unit 22 extracts information on reflection intensity and reflection distance from the radar signals of each range and each sector (step S11).

[0033] When the clutter identification unit 23 applies when the speed dispersion is greater than the dispersion threshold (step S12, YES), and applies when the reflection intensity is less than the intensity threshold and the reflection distance is less than the distance threshold (step S13, YES), the radar signal is identified as being due to clutter (step S14), and the output of the radar signal to the radar display device 3 is aborted (step S15).

[0034] When the clutter identification unit 23 applies when the speed dispersion is greater than the dispersion threshold (step S12, YES), and does not apply when the reflection intensity is less than the intensity threshold and the reflection distance is less than the distance threshold (step S13, NO), the radar signal is identified as being due to either clutter or a target (step S16). Note that the clutter identification unit 23 may execute or abort the output of the radar signal to the radar display device 3 for conflicting identification results.

[0035] When the clutter identification unit 23 does not apply when the speed dispersion is greater than the dispersion threshold (step 12, NO), and applies when the reflection intensity is less than the intensity threshold and the reflection distance is less than the distance threshold (step S17, YES), it identifies that the radar signal is due to clutter (step S18), and aborts the output of the radar signal to the radar display device 3 (step S19).

[0036] When the clutter identification unit 23 does not apply when the speed dispersion is greater than the dispersion threshold (step S12, NO), and does not apply when the reflection intensity is less than the intensity threshold and the reflection distance is less than the distance threshold (step S17, NO), it identifies that the radar signal is due to a target (step S20), and executes the output of the radar signal to the radar display device 3 (step S21).

[0037] Thus, in the radar technology for identifying a target from clutter, it is possible to automatically perform clutter removal and eliminate the need for complex processing.

[0038] Experimental results of the target speed and speed dispersion of the present disclosure are shown in FIG. 6. Experimental results of the reflection intensity and reflection distance of the present disclosure are shown in FIG. 7. Here, STC is used and there is only one type of STC curve. And MTI (Moving Target Indicator) is used, and since the drone equipped with the radar system R is moving at about 10 m / s, a target speed of about 10 m / s is not detected. Further, as targets, a nearby helicopter and a distant fishing boat are detected, and as clutter, sea clutter is considered.

[0039] In FIG. 6, clutter and targets are identified by visual recognition by the user, and about 20 m 2 / s 2The velocity dispersion is due to clutter and not due to the target. In Fig. 7, the reflection intensity in the range of about 40 to 60 is the same for both clutter and the target. Therefore, the clutter identification program shown in Fig. 4 may be executed, giving priority to identification based on velocity dispersion and narrowing down the priority identification results with identification based on reflection intensity and reflection distance.

[0040] In this embodiment, dispersion thresholds, intensity thresholds, and distance thresholds are empirically set for velocity dispersion, reflection intensity, and reflection distance. As a modification, a dataset associating clutter or a target with velocity dispersion, reflection intensity, and reflection distance may be machine-learned.

Industrial Applicability

[0041] Thus, the clutter identification device and clutter identification program of the present disclosure can automatically execute processing and eliminate complicated processing regardless of whether they are applied to drones or manned aircraft, etc. in radar technology for identifying a target as clutter.

Explanation of Signs

[0042] R: Radar system 1: Radar transceiver 2: Clutter identification device 3: Radar display device 21: Velocity dispersion extraction unit 22: Reflection intensity extraction unit 23: Clutter identification unit

Claims

1. A reflected intensity extraction unit that extracts information on reflected intensity and reflection distance from a radar signal, a velocity dispersion extraction unit that extracts information on velocity dispersion from the radar signal, a clutter discrimination unit that discriminates whether the radar signal is due to clutter or a target based on the information on the reflected intensity, the reflection distance, and the velocity dispersion, comprising: The clutter discrimination unit discriminates that the radar signal is due to clutter if (1) the velocity dispersion is greater than a dispersion threshold value; discriminates that the radar signal is due to clutter if (2) the velocity dispersion is not greater than the dispersion threshold value, the reflected intensity is less than an intensity threshold value having no dependence on the reflection distance, and the reflection distance is less than a distance threshold value; and discriminates that the radar signal is due to a target if (3) the velocity dispersion is not greater than the dispersion threshold value, the reflected intensity is less than the intensity threshold value having no dependence on the reflection distance, and the reflection distance is not less than the distance threshold value. A clutter discrimination device characterized by the above.

2. A reflected intensity extraction unit that extracts information on reflected intensity and reflection distance from a radar signal, a velocity dispersion extraction unit that extracts information on velocity dispersion from the radar signal, a clutter discrimination unit that discriminates whether the radar signal is due to clutter or a target based on the information on the reflected intensity, the reflection distance, and the velocity dispersion, comprising: The clutter discrimination unit discriminates that the radar signal is due to clutter if (1) the velocity dispersion is greater than a dispersion threshold value, the reflected intensity is less than an intensity threshold value having no dependence on the reflection distance, and the reflection distance is less than a distance threshold value; discriminates that the radar signal is due to clutter if (2) the velocity dispersion is not greater than the dispersion threshold value, the reflected intensity is less than the intensity threshold value having no dependence on the reflection distance, and the reflection distance is less than the distance threshold value; and discriminates that the radar signal is due to a target if (3) the velocity dispersion is not greater than the dispersion threshold value, the reflected intensity is less than the intensity threshold value having no dependence on the reflection distance, and the reflection distance is not less than the distance threshold value. A clutter discrimination device characterized by the above.

3. When the clutter identification unit identifies that the radar signal is due to clutter, the output of the radar signal to the radar display device is stopped, and (2) when the radar signal is identified as being due to a target, the output of the radar signal to the radar display device is executed. The clutter identification device according to claim 1 or 2, characterized in that.

4. A reflected intensity extraction step of extracting information on the reflection intensity and reflection distance from the radar signal, A speed dispersion extraction step of extracting information on the speed dispersion from the radar signal, A clutter identification step of identifying whether the radar signal is due to clutter or a target based on the information on the reflection intensity, the reflection distance, and the speed dispersion, Let the computer execute them in order, In the clutter identification step, (1) if the speed dispersion is greater than the dispersion threshold, the radar signal is identified as being due to clutter, (2) if the speed dispersion is not greater than the dispersion threshold, the reflection intensity is less than the intensity threshold having no dependence on the reflection distance, and the reflection distance is less than the distance threshold, the radar signal is identified as being due to clutter, and (3) if the speed dispersion is not greater than the dispersion threshold, the reflection intensity is less than the intensity threshold having no dependence on the reflection distance, and the reflection distance is not less than the distance threshold, the radar signal is identified as being due to a target. A clutter identification program characterized by that.

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