A radar two-dimensional imaging method based on target HRRP

Abstract

The application discloses a radar two-dimensional imaging method based on target HRRP, which comprises the following steps: acquiring one-dimensional range images of a target to be imaged at multiple different preset angles; each one-dimensional range image comprises multiple scattering points of the target to be imaged and the radial distance of each scattering point from a radar; multiple strong scattering points are selected from each one-dimensional range image; the two-dimensional coordinates of each strong scattering point are determined according to the multiple different preset angles, the multiple strong scattering points and the radial distance of each strong scattering point; and the image of the target to be imaged is determined according to the two-dimensional coordinates of the multiple strong scattering points. The application does not require a large amount of Doppler data, and has simpler principle, more convenient operation and better imaging effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radar imaging, and particularly relates to a radar two-dimensional imaging method based on target HRRP. BACKGROUND

[0002] Radar is used to detect targets by radio and determine their positions in space. After years of development, the ability of radar to obtain information has been growing, but in the actual application of radar systems, one difficulty to be overcome is how to reliably detect and identify air, ground and sea targets at a greater distance. Radar imaging technology enables modern radars to obtain detailed information about the shape and structure of targets, thereby facilitating target identification. In recent years, target identification based on one-dimensional range profile and imaging technology have been widely and deeply studied, however, one-dimensional range profile is essentially the projection distribution of target scattering centers on the radar line of sight, and carries insufficient information and is sensitive to target attitude changes. Therefore, it is very important to study a radar two-dimensional imaging method based on one-dimensional range profile.

[0003] At present, some radar imaging schemes exist in the related art, but in these radar imaging schemes, Doppler shift data are usually needed, and there is a certain degree of difficulty and complexity. SUMMARY

[0004] In order to solve the above problems existing in the related art, the application provides a radar two-dimensional imaging method based on target HRRP. The technical problem to be solved by the application is solved by the following technical scheme:

[0005] The application provides a radar two-dimensional imaging method based on target HRRP, comprising:

[0006] Obtaining one-dimensional range profiles of a target to be imaged at a plurality of different preset angles; each one-dimensional range profile at a preset angle comprises a plurality of scattering points of the target to be imaged and a radial distance of each scattering point from the radar;

[0007] Screening a plurality of strong scattering points from each one-dimensional range profile at a preset angle;

[0008] Determining two-dimensional coordinates of each strong scattering point according to the plurality of different preset angles, the plurality of strong scattering points and the radial distance of each strong scattering point;

[0009] Determining an image of the target to be imaged according to the two-dimensional coordinates of the plurality of strong scattering points.

[0010] In some embodiments, screening a plurality of strong scattering points from each one-dimensional range profile at a preset angle comprises:

[0011] For each preset angle one-dimensional distance image, find the peak value of the one-dimensional distance image at that preset angle, and use the product of the peak value and the preset coefficient as the threshold value corresponding to the one-dimensional distance image at that preset angle;

[0012] Based on the threshold value, multiple scattering points greater than or equal to the threshold value are selected from the scattering points contained in the one-dimensional distance image at the preset angle, and these are used as multiple strong scattering points selected from the one-dimensional distance image at the preset angle.

[0013] In some embodiments, the multiple preset angles include: a first preset angle, a second preset angle, and a third preset angle; wherein, when the radar is at the first preset angle, the radar is coaxial with the target to be imaged; when the radar is at the second preset angle, the radar is located on one side of the axis of the target to be imaged; and when the radar is at the third preset angle, the radar is located on the other side of the axis of the target to be imaged.

[0014] In some embodiments, the two-dimensional coordinates of each strong scattering point are determined based on multiple different preset angles, multiple strong scattering points, and the radial distance of each strong scattering point, including:

[0015] Based on multiple different preset angles, multiple strong scattering points, and the radial distance of each strong scattering point, a relationship model is determined between multiple strong scattering points and multiple different preset angles and multiple strong scattering points.

[0016] By solving the relational model using least squares, a coordinate matrix corresponding to multiple strong scattering points is obtained.

[0017] The two-dimensional coordinates of each strong scattering point are decomposed from the coordinate matrix.

[0018] In some embodiments, the relational model is expressed as follows:

[0019]

[0020] Where C is the coordinate matrix, M is the total number of strong scattering points, M is an integer greater than or equal to 2, l = 1, 2, ..., M, and x(l) and y(l) are the x and y coordinates in the two-dimensional coordinates of the l-th strong scattering point, respectively; and It can be any two of the first preset angle, the second preset angle, and the third preset angle; The radial distance from the radar to the l-th strong scattering point in the one-dimensional range image at the second preset angle. T is the radial distance from the radar to the l-th strong scattering point in the one-dimensional range image at the third preset angle, where T is the transpose symbol.

[0021] In some embodiments, acquiring one-dimensional distance images of the target to be imaged at multiple different preset angles includes:

[0022] Radar signals are transmitted to the target to be imaged at each preset angle, and a one-dimensional range image of the target to be imaged at each preset angle is determined based on the echo signal reflected by the target to be imaged, thus obtaining a one-dimensional range image of the target to be imaged at multiple different preset angles.

[0023] In some embodiments, acquiring one-dimensional distance images of the target to be imaged at multiple different preset angles includes:

[0024] Establish a physical model of the target to be imaged;

[0025] The physical model is imported into the electromagnetic simulation software, and the full-angle domain one-dimensional range image of the target to be imaged is obtained through the electromagnetic simulation software. The full-angle domain one-dimensional range image includes: multiple scattering points of the target to be imaged, and the radial distance of each scattering point from the radar.

[0026] From the full-angle one-dimensional range image of the target to be imaged, select multiple one-dimensional range images at different preset angles.

[0027] In some embodiments, determining an image of the target to be imaged based on the two-dimensional coordinates of multiple strong scattering points includes:

[0028] Based on the two-dimensional coordinates of multiple strong scattering points, the multiple strong scattering points are displayed, and the image composed of the multiple strong scattering points is used as the image of the target to be imaged.

[0029] In some embodiments, the physical model is imported into electromagnetic simulation software, and a full-angle one-dimensional range image of the target to be imaged is obtained through the electromagnetic simulation software, including:

[0030] Import the physical model into the electromagnetic simulation software, and input the preset simulation information and the direction angle from 0° to 360° into the electromagnetic simulation software;

[0031] Based on the physical model, preset simulation information, and azimuth angles from 0° to 360°, electromagnetic simulation software is used to obtain a one-dimensional range image of the target to be imaged from 0° to 360°.

[0032] In some embodiments, the preset coefficient is a number between 0 and 1.

[0033] The present invention has the following beneficial technical effects:

[0034] This invention obtains a one-dimensional range image of a target through electromagnetic simulation. Compared to existing methods that convert RCS data into a one-dimensional range image using MATLAB programs, the one-dimensional range image obtained by this invention has higher reliability and can be directly extracted without calculating the radial distance corresponding to the range unit, thus improving efficiency. Furthermore, by analyzing the relationship between the angle between the radar line of sight and the target, the radial distance, and the target's true two-dimensional coordinates, the two-dimensional coordinates are separated based on the obtained relationship, and the image is obtained from the two-dimensional coordinates. Compared to current two-dimensional imaging methods, this method does not require a large amount of Doppler data, and its principle is simpler, the operation is easier, and the imaging effect is better.

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0036] Figure 1 A flowchart of a radar two-dimensional imaging method based on target HRRP provided in an embodiment of the present invention;

[0037] Figure 2 A schematic diagram of an exemplary flat-bottomed cone provided for embodiments of the present invention;

[0038] Figure 3 A schematic diagram showing the dimensions of an exemplary physical model of a flat-bottomed cone provided for an embodiment of the present invention;

[0039] Figure 4 An exemplary flat-bottomed cone provided in this embodiment of the invention has a full-angle domain one-dimensional range image with a pitch angle of 90° and an azimuth angle of 0° to 360°.

[0040] Figure 5 An exemplary flat-bottomed cone provided in this embodiment of the invention has a one-dimensional range image with a pitch angle of 90° and an azimuth angle of 0° to 90°.

[0041] Figure 6 A schematic diagram of the projection of an exemplary strong scattering point A in the radial direction of a radar, provided for an embodiment of the present invention;

[0042] Figure 7 An exemplary two-dimensional radar target imaging image based on a one-dimensional range image at 0°, 45°, and 315°, provided for embodiments of the present invention;

[0043] Figure 8 An exemplary two-dimensional radar target imaging image based on a one-dimensional range image at 0°, 30°, and 315°, provided for embodiments of the present invention;

[0044] Figure 9 An exemplary two-dimensional radar target imaging image based on a one-dimensional range image at 0°, 30°, and 330° is provided for embodiments of the present invention. Detailed Implementation

[0045] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0046] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0047] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0048] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0049] Currently, several technical solutions exist for radar-based two-dimensional target imaging. For example, a two-dimensional inverse synthetic aperture radar (ISAR) imaging method (hereinafter referred to as Method 1) utilizes missing target echo data, performs azimuth interpolation, determines whether the processed signal needs repair and improvement to obtain a one-dimensional range image, then performs envelope alignment and correction on the one-dimensional range image to obtain a translationally compensated echo, and finally performs azimuth compression to obtain a two-dimensional ISAR image. Another example is a two-dimensional radar target imaging method based on synthetic aperture (hereinafter referred to as Method 2), which obtains a focused image by correcting SAR data, performing range compensation, azimuth frequency domain high-order term compensation, azimuth frequency domain high-order phase filtering, azimuth time domain high-order term compensation, and azimuth tilt correction. However, Method 1 obtains a one-dimensional range image of the target by processing missing target echo data, without considering whether the incompleteness of the echo data affects the generation of the one-dimensional range image, thus affecting subsequent two-dimensional imaging. Furthermore, Method 1 requires Doppler shift data, which is unavailable in many real-world scenarios, significantly reducing its applicability. Method 2, on the other hand, forms range cells through range compression, obtaining resolution in the range direction, i.e., a one-dimensional range image. In the azimuth direction, points in different azimuth directions within the same range cell can be distinguished using different Doppler shift data. Like Method 1, Method 2 also requires Doppler shift data, thus presenting challenges and complexities in hardware implementation and data acquisition. Moreover, SAR relies on the radar moving with the aircraft while the ground target remains stationary, limiting its operation to side-looking and oblique-looking scenarios, and restricting it to small-angle imaging.

[0050] Figure 1 This is a flowchart of a radar two-dimensional imaging method based on a high-resolution range profile (HRRP) provided in an embodiment of the present invention. This method can be executed by radar equipment, such as... Figure 1 As shown, the method includes the following steps:

[0051] S101. Acquire one-dimensional range images of the target to be imaged at multiple different preset angles; each preset angle one-dimensional range image includes: multiple scattering points of the target to be imaged, and the radial distance of each scattering point from the radar.

[0052] Here, the target to be imaged can be any object. Multiple different preset angles are equivalent to multiple different preset orientations; for example, there can be three different preset orientations.

[0053] In some embodiments, radar signals can be transmitted to the target at each preset angle, and a one-dimensional range image of the target at each preset angle can be determined based on the echo signal reflected by the target, thus obtaining one-dimensional range images of the target at multiple different preset angles. In some embodiments, a physical model of the target can also be established, and the physical model can be imported into electromagnetic simulation software. The electromagnetic simulation software can be used to obtain a one-dimensional range image of the target across the entire angular domain (0° to 360°). Then, multiple one-dimensional range images at different preset angles can be selected from the one-dimensional range images of the target across the entire angular domain.

[0054] For example, the multiple different preset angles can be a first preset angle, a second preset angle, and a third preset angle; wherein, when the radar is at the first preset angle, the radar is coaxial with the target to be imaged; when the radar is at the second preset angle, the radar is located on one side of the axis of the target to be imaged; and when the radar is at the third preset angle, the radar is located on the other side of the axis of the target to be imaged.

[0055] Here, the one-dimensional range profile of the target to be imaged includes: multiple scattering points of the target to be imaged, and the radial distance of each scattering point from the radar.

[0056] S102. Select multiple strong scattering points from the one-dimensional distance image at each preset angle.

[0057] Here, for each one-dimensional distance image at a preset angle, the peak value of the one-dimensional distance image at that preset angle can be found, and the product of the peak value and the preset coefficient α can be used as the threshold value corresponding to the one-dimensional distance image at that preset angle. Based on the threshold value, multiple scattering points greater than or equal to the threshold value are selected from the scattering points contained in the one-dimensional distance image at that preset angle, and these are used as multiple strong scattering points selected from the one-dimensional distance image at that preset angle.

[0058] For example, the preset coefficient α can be any number from 0.5 to 0.6; and M strong scattering points can be found from the one-dimensional distance image of each preset angle, where M is an integer greater than or equal to 2.

[0059] S103. Determine the two-dimensional coordinates of each strong scattering point based on multiple different preset angles, multiple strong scattering points, and the radial distance of each strong scattering point.

[0060] Here, a relationship model between multiple strong scattering points and multiple different preset angles and multiple strong scattering points and their radial distances can be determined based on multiple different preset angles, multiple strong scattering points and the radial distance of each strong scattering point. The relationship model is solved by least squares to obtain a coordinate matrix that corresponds to multiple strong scattering points. The two-dimensional coordinates of each strong scattering point are decomposed from the coordinate matrix.

[0061] Specifically, the expression for the relational model is: Where C is the coordinate matrix, M is the total number of strong scattering points, M is an integer greater than or equal to 2, l = 1, 2, ..., M, and x(l) and y(l) are the x and y coordinates in the two-dimensional coordinates of the l-th strong scattering point, respectively; and It can be any two of the first preset angle, the second preset angle, and the third preset angle; The radial distance from the radar to the l-th strong scattering point in the one-dimensional range image at the second preset angle. T is the radial distance from the radar to the l-th strong scattering point in the one-dimensional range image at the third preset angle, where T is the transpose symbol.

[0062] Here, the analysis process for obtaining the expression of the above relational model is as follows:

[0063] When there are M strong scattering points of the target to be imaged, let the two-dimensional coordinates of any strong scattering point A be S. l (x(l), y(l)), l = 1, 2, ..., M, where the center of the target to be imaged is located at the origin O of the two-dimensional coordinate system. Let the angle between the radar line of sight and the target to be imaged be θ. The radial distance of the strong scattering point A on the radar is: Similarly, let the angle between the radar line of sight and the target be... The radial distance of the strong scattering point A on the radar is: Therefore, assuming the radar observes the target N times in N different directions (i.e., corresponding to different angles), let the angle between the line of sight and the target be θ in each observation. Let the radial distance of the strong scattering point A in different directions be... Then we have: Furthermore, D1 = B1·S. When there are many observation directions, the computational workload of the equations is very large. Considering that only two equations are needed to determine the two-dimensional coordinates of a strong scattering point, the above equation can be simplified to: The two-dimensional coordinates of the strong scattering point A can be calculated using this formula. Since there are M strong scattering points in total, each strong scattering point can be solved using the matrix above. Let the coordinates of any strong scattering point be S. i (x(i),y(i)),i=1,2,...,M, then there is: Furthermore, D² = B²·C; that is:

[0064] According to the least squares principle:

[0065] S104. Determine the image of the target to be imaged based on the two-dimensional coordinates of multiple strong scattering points.

[0066] Specifically, radar signals can be transmitted to the target to be imaged at each preset angle, and a one-dimensional range image of the target to be imaged at each preset angle can be determined based on the echo signal reflected by the target to be imaged, thus obtaining a one-dimensional range image of the target to be imaged at multiple different preset angles.

[0067] This invention obtains a one-dimensional range image of the target through electromagnetic simulation. Compared to existing methods that convert RCS data into a one-dimensional range image using MATLAB programs, the obtained range image has higher reliability and can be directly extracted without calculating the radial distance corresponding to the range cell, resulting in higher efficiency. Furthermore, by analyzing the relationship between the one-dimensional range image and the two-dimensional image of the target, this invention requires less Doppler data compared to current two-dimensional imaging methods, and its principle is simpler, operation is easier, and the imaging effect is better.

[0068] The technical effects of the present invention will be further illustrated below using simulation experimental data.

[0069] Established using electromagnetic simulation software CST Figure 2 The physical model of the flat-bottomed cone is shown, and the dimensional diagram of the flat-bottomed cone model is as follows. Figure 3 As shown. Figure 2 The physical model shown is imported into the electromagnetic simulation software CST. Then, a solver is selected (e.g., the high-frequency asymptotic solver), the mode is set to range image mode, the start and end frequencies of the step frequency signal are set to 7 GHz to 13 GHz, the elevation angle is set to 90°, the azimuth angle is set to 0° to 360°, and the resolution is set to 0.1°. The simulation then yields a one-dimensional range image of the flat-bottomed cone across its entire angular domain. Figure 4 As shown. Then, the azimuth angle is reset to 0–90°, and simulation calculations are performed to obtain a one-dimensional range image of the flat-bottomed cone from 0° to 360°, for example... Figure 5 As shown. Figure 4 and Figure 5 As shown, it can be seen that after the radar illuminates the target from any angle, the resulting one-dimensional range image has two strong scattering points. The one-dimensional range images from different angles can be processed to obtain a two-dimensional image of the target.

[0070] Figure 6 This is a schematic diagram of the projection of the strong scattering point A onto the radar radial direction. x′ and x″ represent two directions of radar illumination (i.e., two different angles), and their included angles with the target are respectively... G1 and G2 are the radial projections (radial distances) of the strong scattering point A under x′ and x″, respectively. Clearly, this can be achieved through... The two-dimensional coordinates of the strong scattering point A are solved by considering the radial distance.

[0071] Figure 7 , Figure 8 and Figure 9 These are two-dimensional radar target images based on one-dimensional range profiles from three different directions (three different angles). From... Figures 7 to 9 As can be seen, in order to better reconstruct all the scattering points, one-dimensional range images were selected on both sides of the flat-bottomed conical axis. Figure 7 Select one-dimensional distance images at 0°, 45°, and 315°. Figure 8 Select one-dimensional distance images at 0°, 30°, and 315°. Figure 9 Select one-dimensional distance images at 0°, 30°, and 330°. From... Figures 7 to 9 As can be seen from the final 2D image, there are four scattering points. This is to better separate all the strong scattering points. During the calculation, the coordinates of the cone apex scattering point were separated twice, but this has no impact on the imaging because the two coordinates coincide. From the principle analysis, it can also be concluded that no matter how many times the separation is performed, the coordinates remain the same. Figures 7 to 9 It can also be seen that selecting one-dimensional distance images from different directions has no impact on the final two-dimensional image result, verifying the feasibility of the algorithm and showing good reconstruction of the target size. Figures 7 to 9 We can conclude that the radius of the base circle of the flat-bottomed cone is 60.4 mm and the height is 207 mm.

[0072] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A radar two-dimensional imaging method based on target HRRP, characterized in that, include: Acquire one-dimensional distance images of the target at multiple different preset angles; Each preset angle's one-dimensional range image includes: multiple scattering points of the target to be imaged, and the radial distance of each scattering point from the radar; wherein, the multiple different preset angles include: a first preset angle, a second preset angle, and a third preset angle; wherein, when the radar is at the first preset angle, the radar is coaxial with the target to be imaged; when the radar is at the second preset angle, the radar is located on one side of the axis of the target to be imaged; when the radar is at the third preset angle, the radar is located on the other side of the axis of the target to be imaged; Multiple strong scattering points are selected from the one-dimensional distance image at each preset angle; The two-dimensional coordinates of each strong scattering point are determined based on multiple different preset angles, multiple strong scattering points, and the radial distance of each strong scattering point. The image of the target to be imaged is determined based on the two-dimensional coordinates of multiple strong scattering points; The step of determining the two-dimensional coordinates of each strong scattering point based on multiple different preset angles, multiple strong scattering points, and the radial distance of each strong scattering point includes: Based on multiple different preset angles, multiple strong scattering points, and the radial distance of each strong scattering point, a relationship model is determined between the multiple strong scattering points and the multiple different preset angles and the radial distance of each strong scattering point; the expression of the relationship model is: , It is a coordinate matrix. This represents the total number of multiple strong scattering points. An integer greater than or equal to 2. , and The first The x and y coordinates of a strong scattering point in two dimensions; and It can be any two of the first preset angle, the second preset angle, and the third preset angle; for In the one-dimensional distance image The radial distance of each strong scattering point from the radar. for In the one-dimensional distance image The radial distance of each strong scattering point from the radar. It is the transpose symbol; By solving the relational model using least squares, a coordinate matrix corresponding to multiple strong scattering points is obtained. The two-dimensional coordinates of each strong scattering point are decomposed from the coordinate matrix.

2. The radar two-dimensional imaging method based on target HRRP according to claim 1, characterized in that, Multiple strong scattering points are selected from the one-dimensional distance image at each preset angle, including: For each preset angle one-dimensional distance image, find the peak value of the one-dimensional distance image at that preset angle, and use the product of the peak value and the preset coefficient as the threshold value corresponding to the one-dimensional distance image at that preset angle; Based on the threshold value, multiple scattering points greater than or equal to the threshold value are selected from the scattering points contained in the one-dimensional distance image at the preset angle, and these are used as multiple strong scattering points selected from the one-dimensional distance image at the preset angle.

3. The radar two-dimensional imaging method based on target HRRP according to claim 1, characterized in that, Acquire one-dimensional range images of the target at multiple different preset angles, including: Radar signals are transmitted to the target to be imaged at each preset angle, and a one-dimensional range image of the target to be imaged at each preset angle is determined based on the echo signal reflected by the target to be imaged, thus obtaining a one-dimensional range image of the target to be imaged at multiple different preset angles.

4. The radar two-dimensional imaging method based on target HRRP according to claim 1, characterized in that, Acquire one-dimensional range images of the target at multiple different preset angles, including: Establish a physical model of the target to be imaged; The physical model is imported into the electromagnetic simulation software, and the full-angle domain one-dimensional range image of the target to be imaged is obtained through the electromagnetic simulation software. The full-angle domain one-dimensional range image includes: multiple scattering points of the target to be imaged, and the radial distance of each scattering point from the radar. From the full-angle one-dimensional range image of the target to be imaged, select multiple one-dimensional range images at different preset angles.

5. The radar two-dimensional imaging method based on target HRRP according to claim 1, characterized in that, Based on the two-dimensional coordinates of multiple strong scattering points, the image of the target to be imaged is determined, including: Based on the two-dimensional coordinates of multiple strong scattering points, the multiple strong scattering points are displayed, and the image composed of the multiple strong scattering points is used as the image of the target to be imaged.

6. The radar two-dimensional imaging method based on target HRRP according to claim 4, characterized in that, The physical model is imported into electromagnetic simulation software, and the full-angle one-dimensional range image of the target to be imaged is obtained through the electromagnetic simulation software, including: Import the physical model into the electromagnetic simulation software, and input the preset simulation information and the direction angle from 0° to 360° into the electromagnetic simulation software; Based on the physical model, preset simulation information, and azimuth angles from 0° to 360°, electromagnetic simulation software is used to obtain a one-dimensional range image of the target to be imaged from 0° to 360°.

7. The radar two-dimensional imaging method based on target HRRP according to claim 2, characterized in that, The preset coefficient is a number between 0 and 1.

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