Microwave wavefront modulation forward-looking imaging method and device based on attribute scattering model

Abstract

The present application relates to a microwave wavefront modulation forward-looking imaging method and device based on an attribute scattering model. The method includes: performing random frequency hopping modulation on the wavefront of microwaves emitted by array elements in a radar array, constructing a time-space two-dimensional uncorrelated radiation field of an imaging plane according to the microwave signal emitted by the radar array, discretizing the imaging plane to obtain a discretized grid, obtaining a point scattering model reference matrix corresponding to the imaging plane according to the microwave signal and the reference signal of the center point of the discretized grid, performing one-dimensional and two-dimensional integration on the point scattering model reference matrix to obtain a line scattering model reference matrix and a surface scattering model reference matrix, and then establishing and solving an imaging equation based on a scattering attribute model. Compared with a microwave wavefront modulation forward-looking imaging method that approximates a target as a discrete point scattering model, microwave wavefront modulation forward-looking imaging based on an attribute scattering model can better achieve the reconstruction of the line and surface structure of the target and better restore the geometric structure information of the target.

Description

Technical Field

[0001] The present application relates to the field of microwave imaging technology, and in particular to a microwave wavefront modulation forward-looking imaging method and device based on an attribute scattering model. Background Art

[0002] Existing high-resolution imaging radars such as synthetic aperture radar and inverse synthetic aperture radar mainly work in side-view and oblique imaging modes, and have blind spots in forward-looking imaging. Microwave wavefront modulation forward-looking imaging technology draws on the principle of classical optical correlation imaging and is a high-resolution staring imaging technology. Microwave wavefront modulation forward-looking imaging technology does not rely on the relative motion between the target and the radar system, so it has great application potential in forward-looking imaging scenarios and is expected to complement synthetic aperture and inverse synthetic aperture high-resolution radar imaging technologies.

[0003] The classic microwave wavefront modulation imaging model is based on the assumption that the scattering characteristics of the target can be well approximated as the superposition of discrete point scattering models. However, under the assumption of the point scattering model, microwave wavefront modulation forward-looking imaging technology can only reconstruct a few strong scattering points of the target, but cannot reconstruct the target's geometric structures such as lines and surfaces. Summary of the invention

[0004] Based on this, it is necessary to provide a microwave wavefront modulation forward-looking imaging method and device based on an attribute scattering model that can effectively reconstruct a radar image containing the point, line and surface geometric structure of the target in order to address the above technical problems.

[0005] A microwave wavefront modulation forward-looking imaging method based on an attribute scattering model, the method comprising:

[0006] Constructing a radar array; the radar array includes a plurality of array elements;

[0007] The microwave signal emitted by the radar array is obtained by performing random frequency hopping modulation on the wavefront of the microwave emitted by the array element, and a time-space two-dimensional uncorrelated radiation field of the target imaging plane is constructed according to the microwave signal;

[0008] Discretizing the imaging plane to obtain a discretized grid, obtaining a point scattering model reference matrix corresponding to the imaging plane according to the microwave signal and a reference signal of a center point of the discretized grid, and performing one-dimensional integration and two-dimensional integration on the point scattering model reference matrix to obtain a line scattering model reference matrix and a surface scattering model reference matrix;

[0009] The target scattered echo vector of the array element in the radar array is obtained according to the two-dimensional uncorrelated radiation field in time and space, the imaging equation of the target is obtained according to the target scattered echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix, the imaging equation is solved, and the target imaging is performed.

[0010] In one embodiment, the step of obtaining the microwave signal emitted by the radar array by performing random frequency hopping modulation on the wavefront of the microwave emitted by the array element includes:

[0011] By performing random frequency hopping modulation on the microwave wavefront transmitted by the radar array, the microwave signal transmitted by the radar array is obtained as follows:

[0012]

[0013] Where A is the amplitude of the microwave signal, f c is the carrier frequency, f n,m is the frequency of the mth frequency hopping transmission signal of the nth array element, is the initial phase of the signal transmitted by the nth array element.

[0014] In one embodiment, obtaining a point scattering model reference matrix corresponding to an imaging plane according to the microwave signal and a reference signal of a center point of the discretized grid includes:

[0015] According to the microwave signal and the reference signal of the center point of the discretized grid, the point scattering model reference matrix corresponding to the imaging plane is obtained as follows:

[0016]

[0017] Where c is the microwave propagation speed, R n is the distance between the nth array element and the center of the imaging plane, θ n is the azimuth angle of the nth array element, φ n is the elevation angle of the nth array element, (x i ,y i ) is the coordinate of the i-th point scattering target.

[0018] In one embodiment, performing one-dimensional integration on the point scattering model reference matrix to obtain a line scattering model reference matrix includes:

[0019] The point scattering model reference matrix is ​​integrated in one dimension to obtain the line scattering model reference matrix:

[0020]

[0021] Among them, (x l0 ,y l0 ) is the center coordinate of the line target, L l is the line target length, is the line target angle, D l is the integration area, and j represents the jth line target.

[0022] In one embodiment, performing two-dimensional integration on the point scattering model reference matrix to obtain a surface scattering model reference matrix includes:

[0023] The point scattering model reference matrix is ​​integrated in two dimensions to obtain the surface scattering model reference matrix:

[0024]

[0025] Among them, (x r0 ,y r0 ) is the center coordinate of the surface target, L r is the center length of the surface target, H r is the surface target width, is the surface target angle, and k represents the kth line target.

[0026] In one of the embodiments, the target scattered echo vector of the array element in the radar array is obtained according to the two-dimensional uncorrelated radiation field in time and space, and the imaging equation of the target is obtained according to the target scattered echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix, including:

[0027] According to the two-dimensional uncorrelated radiation field in time and space, the target scattered echo vector of the array element in the radar array is obtained as follows:

[0028] S R =[S R (1),S R (2),...,S R (M)] T

[0029] According to the target scattered echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix, the imaging equation of the target is obtained as follows:

[0030] S R =S p ·σ p +S l ·σ l +S r ·σ r +n

[0031] Among them, S p is the point scattering model reference matrix, S l is the reference matrix of the line scattering model, S r is the reference matrix of the surface scattering model, is the point target scattering coefficient of the reference matrix of the point scattering model to be solved, is the line target scattering coefficient of the reference matrix of the line scattering model to be solved, is the surface target scattering coefficient of the reference matrix of the surface scattering model to be solved, and n is Gaussian white noise.

[0032] In one embodiment, solving the imaging equation to perform target imaging includes:

[0033] The imaging equation is transformed to obtain the objective function:

[0034]

[0035] Among them, λ p is the regularization coefficient of the point target scattering coefficient of the reference matrix of the point scattering model to be solved, λ l is the regularization coefficient of the line target scattering coefficient of the reference matrix of the line scattering model to be solved, λ r is the regularization parameter of the surface target scattering coefficient of the surface scattering reference matrix to be solved.

[0036] The target function is solved by using the alternating direction multiplier method to perform target imaging.

[0037] A microwave wavefront modulation forward-looking imaging device based on an attribute scattering model, the device comprising:

[0038] An array construction module, used to construct a radar array; the radar array includes a plurality of array elements;

[0039] a radiation field construction module, configured to obtain a microwave signal emitted by the radar array by performing random frequency hopping modulation on the wavefront of the microwave emitted by the array element, and to construct a spatiotemporal two-dimensional uncorrelated radiation field of a target imaging plane according to the microwave signal;

[0040] A reference matrix construction module is used to discretize the imaging plane to obtain a discretized grid, obtain a point scattering model reference matrix corresponding to the imaging plane according to the microwave signal and a reference signal of a center point of the discretized grid, and perform one-dimensional integration and two-dimensional integration on the point scattering model reference matrix to obtain a line scattering model reference matrix and a surface scattering model reference matrix;

[0041] The imaging module is used to obtain the target scattered echo vector of the array element in the radar array according to the two-dimensional uncorrelated radiation field in time and space, obtain the imaging equation of the target according to the target scattered echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix, solve the imaging equation, and perform target imaging.

[0042] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0043] Constructing a radar array; the radar array includes a plurality of array elements;

[0044] The microwave signal emitted by the radar array is obtained by performing random frequency hopping modulation on the wavefront of the microwave emitted by the array element, and a time-space two-dimensional uncorrelated radiation field of the target imaging plane is constructed according to the microwave signal;

[0045] Discretizing the imaging plane to obtain a discretized grid, obtaining a point scattering model reference matrix corresponding to the imaging plane according to the microwave signal and a reference signal of a center point of the discretized grid, and performing one-dimensional integration and two-dimensional integration on the point scattering model reference matrix to obtain a line scattering model reference matrix and a surface scattering model reference matrix;

[0046] The target scattered echo vector of the array element in the radar array is obtained according to the two-dimensional uncorrelated radiation field in time and space, the imaging equation of the target is obtained according to the target scattered echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix, the imaging equation is solved, and the target imaging is performed.

[0047] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the following steps:

[0048] Constructing a radar array; the radar array includes a plurality of array elements;

[0049] The microwave signal emitted by the radar array is obtained by performing random frequency hopping modulation on the wavefront of the microwave emitted by the array element, and a time-space two-dimensional uncorrelated radiation field of the target imaging plane is constructed according to the microwave signal;

[0050] Discretizing the imaging plane to obtain a discretized grid, obtaining a point scattering model reference matrix corresponding to the imaging plane according to the microwave signal and a reference signal of a center point of the discretized grid, and performing one-dimensional integration and two-dimensional integration on the point scattering model reference matrix to obtain a line scattering model reference matrix and a surface scattering model reference matrix;

[0051] The target scattered echo vector of the array element in the radar array is obtained according to the two-dimensional uncorrelated radiation field in time and space, the imaging equation of the target is obtained according to the target scattered echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix, the imaging equation is solved, and the target imaging is performed.

[0052] The microwave wavefront modulation forward-looking imaging method and device based on the attribute scattering model mentioned above obtains the microwave signal emitted by the radar array by performing random frequency hopping modulation on the wavefront of the microwave emitted by the array element in the radar array, and constructs the spatiotemporal two-dimensional uncorrelated radiation field of the target imaging plane according to the microwave signal. The difference of the radiation field provides rich information for realizing the resolution of the target, discretizes the imaging plane to obtain a discretized grid, obtains the point scattering model reference matrix corresponding to the imaging plane according to the microwave signal and the reference signal of the center point of the discretized grid, performs one-dimensional integration and two-dimensional integration on the point scattering model reference matrix respectively, obtains the line scattering model reference matrix and the surface scattering model reference matrix, and then establishes and solves the imaging equation based on the scattering attribute model, and obtains the radar image of the target by correlating the echo with the reference signal of the radiation field. Compared with the microwave wavefront modulation forward-looking imaging method that approximates the target as a discrete point scattering model, the microwave wavefront modulation forward-looking imaging based on the attribute scattering model can better realize the reconstruction of the line and surface structure of the target and better restore the geometric structure information of the target. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a diagram of an application scenario of a microwave wavefront modulation forward-looking imaging method based on an attribute scattering model in one embodiment;

[0054] Figure 2 A schematic diagram of a microwave wavefront modulation forward-looking imaging method based on a point scattering model in one embodiment;

[0055] Figure 3 is a simulation comparison result in an embodiment;

[0056] Figure 4 is a simulation comparison result in another embodiment;

[0057] Figure 5 is a structural block diagram of a microwave wavefront modulation forward-looking imaging device based on an attribute scattering model in one embodiment;

[0058] Figure 6 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0060] In one embodiment, Figure 1 As shown, a microwave wavefront modulation forward-looking imaging method based on an attribute scattering model is provided, comprising the following steps:

[0061] Step 102: construct a radar array.

[0062] The radar array includes several array elements, which can be divided into transmitting array elements and receiving array elements. Self-transmitting array elements can be used here.

[0063] Step 104, performing random frequency hopping modulation on the wavefront of microwaves emitted by the array elements to obtain microwave signals emitted by the radar array, and constructing a two-dimensional space-time uncorrelated radiation field of the target imaging plane according to the microwave signals.

[0064] By modulating the electromagnetic wave front, a time-space independent radiation field is constructed. After the radiation field interacts with the detected target, the radar image of the target can be acquired by correlating the target scattered echo with the reference signal of the radiation field.

[0065] Step 106, discretize the imaging plane to obtain a discretized grid, obtain a point scattering model reference matrix corresponding to the imaging plane according to the microwave signal and the reference signal of the center point of the discretized grid, perform one-dimensional integration and two-dimensional integration on the point scattering model reference matrix respectively, and obtain a line scattering model reference matrix and a surface scattering model reference matrix.

[0066] In microwave wavefront modulation forward-looking imaging technology, the imaging area is divided into several discrete grid points. The imaging quality can be further improved by converting the imaging problem into a parameterized solution problem. However, this method is different from the classical wavefront modulation forward-looking imaging technology which simply divides the target into discrete point scattering centers. In this method, the point scattering model, line scattering model and surface scattering model in the attribute scattering model are applied to the classical microwave wavefront modulation forward-looking imaging technology to realize the reconstruction of the target geometric structure.

[0067] Step 108, obtaining the target scattered echo vector of the array element in the radar array according to the two-dimensional uncorrelated radiation field in time and space, obtaining the imaging equation of the target according to the target scattered echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix, solving the imaging equation and performing target imaging.

[0068] By constructing the reference matrices of the point scattering model, line scattering model and surface scattering model, the imaging equation based on the scattering property model is established and solved, and the radar image containing the point, line and surface geometric structure of the target can be effectively reconstructed.

[0069] In the microwave wavefront modulation forward imaging method based on the attribute scattering model, the microwave wavefront modulation forward imaging method and device based on the attribute scattering model randomly perform frequency hopping modulation on the wavefront of microwaves emitted by the array elements in the radar array to obtain the microwave signal emitted by the radar array, and construct the spatiotemporal two-dimensional uncorrelated radiation field of the target imaging plane according to the microwave signal. The difference of the radiation field provides rich information for realizing the resolution of the target, and the imaging plane is discretized to obtain a discretized grid. According to the microwave signal and the reference signal of the center point of the discretized grid, the point scattering model reference matrix corresponding to the imaging plane is obtained, and the point scattering model reference matrix is ​​integrated in one dimension and two dimensions respectively to obtain the line scattering model reference matrix and the surface scattering model reference matrix, and then the imaging equation based on the scattering attribute model is established and solved, and the radar image of the target can be obtained by correlating the echo with the reference signal of the radiation field. Compared with the microwave correlation imaging method that approximates the target as a discrete point scattering model, the microwave wavefront modulation imaging based on the attribute scattering model can better realize the reconstruction of the line and surface structure of the target and better restore the geometric structure information of the target.

[0070] Specifically, the microwave signal emitted by the radar array is obtained by performing random frequency hopping modulation on the wavefront of the microwave emitted by the array element, including:

[0071] The microwave signal emitted by the radar array is obtained by performing random frequency hopping modulation on the transmitted microwave wavefront of the radar array. Assuming that the radar array contains N self-transmitting and self-receiving array elements and transmits M random frequency hopping signals in total, then in the mth frequency hopping, the waveform emitted by the nth array element is:

[0072]

[0073] Where A is the amplitude of the microwave signal, f c is the carrier frequency, f n,m is the frequency of the mth frequency hopping transmission signal of the nth array element, is the initial phase of the signal transmitted by the nth array element.

[0074] Specifically, according to the microwave signal and the reference signal of the center point of the discretized grid, a point scattering model reference matrix corresponding to the imaging plane is obtained, including:

[0075] like Figure 2 As shown, a schematic diagram of a microwave correlation imaging method based on a point scattering model is provided. The imaging plane is discretized into I grid units. Assuming that the scattering point of the target is located at the center of each grid unit in the imaging area, the reference signal of the i-th grid during the m-th frequency hopping is the superposition of all N transmitted signals. That is, according to the microwave signal and the reference signal of the center point of the discretized grid, the reference matrix of the point scattering model corresponding to the imaging plane is obtained as follows:

[0076]

[0077] Where c is the microwave propagation speed, R n is the distance between the nth array element and the center of the imaging plane, θ n is the azimuth angle of the nth array element, φ n is the elevation angle of the nth array element, (x i ,y i ) is the coordinate of the i-th point scattering target.

[0078] Furthermore, the point scattering model reference matrix is ​​integrated in one dimension to obtain the line scattering model reference matrix, including:

[0079] Figure 3 (a) is a schematic diagram of the line scattering model parameters. The scattering response of the line scattering model can be regarded as the one-dimensional integral of the point scattering model response. The reference matrix of the line scattering model is obtained by performing a one-dimensional integral on the point scattering model reference matrix:

[0080]

[0081] Among them, (x l0 ,y l0 ) is the center coordinate of the line target, L l is the line target length, is the line target angle, D l is the integration area, and j represents the jth line target.

[0082] Furthermore, the point scattering model reference matrix is ​​two-dimensionally integrated to obtain the surface scattering model reference matrix, including:

[0083] Figure 3 (b) is a schematic diagram of the surface scattering model parameters. The scattering response of the surface scattering model can be regarded as the two-dimensional integral of the point scattering model response. The reference matrix of the surface scattering model is obtained by performing a two-dimensional integral on the point scattering model reference matrix:

[0084]

[0085] Among them, (x r0 ,y r0 ) is the center coordinate of the surface target, L r is the center length of the surface target, H r is the surface target width, is the surface target angle, and k represents the kth line target.

[0086] In one embodiment, a target scattered echo vector of an array element in a radar array is obtained according to a two-dimensional uncorrelated radiation field in time and space, and an imaging equation of the target is obtained according to the target scattered echo vector, a point scattering model reference matrix, a line scattering model reference matrix, and a surface scattering model reference matrix, including:

[0087] The target scattered echo vector of the array element in the radar array is obtained according to the two-dimensional uncorrelated radiation field in time and space. Assuming that the receiving array element receives M target echoes in total, the target scattered echo vector is:

[0088] S R =[S R (1),S R (2),...,S R (M)] T

[0089] Assume that there are I point scattering targets, J line scattering targets, and K surface scattering targets in the imaging area, and construct reference matrices S p , S l , S r According to the target scattered echo vector, point scattering model reference matrix, line scattering model reference matrix and surface scattering model reference matrix, the imaging equation of the target is obtained as follows:

[0090] S R =S p ·σ p +S l ·σ l +S r ·σ r +n

[0091] Among them, S p is the point scattering model reference matrix, S l is the reference matrix of the line scattering model, S r is the reference matrix of the surface scattering model, is the point target scattering coefficient of the reference matrix of the point scattering model to be solved, is the line target scattering coefficient of the reference matrix of the line scattering model to be solved, is the surface target scattering coefficient of the reference matrix of the surface scattering model to be solved, and n is Gaussian white noise.

[0092] In one embodiment, solving the imaging equation to perform target imaging includes:

[0093] The imaging equation can be regarded as the solution of a convex optimization problem. The objective function obtained by transforming the imaging equation is:

[0094]

[0095] Among them, λ pis the regularization coefficient of the point target scattering coefficient of the reference matrix of the point scattering model to be solved, λ l is the regularization coefficient of the line target scattering coefficient of the reference matrix of the line scattering model to be solved, λ r is the regularization parameter of the surface target scattering coefficient of the surface scattering reference matrix to be solved.

[0096] The alternating direction multiplier method is used to solve the objective function and perform target reconstruction imaging.

[0097] In one embodiment, Figure 3 As shown, the simulation comparison results of this method and other methods are provided. This method is used to randomly hop the transmitted signal of the array radar, and the multi-transmit multi-receive working mode is adopted. The transmitting antenna is a single-row uniform linear array, the number of transmitting array elements is N=61, the array azimuth range is [-2° 2°], the pitch angle is 5°, the carrier frequency of the transmitted signal is 34GHz, the bandwidth is 500MHz, the number of frequency hopping is M=2000, the target distance is 100m, the imaging area is 4m×4m, and the imaging signal-to-noise ratio SNR=20dB.

[0098] Figure 3 (a) and (b) are target scenes, which include two spherical targets, a cylindrical target, and a rectangular target; Figure 3 (c) and (d) are the imaging results of echoes simulated by electromagnetic computing software using the back-projection algorithm; Figure 3 (e) and (f) are the imaging results of the echo calculated by the attribute scattering model echo formula in this method using the back-projection algorithm. The correctness of the target attribute scattering model echo formula can be verified from the consistency of the imaging results; Figure 3 (g) and (h) are the imaging results of the correlation imaging method based on the point scattering model using the sparse Bayesian learning algorithm. Since SBL assumes that the target scattering coefficient satisfies the sparse distribution prior, there are only a few discrete groups of strong scattering points in the imaging results. Figure 3 (i) and (j) are the imaging results of the method of the present invention using the alternating iterative multiplier algorithm. From the results, it can be seen that the microwave wavefront modulation imaging method based on the attribute scattering model can reconstruct the structural information of the target well.

[0099] In one embodiment, Figure 4 As shown, the high-resolution imaging results of this method are provided.

[0100] Figure 4 (a) is a target scene, which contains two spherical targets and two cylindrical targets. The azimuth distance between the two spheres and the two cylinders is 0.1m, and the azimuth range of the antenna array is [-1° 1°]. Figure 4(b) is the result of imaging using the back-projection algorithm based on the echo simulated by the electromagnetic computing software. Due to the limitation of the theoretical resolution of the real aperture, it can be seen that the back-projection algorithm cannot distinguish adjacent targets; Figure 4 (c) is the result of microwave correlation imaging based on the point scattering model. Figure 4 (d) is the microwave wavefront modulation imaging result based on the attribute scattering model. From the imaging results, it can be seen that this method can achieve super-resolution imaging and can accurately reconstruct the structural information of the target.

[0101] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0102] In one embodiment, Figure 5 As shown, a microwave wavefront modulation forward-looking imaging device based on an attribute scattering model is provided, comprising: an array building module, a radiation field building module, a reference matrix building module and an imaging module, wherein:

[0103] Array building blocks for building radar arrays.

[0104] A radar array consists of several array elements.

[0105] The radiation field construction module is used to obtain the microwave signal emitted by the radar array by performing random frequency hopping modulation on the wavefront of the microwave emitted by the array element, and to construct the time-space two-dimensional uncorrelated radiation field of the target imaging plane according to the microwave signal.

[0106] The reference matrix construction module is used to discretize the imaging plane to obtain a discretized grid, obtain the point scattering model reference matrix corresponding to the imaging plane according to the microwave signal and the reference signal of the center point of the discretized grid, and perform one-dimensional and two-dimensional integration on the point scattering model reference matrix to obtain the line scattering model reference matrix and the surface scattering model reference matrix.

[0107] The imaging module is used to obtain the target scattering echo vector of the array element in the radar array according to the two-dimensional uncorrelated radiation field in time and space, obtain the imaging equation of the target according to the target scattering echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix, solve the imaging equation, and perform target imaging.

[0108] Specifically, the radiation field construction module is also used to perform random frequency hopping modulation on the transmitted microwave wavefront of the radar array, so as to obtain the microwave signal emitted by the radar array as follows:

[0109]

[0110] Where A is the amplitude of the microwave signal, f c is the carrier frequency, f n,m is the frequency of the mth frequency hopping transmission signal of the nth array element, is the initial phase of the signal transmitted by the nth array element.

[0111] Specifically, the reference matrix construction is also used to obtain the point scattering model reference matrix corresponding to the imaging plane according to the microwave signal and the reference signal of the center point of the discretized grid:

[0112]

[0113] Where c is the microwave propagation speed, R n is the distance between the nth array element and the center of the imaging plane, θ n is the azimuth angle of the nth array element, φ n is the elevation angle of the nth array element, (x i ,y i ) is the coordinate of the i-th point scattering target.

[0114] Specifically, the reference matrix construction is also used to perform one-dimensional integration on the point scattering model reference matrix to obtain the line scattering model reference matrix, including:

[0115] Perform one-dimensional integration on the point scattering model reference matrix to obtain the line scattering model reference matrix:

[0116]

[0117] Among them, (x l0 ,y l0 ) is the center coordinate of the line target, L l is the line target length, is the line target angle, D l is the integration area, and j represents the jth line target.

[0118] Specifically, the reference matrix construction is also used to perform two-dimensional integration on the point scattering model reference matrix, and the surface scattering model reference matrix is ​​obtained as:

[0119]

[0120] Among them, (x r0 ,y r0 ) is the center coordinate of the surface target, L r is the center length of the surface target, H r is the surface target width, is the surface target angle, and k represents the kth line target.

[0121] Specifically, the imaging module is also used to obtain the target scattered echo vector of the array element in the radar array according to the two-dimensional uncorrelated radiation field in time and space:

[0122] S R =[S R (1),S R (2),...,S R (M)] T

[0123] According to the target scattered echo vector, point scattering model reference matrix, line scattering model reference matrix and surface scattering model reference matrix, the imaging equation of the target is obtained as follows:

[0124] S R =S p ·σ p +S l ·σ l +S r ·σ r +n

[0125] Among them, S p is the point scattering model reference matrix, S l is the reference matrix of the line scattering model, S r is the reference matrix of the surface scattering model, is the point target scattering coefficient of the reference matrix of the point scattering model to be solved, is the line target scattering coefficient of the reference matrix of the line scattering model to be solved, is the surface target scattering coefficient of the reference matrix of the surface scattering model to be solved, and n is Gaussian white noise.

[0126] Specifically, the imaging module is also used to transform the imaging equation to obtain the objective function:

[0127]

[0128] Among them, λ p is the regularization coefficient of the point target scattering coefficient of the reference matrix of the point scattering model to be solved, λ lis the regularization coefficient of the line target scattering coefficient of the reference matrix of the line scattering model to be solved, λ r is the regularization parameter of the surface target scattering coefficient of the surface scattering reference matrix to be solved.

[0129] The alternating direction multiplier method is used to solve the objective function and perform target imaging.

[0130] For the specific definition of the microwave wavefront modulation forward-looking imaging device based on the attribute scattering model, please refer to the definition of the microwave wavefront modulation forward-looking imaging method based on the attribute scattering model mentioned above, which will not be repeated here. Each module in the above-mentioned microwave wavefront modulation forward-looking imaging device based on the attribute scattering model can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0131] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as follows: Figure 6 As shown. The computer device includes a processor, a memory, a network interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a microwave wavefront modulation forward imaging method based on a property scattering model is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0132] Those skilled in the art will understand that Figure 6 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0133] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method in the above embodiment when executing the computer program.

[0134] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method in the above embodiment are implemented.

[0135] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0136] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0137] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A microwave wavefront modulation forward-looking imaging method based on an attribute scattering model, characterized in that: The method comprises: Constructing a radar array; the radar array includes a plurality of array elements; The microwave signal emitted by the radar array is obtained by performing random frequency hopping modulation on the wavefront of the microwave emitted by the array element, and a time-space two-dimensional uncorrelated radiation field of the target imaging plane is constructed according to the microwave signal; Discretizing the imaging plane to obtain a discretized grid, obtaining a point scattering model reference matrix corresponding to the imaging plane according to the microwave signal and a reference signal of a center point of the discretized grid, and performing one-dimensional integration and two-dimensional integration on the point scattering model reference matrix to obtain a line scattering model reference matrix and a surface scattering model reference matrix; The target scattered echo vector of the array element in the radar array is obtained according to the two-dimensional uncorrelated radiation field in time and space, the imaging equation of the target is obtained according to the target scattered echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix, the imaging equation is solved, and the target imaging is performed.

2. The method according to claim 1, characterized in that The method of obtaining the microwave signal emitted by the radar array by performing random frequency hopping modulation on the wavefront of the microwave emitted by the array element comprises: By performing random frequency hopping modulation on the microwave wavefront transmitted by the radar array, the microwave signal transmitted by the radar array is obtained as follows: Where A is the amplitude of the microwave signal, f c is the carrier frequency, f n,m is the frequency of the mth frequency hopping transmission signal of the nth array element, is the initial phase of the signal transmitted by the nth array element.

3. The method according to claim 2, characterized in that The step of obtaining a point scattering model reference matrix corresponding to an imaging plane according to the microwave signal and a reference signal of a center point of the discretized grid comprises: According to the microwave signal and the reference signal of the center point of the discretized grid, the point scattering model reference matrix corresponding to the imaging plane is obtained as follows: Where c is the microwave propagation speed, R n is the distance between the nth array element and the center of the imaging plane, θ n is the azimuth angle of the nth array element, φ n is the elevation angle of the nth array element, (x i ,y i ) is the coordinate of the i-th point scattering target.

4. The method according to claim 3, characterized in that: Performing one-dimensional integration on the point scattering model reference matrix to obtain a line scattering model reference matrix includes: The point scattering model reference matrix is ​​integrated in one dimension to obtain the line scattering model reference matrix: Among them, (x l0 ,y l0 ) is the center coordinate of the line target, L l is the line target length, is the line target angle, D l is the integration area, j represents the jth line target.

5. The method according to claim 4, characterized in that Performing two-dimensional integration on the point scattering model reference matrix to obtain a surface scattering model reference matrix includes: The point scattering model reference matrix is ​​integrated in two dimensions to obtain the surface scattering model reference matrix: Among them, (x r0 ,y r0 ) is the center coordinate of the surface target, L r is the center length of the surface target, H r is the surface target width, is the surface target angle, and k represents the kth line target.

6. The method according to claim 5, characterized in that The step of obtaining a target scattered echo vector of an array element in a radar array according to a two-dimensional uncorrelated radiation field in time and space, and obtaining an imaging equation of the target according to the target scattered echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix includes: According to the two-dimensional uncorrelated radiation field in time and space, the target scattered echo vector of the array element in the radar array is obtained as follows: S R =[S R (1),S R (2),...,S R (M)] T According to the target scattered echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix, the imaging equation of the target is obtained as follows: S R =S p ·s p +S l ·s l +S r ·s r +n Among them, S p is the point scattering model reference matrix, S l is the reference matrix of the line scattering model, S r is the reference matrix of the surface scattering model, is the point target scattering coefficient of the reference matrix of the point scattering model to be solved, is the line target scattering coefficient of the reference matrix of the line scattering model to be solved, is the surface target scattering coefficient of the reference matrix of the surface scattering model to be solved, and n is Gaussian white noise.

7. The method according to any one of claims 1 to 6, characterized in that: Solving the imaging equation to perform target imaging includes: The imaging equation is transformed to obtain the objective function: Among them, λ p is the regularization coefficient of the point target scattering coefficient of the reference matrix of the point scattering model to be solved, λ l is the regularization coefficient of the line target scattering coefficient of the reference matrix of the line scattering model to be solved, λ r is the regularization parameter of the surface target scattering coefficient of the surface scattering reference matrix to be solved; The target function is solved by using the alternating direction multiplier method to perform target imaging.

8. A microwave wavefront modulation forward imaging device based on an attribute scattering model, characterized in that: The device comprises: An array construction module, used to construct a radar array; the radar array includes a plurality of array elements; a radiation field construction module, configured to obtain a microwave signal emitted by the radar array by performing random frequency hopping modulation on the wavefront of the microwave emitted by the array element, and to construct a spatiotemporal two-dimensional uncorrelated radiation field of a target imaging plane according to the microwave signal; A reference matrix construction module is used to discretize the imaging plane to obtain a discretized grid, obtain a point scattering model reference matrix corresponding to the imaging plane according to the microwave signal and a reference signal of a center point of the discretized grid, and perform one-dimensional integration and two-dimensional integration on the point scattering model reference matrix to obtain a line scattering model reference matrix and a surface scattering model reference matrix; The imaging module is used to obtain the target scattered echo vector of the array element in the radar array according to the two-dimensional uncorrelated radiation field in time and space, obtain the imaging equation of the target according to the target scattered echo vector, the point scattering model reference matrix, the line scattering model reference matrix and the surface scattering model reference matrix, solve the imaging equation, and perform target imaging.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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