Radar signal processing device, radar signal processing program, and radar image display device

Abstract

To improve a display mode of a radar image so as to execute suppression processing of a clutter, such as sea surface reflection and rain-and-snow reflection at a moderate suppression level.SOLUTION: A radar signal processing device S includes: a first radar image output section 1 for outputting a first radar image by executing suppression processing of a clutter to a radar signal; a second radar image output section 2 for disabling execution of suppression processing of a clutter to a radar signal or executing suppression processing of a clutter to it much weaker than to the first radar image and outputting a second radar image; and a radar image display section 3 for performing a transmission display and a lower display of the second radar image and performing an upper display of the first radar image when superposingly displaying the first radar image and the second radar image on a radar image display device D.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to radar technology that suppresses clutter such as sea clutter or rain and snow clutter. [Background technology]

[0002] Patent Document 1 discloses a radar technology that detects targets such as ships or buoys by synthesizing a nautical chart and radar images. Radar technology that detects targets such as ships or buoys by connecting and synthesizing multiple types of radar images exists as a conventional technology. In the conventional technology, targets such as ships or buoys are detected by connecting and synthesizing radar images from a long distance from the ship and radar images from a short distance from the ship, or by connecting and synthesizing radar images in front of the ship and radar images behind the ship. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-279641 A Summary of the Invention [Problem to be solved by the invention]

[0004] Radar technology that detects targets such as ships or buoys by suppressing clutter such as sea surface clutter or rain / snow clutter is known as a conventional technology, but has the following problems.

[0005] The first radar signal processing problem of the conventional technology is shown in Figure 1. In the left column of Figure 1, suppression processing of clutter such as sea clutter or rain / snow clutter is executed for the radar signal at a high suppression level. As a result, clutter such as sea clutter or rain / snow clutter is excessively suppressed in close range from the ship, etc., and targets with weak reflection strength such as small ships or buoys may also be excessively suppressed.

[0006] In the right column of Figure 1, suppression processing of clutter such as sea clutter or rain / snow clutter is performed on the radar signal at a low suppression level. As a result, clutter such as sea clutter or rain / snow clutter is displayed to a certain extent in the vicinity of the ship, etc., but targets such as small vessels or buoys with weak reflection strength are also displayed to the same extent, and it is possible that clutter and targets are not properly distinguished.

[0007] The second problem with radar signal processing of the conventional technology is shown in Figure 2. In the left column of Figure 2, in bad weather, suppression processing of clutter such as sea clutter or rain and snow clutter is executed for radar signals at a high suppression level. As a result, clutter such as sea clutter or rain and snow clutter is appropriately suppressed at close range from the ship, etc., but targets such as small vessels or buoys with weaker reflection strength than the clutter are not displayed, so the ship must be maneuvered with careful lookout.

[0008] In the right column of Figure 2, when the weather improves, the suppression process for clutter such as sea clutter or rain / snow clutter is forgotten to be performed at a low suppression level for the radar signal, but is instead performed at a high suppression level, the same as in bad weather. As a result, clutter such as sea clutter or rain / snow clutter is excessively suppressed in close range to the ship, etc., and targets such as small boats or buoys with weak reflection strength may also be excessively suppressed (in reality, targets such as small boats or buoys with weak reflection strength are present in the right column of Figure 2).

[0009] The third problem with radar signal processing of the conventional technology is shown in Fig. 3. In the left column of Fig. 3, suppression processing of clutter such as sea clutter or rain / snow clutter is performed on the radar signal at a suppression level that allows small targets such as slow-moving ships or buoys (whose intensity is as low as clutter such as sea clutter) to be displayed.

[0010] In the right column of Figure 3, the radar signal is subjected to suppression processing of clutter such as sea clutter or rain / snow clutter, and then correlation processing between scans is performed. As a result, clutter such as sea clutter or rain / snow clutter is properly removed, and small targets such as low-speed ships or buoys are properly extracted, but high-speed targets such as high-speed ships may not be extracted in real time for each scan.

[0011] Therefore, in order to solve the above problems, an object of the present disclosure is to improve the display manner of radar images in radar technology that suppresses clutter such as sea surface clutter or rain / snow clutter, in order to execute clutter suppression processing at an appropriate suppression level, or in order to appropriately extract small targets such as low-speed ships or buoys, and also extract high-speed targets such as high-speed ships in real time. [Means for solving the problem]

[0012] In order to solve the above problem, a first radar image in which clutter suppression processing is performed and a second radar image in which clutter suppression processing is not performed or clutter suppression processing is performed weaker than that of the first radar image are superimposed and displayed. Here, the second radar image is displayed transparently and at the bottom (displayed in colors and multiple gradations that are weakly recognizable), and the first radar image is displayed at the top. Alternatively, the second radar image is displayed with a smaller weighting, and the first radar image is displayed with a larger weighting.

[0013] Specifically, the present disclosure relates to a radar signal processing device comprising: a first radar image output unit that performs clutter suppression processing of both or either of sea surface clutter and rain / snow clutter on a radar signal and outputs a first radar image; a second radar image output unit that does not perform clutter suppression processing of both or either of sea surface clutter and rain / snow clutter on the radar signal, or performs clutter suppression processing weaker than that of the first radar image and outputs a second radar image; and a radar image display unit that causes a radar image display device to display the second radar image transparently and at the bottom and the first radar image at the top, or to display the second radar image with a smaller weighting and the first radar image with a larger weighting, when superimposing the first radar image and the second radar image.

[0014] According to this configuration, in order to execute the clutter suppression process at an appropriate suppression level, the display manner of the radar image can be improved so as to intuitively display the current degree of clutter suppression through a relative comparison between the first radar image and the second radar image.

[0015] The present disclosure also relates to a radar signal processing device, further comprising a clutter suppression display unit that, when, in the second radar image, the range in which the clutter appears around the radar transceiver device is narrower in distance than a predetermined range and, in the first radar image, the degree of clutter suppression is higher than a predetermined degree, causes the radar image display device to display a message indicating that the degree of clutter suppression should be lowered compared to a current degree.

[0016] According to this configuration, the display mode of the radar image can be improved so as to display a warning that the suppression level should be lower when the weather improves compared to when the weather is bad in order to execute the clutter suppression processing at an appropriate suppression level.

[0017] The present disclosure also relates to a radar signal processing device, further comprising a clutter suppression notification unit that notifies the first radar image output unit that a degree of clutter suppression should be lowered compared to a current degree when, in the second radar image, the range in which the clutter appears around the radar transceiver device is narrower in distance than a predetermined range and, in the first radar image, the degree of clutter suppression is higher than a predetermined degree.

[0018] According to this configuration, in order to execute the clutter suppression process at an appropriate suppression level, the display manner of the radar image can be improved by automatically setting the first radar image output unit to execute the process at a lower suppression level when the weather improves compared to when the weather is bad.

[0019] The present disclosure also relates to a radar signal processing device, characterized in that the first radar image output unit performs the clutter suppression processing on the radar signal, does not perform correlation processing between scans, and outputs the first radar image, and the second radar image output unit does not perform the clutter suppression processing on the radar signal, or performs the clutter suppression processing weaker than the first radar image, performs correlation processing between scans, and outputs the second radar image.

[0020] According to this configuration, in order to appropriately extract small targets such as slow ships or buoys, and also to extract high-speed targets such as high-speed ships in real time, a first radar image in which clutter suppression processing is performed but correlation processing between scans is not performed, and a second radar image in which clutter suppression processing is not performed or clutter suppression processing is performed weaker than in the first radar image, and correlation processing between scans is performed can be superimposed and displayed.

[0021] The present disclosure also provides a radar signal processing program for causing a computer to execute each processing step executed by each processing unit included in the above-described radar signal processing device.

[0022] According to this configuration, it is possible to provide a program having the above-described effects.

[0023] The present disclosure also relates to a radar image display device characterized in that, when superimposing the first radar image and the second radar image output by the radar signal processing device described above, the second radar image is displayed transparently and at the bottom and the first radar image is displayed at the top, or the second radar image is displayed with a smaller weighting and the first radar image is displayed with a larger weighting.

[0024] According to this configuration, it is possible to provide a display device having the above-described effects.

[0025] The above disclosed inventions can be combined to the greatest extent possible. Effect of the Invention

[0026] In this way, the present disclosure makes it possible to improve the display manner of radar images in radar technology that suppresses clutter such as sea surface clutter or rain / snow clutter, in order to perform clutter suppression processing at an appropriate suppression level, or to appropriately extract small targets such as slow-moving ships or buoys, while also extracting high-speed targets such as high-speed ships in real time. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a diagram illustrating a first radar signal processing problem in the prior art. [Diagram 2] FIG. 1 is a diagram illustrating a second radar signal processing problem in the prior art. [Diagram 3] FIG. 11 is a diagram illustrating a third radar signal processing problem in the prior art. [Figure 4] FIG. 1 is a diagram illustrating a configuration of a radar system according to the present disclosure. [Diagram 5] FIG. 2 is a diagram showing a procedure for radar signal processing according to the present disclosure. [Figure 6] FIG. 2 is a diagram showing a specific example of a first radar signal processing method of the present disclosure. [Figure 7] FIG. 11 is a diagram showing a specific example of a second radar signal processing method according to the present disclosure. [Figure 8] FIG. 11 is a diagram showing a specific example of a second radar signal processing method according to the present disclosure. [Figure 9] FIG. 11 is a diagram showing a specific example of a third radar signal processing method of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0029] (Configuration of the radar system of the present disclosure) The configuration of the radar system disclosed herein is shown in Fig. 4. The procedure of radar signal processing disclosed herein is shown in Fig. 5. The radar system R includes a radar transceiver A, a radar signal processing device S, and a radar image display device D. The radar signal processing device S includes a first radar image output unit 1, a second radar image output unit 2, a radar image display unit 3, a clutter suppression setting unit 4, a clutter suppression display unit 5, and a clutter suppression notification unit 6, and can be realized by installing the radar signal processing program shown in Fig. 5 on a computer.

[0030] The radar system R detects targets such as ships or buoys by suppressing clutter such as sea clutter and / or rain / snow clutter. The radar transceiver A transmits radar irradiated waves, receives radar reflected waves, and outputs radar signals. The radar signal processing device S performs clutter suppression processing and correlation processing between scans on the radar signal, and outputs a radar image. The radar image display device D displays the radar image.

[0031] First, a specific example of a first radar signal processing method of the present disclosure for performing clutter suppression processing at an appropriate suppression level will be described. Next, a specific example of a second radar signal processing method of the present disclosure for performing clutter suppression processing at an appropriate suppression level will be described. Finally, a specific example of a third radar signal processing method of the present disclosure for appropriately extracting small targets such as low-speed ships or buoys and also extracting high-speed targets such as high-speed ships in real time will be described.

[0032] (First specific example of radar signal processing according to the present disclosure) A specific example of the first radar signal processing of the present disclosure is shown in Fig. 6. The first radar image output unit 1 and the second radar image output unit 2 execute different processes as described below, but have in common the point that they execute a process of removing interference waves from other radar systems.

[0033] The first radar image output unit 1 performs clutter suppression processing on the radar signal, such as both or either of sea surface clutter and rain / snow clutter, and outputs the first radar image (step S1). Here, the first radar image output unit 1 performs clutter suppression processing according to a user setting of a clutter suppression level in the clutter suppression setting unit 4.

[0034] The second radar image output unit 2 outputs the second radar image without performing clutter suppression processing of either or both of sea surface clutter and rain / snow clutter on the radar signal, or by performing clutter suppression processing weaker than that of the first radar image (step S2). In other words, the second radar image output unit 2 only performs the minimum necessary processing (for example, processing to remove interference waves from other radar systems, etc.).

[0035] The radar image display unit 3 causes the radar image display device D to display the first radar image and the second radar image in a superimposed manner (step S3 or step S4).

[0036] Specifically, the radar image display unit 3 displays the second radar image transparently and at the bottom (displayed in a color tone and multiple gradations that can be more weakly recognized), and displays the first radar image at the top (displayed in a color tone and multiple gradations that can be more strongly recognized) (step S3).

[0037] Alternatively, the radar image display unit 3 displays the second radar image with a smaller weighting (for example, by multiplying the number of gradations of each pixel by a) and displays the first radar image with a larger weighting (for example, by multiplying the number of gradations of each pixel by 1-a (>a)) (step S4).

[0038] In the left column of Fig. 6, in the second radar image displayed transparently at the bottom, clutter suppression processing such as sea clutter or rain / snow clutter is not performed at all, or is performed weakly compared to the first radar image. As a result, clutter such as sea clutter or rain / snow clutter is displayed over a wide distance range in the close range from the ship, etc.

[0039] In the middle column of Fig. 6, in the first radar image displayed at the top, suppression processing of clutter such as sea clutter or rain and snow clutter is executed according to the user settings. Then, clutter such as sea clutter or rain and snow clutter is suppressed in the close range from the ship etc., and the main bang (leakage signal from the transmitter to the receiver) is displayed in a narrow range in terms of distance.

[0040] In the right column of Fig. 6, the first and second radar images are superimposed, and the current clutter suppression level is displayed intuitively based on whether the clutter display range in the first radar image is closer or closer in distance than the clutter display range in the second radar image.

[0041] When the clutter display range of the first radar image is too narrow in distance compared to the clutter display range of the second radar image, the current clutter suppression level is too high. Therefore, by lowering the new clutter suppression level compared to the current clutter suppression level, it is possible to reduce the possibility that targets such as small vessels or buoys with weak reflection strength are being excessively suppressed.

[0042] When the clutter display range of the first radar image is too close in distance compared to the clutter display range of the second radar image, the current clutter suppression level is too low. Therefore, by increasing the new clutter suppression level compared to the current clutter suppression level, it is possible to reduce the possibility that clutter and targets are not appropriately distinguished from each other.

[0043] In this way, in order to perform clutter suppression processing at an appropriate suppression level, the display manner of the radar image can be improved so as to intuitively display the current degree of clutter suppression through a relative comparison between the first radar image and the second radar image.

[0044] (Specific example of second radar signal processing according to the present disclosure) A specific example of the second radar signal processing of the present disclosure is shown in Figures 7 and 8. In the second radar signal processing of the present disclosure, the first radar image output unit 1, the second radar image output unit 2, and the radar image display unit 3 execute the same processing as in the first radar signal processing of the present disclosure.

[0045] Then, when the clutter appearance range around the radar transceiver A in the second radar image is narrower in distance than a predetermined range (step S5, YES) and when the degree of clutter suppression in the first radar image is higher than a predetermined level (step S6, YES), the clutter suppression display unit 5 causes the radar image display device D to display a message indicating that the degree of clutter suppression should be lowered compared to the current level (step S7).On the other hand, when the clutter suppression display unit 5 judges NO in step S5, or when the clutter suppression display unit 5 judges YES in step S5 and NO in step S6, it does not execute step S7 and ends the radar signal processing.

[0046] Alternatively, when the range in which clutter appears around the radar transceiver A in the second radar image is narrower in distance than a predetermined range (step S5, YES) and the degree of clutter suppression in the first radar image is higher than a predetermined level (step S6, YES), the clutter suppression notifying unit 6 notifies the first radar image output unit 1 that the degree of clutter suppression should be lowered compared to the current level (step S8).On the other hand, when the clutter suppression notifying unit 6 judges NO in step S5, or when the clutter suppression notifying unit 6 judges YES in step S5 and NO in step S6, it does not execute step S8 and ends radar signal processing.

[0047] In the left columns of Figures 7 and 8, in bad weather, the user increases the clutter suppression level to adjust to an image with less clutter. Then, in the first and second radar images displayed in a superimposed manner, the degree of clutter suppression in the first radar image is moderately high compared to a predetermined level (e.g., a knob level value of 50% or more) (step S6, YES), and the display range of the clutter in the second radar image is wider in distance compared to a predetermined range (e.g., around the ship itself) (step S5, NO). This indicates that clutter is suppressed in the vicinity of the ship itself, etc., and that targets such as small vessels or buoys with weak reflection strength may be suppressed together with the clutter, but this is not a problem because it is the result of the user adjusting to an image with less clutter (in reality, there are no targets such as small vessels or buoys with weak reflection strength in the left columns of Figures 7 and 8).

[0048] In the middle columns of Figures 7 and 8, when the weather improves, the user forgets to lower the clutter suppression level. Then, in the first and second radar images displayed in a superimposed manner, the degree of clutter suppression in the first radar image is excessively high compared to a predetermined level (e.g., a knob level value of 50% or more) (step S6, YES), and the display range of the clutter in the second radar image is narrower in distance compared to a predetermined range (e.g., around the ship, etc.) (step S5, YES). This indicates that the degree of clutter suppression is excessively high in a short distance from the ship, etc., even though clutter suppression is not necessary, and there is a possibility that targets such as small vessels or buoys with weak reflection intensity are excessively suppressed (in reality, in the middle columns of Figures 7 and 8, targets such as small vessels or buoys with weak reflection intensity exist, and targets such as small vessels or buoys with weak reflection intensity are displayed only at low intensity in the second radar image).

[0049] In the right column of Fig. 7, when the weather improves, a warning is displayed to the effect that the degree of clutter suppression should be lowered compared to the current level in the first and second radar images displayed in a superimposed manner (step S7). This allows the user to remember to lower the clutter suppression level.

[0050] In the right column of Fig. 8, when the weather improves, an automatic setting is made to lower the degree of clutter suppression in the first and second radar images displayed in a superimposed manner compared to the current level (step S8). This makes it possible to reduce the possibility that targets such as small vessels or buoys with weak reflection intensity are excessively suppressed in close range from the ship, etc. (In reality, in the right column of Fig. 8, targets such as small vessels or buoys with weak reflection intensity are present, and targets such as small vessels or buoys with weak reflection intensity are displayed with high intensity not only in the second radar image but also in the first radar image, and clutter is displayed only in a narrow distance range).

[0051] In this way, the display mode of the radar image can be improved so as to display a warning that the suppression level should be lower when the weather improves than when the weather is bad in order to perform the clutter suppression processing at an appropriate suppression level.

[0052] Alternatively, in order to execute the clutter suppression process at an appropriate suppression level, the display manner of the radar image can be improved so that the first radar image output unit 1 is automatically set to execute the process at a lower suppression level when the weather improves compared to when the weather is bad.

[0053] (Third specific example of radar signal processing according to the present disclosure) A specific example of the third radar signal processing of the present disclosure is shown in Fig. 9. The first radar image output unit 1 and the second radar image output unit 2 execute different processes as described below, but have in common the fact that they execute a process of removing interference waves from other radar systems.

[0054] The first radar image output unit 1 performs clutter suppression processing on the radar signal, does not perform correlation processing between scans, and outputs the first radar image (step S1). Here, it is desirable for the first radar image output unit 1 to set an appropriate clutter suppression level so that high-speed targets such as high-speed ships can be extracted in real time.

[0055] The second radar image output unit 2 does not perform clutter suppression processing on the radar signal or performs clutter suppression processing weaker than that of the first radar image, performs correlation processing between scans, and outputs the second radar image (step S2). Here, it is desirable for the second radar image output unit 2 to display targets with high reflection intensity in a color tone that makes them more noticeable so that small targets such as slow-moving ships or buoys can be appropriately extracted.

[0056] The radar image display unit 3 causes the radar image display device D to display the first radar image and the second radar image in a superimposed manner (step S3 or step S4).

[0057] Specifically, the radar image display unit 3 displays the second radar image transparently and at the bottom, and displays the first radar image at the top (step S3, right column in FIG. 9).

[0058] Alternatively, the radar image display unit 3 displays the second radar image with a smaller weighting and displays the first radar image with a larger weighting (step S4).

[0059] In the left column of Fig. 9, in the first radar image displayed at the top, clutter suppression processing is performed, but correlation processing between scans is not performed, which increases the possibility that high-speed targets such as high-speed ships are extracted in real time for each scan.

[0060] As in the right column of Fig. 3, in the second radar image displayed transparently at the bottom, correlation processing between scans is performed, but clutter suppression processing is not performed, or clutter suppression processing is performed weakly compared to the first radar image, which can increase the possibility that small targets such as slow-moving ships or buoys are properly extracted.

[0061] In the right column of Fig. 9, in the first and second radar images displayed in a superimposed manner, it is possible to increase the possibility that high-speed targets such as high-speed ships are extracted in real time for each scan, and it is also possible to increase the possibility that small targets such as low-speed ships or buoys are properly extracted. Furthermore, because clutter is properly removed by the clutter suppression process and the correlation process between scans, it is also possible to increase the possibility that targets in the vicinity of the own ship are properly extracted.

[0062] In this way, in order to appropriately extract small targets such as slow ships or buoys, as well as to extract high-speed targets such as high-speed ships in real time, a first radar image in which clutter suppression processing is performed but correlation processing between scans is not performed, and a second radar image in which clutter suppression processing is not performed or clutter suppression processing is performed weaker than in the first radar image, and correlation processing between scans is performed can be superimposed and displayed. [Industrial Applicability]

[0063] The radar signal processing device, radar signal processing program, and radar image display device disclosed herein can improve the display manner of radar images in order to perform suppression processing of clutter such as sea surface clutter or rain / snow clutter at an appropriate suppression level, or to appropriately extract small targets such as slow-moving ships or buoys while also extracting high-speed targets such as high-speed ships in real time. [Explanation of symbols]

[0064] R: Radar system A: Radar transmitter and receiver S: Radar signal processing device D: Radar image display device 1: First radar image output section 2: Second radar image output section 3: Radar image display section 4: Clutter suppression setting section 5: Clutter suppression display section 6: Clutter suppression notification unit

Claims

1. a first radar image output unit that performs a process of suppressing clutter such as sea clutter and / or rain / snow clutter on the radar signal and outputs a first radar image; a second radar image output unit that outputs a second radar image by not performing a clutter suppression process for both or one of sea surface clutter and rain / snow clutter on the radar signal, or by performing the clutter suppression process weaker than that on the first radar image; a radar image display unit that, when causing a radar image display device to superimpose and display the first radar image and the second radar image, displays the second radar image transparently and at a lower part and displays the first radar image at an upper part, or displays the second radar image with a smaller weighting and displays the first radar image with a larger weighting; A radar signal processing device comprising:

2. a clutter suppression display unit that displays, on the radar image display device, a message indicating that the degree of clutter suppression should be lowered compared to a current level, when, in the second radar image, the range in which the clutter appears around the radar transceiver device is narrower in distance than a predetermined range and, in the first radar image, the degree of clutter suppression is higher than a predetermined level; The radar signal processing device according to claim 1 , further comprising:

3. a clutter suppression notification unit that notifies the first radar image output unit that a degree of clutter suppression should be lowered compared to a current degree when, in the second radar image, an appearance range of the clutter around the radar transceiver device is narrower in distance than a predetermined range and, in the first radar image, a degree of clutter suppression is higher than a predetermined degree; The radar signal processing device according to claim 1 , further comprising:

4. the first radar image output unit performs the clutter suppression process on the radar signal, does not perform correlation process between scans, and outputs the first radar image; The second radar image output unit does not perform the clutter suppression process on the radar signal, or performs the clutter suppression process weaker than that on the first radar image, performs correlation processing between the scans, and outputs the second radar image.

4. A radar signal processing device according to claim 1, wherein the first and second signals are transmitted to the radar.

5. A radar signal processing program for causing a computer to execute each processing step executed by each processing unit included in the radar signal processing device according to claim 1.

6. 2. The radar signal processing device according to claim 1, wherein the first radar image and the second radar image are outputted from the radar signal processing device in a superimposed manner, the second radar image is transparently displayed at the bottom and the first radar image is displayed at the top, or the second radar image is displayed with a smaller weighting and the first radar image is displayed with a larger weighting. A radar image display device characterized by the above.

Images