A radar BP imaging method and system considering antenna beam width

Abstract

The invention belongs to the field of radar imaging, and provides a radar BP imaging method considering antenna beam width. The method judges the type of radar according to an imaging scene. If the imaging scene is derived from a ground penetrating radar or a wall-penetrating radar, all points in a plane are processed by Snell's law, and a two-way delay from the radar to an object is obtained according to coordinate information of a refraction point. If the imaging scene is derived from an ordinary radar, the two-way delay from the radar to the object is obtained according to a distance from the radar to a target pixel. An echo signal of a pixel point corresponding to the current radar is obtained in combination with the two-way delay from the radar to the target. The obtained echo signal is pulse compressed in the distance direction, and the echo signals of all pixel points are cumulatively weighted in the azimuth direction to obtain a high-resolution reconstructed image.

Description

Technical Field

[0001] The present invention belongs to the field of radar imaging, and in particular relates to a radar BP imaging method and system taking antenna beam width into consideration. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] At present, the core of mainstream radar technology is the back-projection (BP) algorithm. The back-projection (BP) algorithm is an imaging method based on time-domain processing. When the imaging method models the environment as a layered medium, the BP algorithm can bring a simple and powerful solution to imaging. By calculating the round-trip time delay between the radar and the target and compensating for it, the echo information is synchronized in the time domain and then superimposed on the imaging pixel. The BP algorithm has become one of the most practical imaging methods due to its convenience and robustness. It can be applied to various radar systems and scenarios while achieving high imaging accuracy.

[0004] The traditional BP algorithm has the following disadvantages:

[0005] 1. The BP algorithm has a large amount of calculation, a high computational burden, and is very time-consuming, resulting in a decrease in imaging rate.

[0006] 2. There are many antennas and the cost is high.

[0007] 3. There are artifacts in the imaging background, which reduces the accuracy of target detection, and the clutter generated by environmental factors such as noise affects the image resolution. Summary of the invention

[0008] In order to solve at least one technical problem in the above background technology, the present invention provides a radar imaging BP method and system considering antenna beam width, which increases or decreases the antenna beam width, performs self-amplitude weighting and multiplication weighting on the energy value of the pixel point, reduces the amount of calculation, and improves the imaging quality. During the imaging process, it is not necessary to calculate the time delay of all antennas, and the target can be imaged by calculating the number of antenna beams.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] A first aspect of the present invention provides a radar BP imaging method taking antenna beam width into consideration, comprising:

[0011] Determine the type of radar based on the imaging scene. If the imaging scene comes from ground-penetrating radar or wall-penetrating radar, use Snell's law to process all points in the plane and obtain the two-way delay from the radar to the object based on the coordinate information of the refraction point. If the imaging scene comes from ordinary radar, obtain the two-way delay from the radar to the object based on the distance from the radar to the target pixel.

[0012] Combined with the two-way time delay from the radar to the target, the echo signal of the corresponding pixel point of the current radar is obtained;

[0013] The obtained echo signal is pulse compressed in the range direction, and the echo signals of all pixel points are accumulated and weighted in the azimuth direction to obtain a high-resolution reconstructed image.

[0014] A second aspect of the present invention provides a radar BP imaging device taking antenna beam width into consideration, comprising:

[0015] The two-way delay calculation module is configured to: determine the type of radar according to the imaging scene; if the imaging scene comes from a ground-penetrating radar or a wall-penetrating radar, process all points in the plane through Snell's law, and obtain the two-way delay from the radar to the object according to the coordinate information of the refraction point; if the imaging scene comes from an ordinary radar, obtain the two-way delay from the radar to the object according to the distance from the radar to the target pixel;

[0016] The echo signal generation module is configured to: obtain the echo signal of the pixel point corresponding to the current radar by combining the two-way delay from the radar to the target;

[0017] The high-resolution image reconstruction module is configured to: perform pulse compression on the obtained echo signal in the range direction, and perform cumulative weighting on the echo signals of all pixel points in the azimuth direction to obtain a high-resolution reconstructed image.

[0018] A third aspect of the present invention provides a computer-readable storage medium.

[0019] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps in the radar BP imaging method considering antenna beam width as described above.

[0020] A fourth aspect of the present invention provides a computer device.

[0021] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps in the radar BP imaging method considering antenna beam width as described above are implemented.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] A radar BP method and system considering antenna beam width. The main method is to increase or decrease the antenna beam width, perform self-amplitude weighting and multiplication weighting on the energy value of the pixel point, reduce the amount of calculation, and improve the imaging quality. During the imaging process, it is not necessary to calculate the time delay of all antennas. By calculating more or less antenna beams, the target can be imaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0025] Figure 1 It is a flow chart of a radar BP imaging method taking antenna beam width into consideration provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0029] In order to solve the problems existing in the traditional BP algorithm, the present invention provides a radar BP imaging method and system that considers the antenna beam width. The main method is to increase or decrease the antenna beam width, perform self-amplitude weighting and multiplication weighting on the energy value of the pixel point, reduce the amount of calculation, and improve the imaging quality. During the imaging process, it is not necessary to calculate the time delay of all antennas, and the target can be imaged by calculating more or less antenna beams.

[0030] Embodiment 1

[0031] like Figure 1 As shown, this embodiment provides an improved radar BP imaging method considering antenna beam width, comprising the following steps:

[0032] Step 1: Determine the type of radar based on the imaging scene. If the imaging scene comes from ground-penetrating radar or wall-penetrating radar, use Snell's law to process all points in the plane and obtain the two-way delay from the radar to the object based on the coordinate information of the refraction point. If the imaging scene comes from ordinary radar, obtain the two-way delay from the radar to the object based on the distance from the radar to the target pixel.

[0033] Step 2: Combine the two-way time delay from the radar to the target to obtain the echo signal of the pixel point corresponding to the current radar;

[0034] Step 3: Perform pulse compression on the obtained echo signal in the range direction, and perform cumulative weighting on the echo signals of all pixel points in the azimuth direction to obtain a high-resolution reconstructed image.

[0035] The BP imaging algorithm processes each signal individually, and performs interpolation operations on the distance of the received echo signal and pulse compression to focus the target in the imaging scene. During the imaging process, it is ensured that all pixel points can be traversed. If not all pixels are traversed, it returns to the previous stage and re-accumulates weights or recalculates pulse compression.

[0036] The above process is specifically explained by taking different radar applications as examples.

[0037] If the imaging scene comes from ordinary radar, the imaging method includes the following steps:

[0038] (1) Obtain the positional relationship of all pixels in the imaging scene;

[0039] The radar sampling position along the flight is set to (d 1 , d 2 ,...d i ,...d m ), the processed echo signal in the range direction received by the i-th sampling position is {s(i, 1), s(1, 2), ...s(i, j), ...s(i, n)}, and the m directional sampling points and n range sampling points form a two-dimensional echo matrix s m×n .

[0040] Directly calculate the distance from the radar antenna to the target pixel, the calculation formula is:

[0041]

[0042] Among them, x r is the horizontal coordinate of the radar, (x, y) is the pixel point in the scene;

[0043] (2) Calculate the two-way delay from the antenna to the target based on the positional relationship of all pixels, including:

[0044] The imaging scene containing the target is divided into a grid at an appropriate resolution. Each pixel is represented by a two-dimensional coordinate p(x, y). The transmitted signal in each azimuth direction is reflected by the corresponding reflection at the pixel point at the sampling position d in the azimuth direction. i When the time delay corresponding to the pixel point p(x, y) is t(i, x, y), we can i The obtained distance is delayed by t(i, x, y) in the sampling signal to obtain the reflection signal corresponding to the pixel point p(x, y).

[0045] The calculation formula for the two-way delay from the antenna to the target is:

[0046]

[0047] Among them, x r is the horizontal coordinate of the radar, c is the speed of light, x is the horizontal coordinate of the pixel point in the scene, and y is the vertical coordinate of the pixel point in the scene.

[0048] (3) According to the two-way delay from the antenna to the target, the echo signal of the corresponding pixel point of the current radar is obtained as:

[0049] s(t)=σ·p(t-τ) (3)

[0050] The obtained echo data is pulse compressed through a matched filter:

[0051]

[0052] Among them, p*(t) is the conjugate of p(t), and r(t) is the compressed data;

[0053] (4) The compressed data can be used to construct a rough image covering the detection area. In order to obtain an image of all pixels, the signal component corresponding to each image pixel can be obtained by interpolation. Each directional radar sampling point and pixel point in the imaging scene can be traversed, and the echo signal corresponding to each pixel point is accumulated and weighted to obtain a two-dimensional high-resolution imaging result of the target.

[0054] The pulse compressed signal is weighted by cumulative multiplication and amplitude weighting, and the high-resolution reconstructed image is obtained as follows:

[0055]

[0056] Among them, α is the weighting function and m is the number of radar directional bits.

[0057] If the imaging scene comes from ground penetrating radar or wall penetrating radar, the following steps are included:

[0058] (1) Obtaining the positional relationship of all points in the imaging scene includes:

[0059] The three-dimensional ground penetrating radar imaging is to reconstruct the image from the two-dimensional motion of the antenna. In the scene configuration, z = 0 is regarded as the boundary between air and soil; the dielectric constant and magnetic permeability of air are set to ε 1 and μ 1 , and the dielectric constant and magnetic permeability of the soil are set to ε 2 and μ 2 , the dielectric constant of dry soil is defined as a constant;

[0060] Assume that the current position of the antenna is (x 1 ,y 1 , 0), the current position of the target is set to (x 3 ,y 3 , z 3 ), the coordinates of the refraction point in the echo path from the radar to the target are set to (x m ,y m , 0), from the radar to the refraction point is the incident electromagnetic wave, and the angle between the incident electromagnetic wave and the normal of the incident surface is set as the incident angle θ α , set the angle between the refraction point and the target and the interface normal as the reflection angle θβ, and set the dielectric constant of the medium through which the electromagnetic wave passes as ε m .

[0061] Get all the points from the radar to the target and get the incident angle θ according to Snell's law α , reflection angle θ β and dielectric constant ε m The relationship between them is:

[0062]

[0063] The abscissa of the refraction point in the echo path from the radar to the target is obtained by subtracting the abscissa of the refraction point to the target from the abscissa of the target on the X-axis:

[0064]

[0065] Among them, x m is the horizontal coordinate of the refraction point, x 3 is the horizontal coordinate of the current position of the target, x 2 It is the horizontal coordinate of the intersection of the line between the radar and the target on the X-axis;

[0066] (2) Calculate the distance from the radar to the refraction point and the distance from the refraction point to the target. The round-trip delay between the radar and the target is obtained by the displacement-velocity formula:

[0067]

[0068] Where H is the height of the radar from the ground, c is the speed of light, and x 1 is the horizontal coordinate of the current position of the radar antenna, y m is the ordinate of the refraction point in the echo path from the radar to the target, y 3 is the ordinate of the current position of the target, z 3 is the Z coordinate of the target;

[0069] (3) However, when reconstructing an image, not all antenna positions have the same effect on the image, because the antenna is not always omnidirectional. Considering that more or less antenna beam width can reduce the computational burden, it is not necessary to calculate the delays of all antennas. Only the delays of the buried target that is obviously located in its beam antenna are calculated, and then the echo corresponding to the pixel point is weighted by the direction position, and then multiplied to obtain high-resolution imaging.

[0070] The reconstructed image is:

[0071]

[0072] Among them, m 1 ,m 2 ,n 1 ,n 2 Represents the number of antennas in three-dimensional space and is determined based on the approximate relationship of actual shallow buried targets.

[0073]

[0074]

[0075]

[0076]

[0077] Among them, θ 3-dB and Determined by antenna catalog.

[0078] According to the improved radar imaging BP algorithm based on self-amplitude weighting and multiplication weighting considering antenna width of the present invention, radar imaging can be performed better. The simulation results of the embodiment of the present invention show that the method of the present invention has a relatively high resolution in a noisy environment compared with other existing technologies, optimizes the imaging results, and more importantly, reduces the amount of calculation and antenna costs, and improves the efficiency of imaging.

[0079] Embodiment 2

[0080] This embodiment provides a radar BP imaging device taking antenna beam width into consideration, including:

[0081] The two-way delay calculation module is configured to: determine the type of radar according to the imaging scene; if the imaging scene comes from a ground-penetrating radar or a wall-penetrating radar, process all points in the plane through Snell's law, and obtain the two-way delay from the radar to the object according to the coordinate information of the refraction point; if the imaging scene comes from an ordinary radar, obtain the two-way delay from the radar to the object according to the distance from the radar to the target pixel;

[0082] The echo signal generation module is configured to: obtain the echo signal of the pixel point corresponding to the current radar by combining the two-way delay from the radar to the target;

[0083] The high-resolution image reconstruction module is configured to: perform pulse compression on the obtained echo signal in the range direction, and perform cumulative weighting on the echo signals of all pixel points in the azimuth direction to obtain a high-resolution reconstructed image.

[0084] Embodiment 3

[0085] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps in the radar BP imaging method considering the antenna beam width as described above are implemented.

[0086] Embodiment 4

[0087] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps in the radar BP imaging method considering the antenna beam width as described above are implemented.

[0088] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) containing computer-usable program code.

[0089] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0090] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0092] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A radar BP imaging method considering antenna beam width, characterized in that: include: Determine the type of radar based on the imaging scene. If the imaging scene comes from ground-penetrating radar or wall-penetrating radar, use Snell's law to process all points in the plane and obtain the two-way delay from the radar to the object based on the coordinate information of the refraction point. If the imaging scene comes from ordinary radar, obtain the two-way delay from the radar to the object based on the distance from the radar to the target pixel. Combined with the two-way time delay from the radar to the target, the echo signal of the corresponding pixel point of the current radar is obtained; The obtained echo signal is pulse compressed in the range direction, and the echo signals of all pixel points are weighted and accumulated along the azimuth direction by increasing or decreasing the antenna beam width to obtain a high-resolution reconstructed image; specifically, it includes: If the imaging scene comes from an ordinary radar, the signal component corresponding to each image pixel is obtained by interpolation, and each directional radar sampling point and pixel point in the imaging scene are traversed. The echo signal corresponding to each pixel point is accumulated and weighted to obtain a two-dimensional high-resolution imaging result of the target. If the imaging scene comes from ground-penetrating radar or wall-penetrating radar, only the time delay of the buried target that is obviously located at its beam antenna is calculated, and the echo corresponding to the pixel point is weighted by the direction position, and then multiplied to obtain high-resolution imaging.

2. A radar BP imaging method considering antenna beam width as claimed in claim 1, characterized in that: If the imaging scene comes from ground penetrating radar or wall-penetrating radar, obtain all points from the radar to the target, and obtain the relationship between the incident angle, reflection angle and dielectric constant according to Snell's law to obtain the horizontal coordinate of the refraction point in the echo path from the radar to the target.

3. A radar BP imaging method considering antenna beam width as claimed in claim 1, characterized in that: If the imaging scene comes from a ground penetrating radar or a wall-penetrating radar, obtaining the two-way delay from the radar to the object according to the coordinate information of the refraction point includes: calculating the distance from the radar to the refraction point and the distance from the refraction point to the target, and obtaining the round-trip delay between the radar and the target through the displacement-velocity formula.

4. A radar BP imaging method considering antenna beam width as claimed in claim 1, characterized in that: If the imaging scene comes from an ordinary radar, the imaging scene containing the target is divided into grids according to an appropriate resolution. Each pixel point is represented by a two-dimensional coordinate, and the transmitted signal in each azimuth direction has a corresponding reflected signal at the pixel point.

5. The radar BP imaging method considering antenna beam width as claimed in claim 1, characterized in that: If the imaging scene comes from ground penetrating radar or wall-penetrating radar, the two-way delay from radar to the object is: Where H is the height of the radar from the ground, c is the speed of light, and x m is the abscissa of the refraction point in the echo path from the radar to the target, y m is the ordinate of the refraction point in the echo path from the radar to the target, x1 is the abscissa of the current position of the radar antenna, y1 is the ordinate of the current position of the radar antenna, x3 is the abscissa of the current position of the target, y3 is the ordinate of the current position of the target, z3 is the Z coordinate of the target, ε m is the dielectric constant.

6. A radar BP imaging method considering antenna beam width as claimed in claim 1, characterized in that: If the imaging scene comes from an ordinary radar, the two-way delay from the radar to the object is: Among them, x r is the horizontal coordinate of the radar, c is the speed of light, x is the horizontal coordinate of the pixel point in the scene, and y is the vertical coordinate of the pixel point in the scene.

7. A radar BP imaging device taking antenna beam width into consideration, characterized in that: include: The two-way delay calculation module is configured to: determine the type of radar according to the imaging scene; if the imaging scene comes from a ground-penetrating radar or a wall-penetrating radar, process all points in the plane through Snell's law, and obtain the two-way delay from the radar to the object according to the coordinate information of the refraction point; if the imaging scene comes from an ordinary radar, obtain the two-way delay from the radar to the object according to the distance from the radar to the target pixel; The echo signal generation module is configured to: obtain the echo signal of the pixel point corresponding to the current radar by combining the two-way delay from the radar to the target; The high-resolution image reconstruction module is configured to: perform pulse compression on the obtained echo signal in the range direction, and multiply and weight the echo signals of all pixel points in the azimuth direction by increasing or decreasing the antenna beam width to obtain a high-resolution reconstructed image; specifically, it includes: If the imaging scene comes from an ordinary radar, the signal component corresponding to each image pixel is obtained by interpolation, and each directional radar sampling point and pixel point in the imaging scene are traversed. The echo signal corresponding to each pixel point is accumulated and weighted to obtain a two-dimensional high-resolution imaging result of the target. If the imaging scene comes from ground-penetrating radar or wall-penetrating radar, only the time delay of the buried target that is obviously located at its beam antenna is calculated, and the echo corresponding to the pixel point is weighted by the direction position, and then multiplied to obtain high-resolution imaging.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps in a radar BP imaging method considering antenna beam width as described in any one of claims 1 to 6 are implemented.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps in the radar BP imaging method considering antenna beam width as described in any one of claims 1 to 6 are implemented.

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