A spatially projected focused correlation imaging method and system

Abstract

This invention discloses a spatial projection focusing correlation imaging method and system, comprising: acquiring the results of near-field scanning and calculating the far-field random radiation field using a field transformation algorithm as a reference radiation field; jointly processing the received signal and the reference radiation field based on first-order statistical correlation to obtain the target's azimuth imaging result; performing spatial projection focusing, based on singular value decomposition, spatially projecting and focusing the echo signal to calculate the echo signal in any focusing region; calculating the target's azimuth super-resolution imaging result in any focusing region based on a super-resolution optimization algorithm; and obtaining all target images within the detection region through the organic combination of images from each focusing region. The imaging method of this invention significantly improves the detection performance of the detection system. By using spatial projection focusing, the robustness of super-resolution imaging is improved, and the imaging anti-interference performance is enhanced.

Description

Technical Field

[0001] This invention relates to the field of microwave imaging, and in particular to a spatial projection focusing correlation imaging method and system. Background Technology

[0002] Radar correlation imaging is a novel staring high-resolution imaging technique that draws on the ghost imaging method in optical imaging. It constructs different random detection modes by transmitting signals through a random transmission array or a random modulation metasurface antenna array, thereby simulating a light field distribution with random fluctuations. By utilizing the differences in signal distribution in different directions of the radiation field, super-resolution imaging of the target can be achieved.

[0003] Correlation imaging methods based on random emission arrays construct random radiation fields by randomly modulating the excitation signal, which can form different detection modes in dimensions such as time, frequency, and polarization.

[0004] Super-resolution imaging using correlation imaging involves constructing a detection equation by simultaneously integrating the echo signal and the corresponding reference radiation field. The echo signal is a one-dimensional sequence containing target information but lacking spatial resolution. The reference radiation field, after spatial discretization, forms a two-dimensional matrix containing spatial resolution information but lacking target information. Solving the detection equation using a suitable super-resolution optimization algorithm yields the super-resolution imaging results of the target.

[0005] The existing technology has at least the following problems:

[0006] Solving the detection equation for super-resolution imaging involves a large amount of data, resulting in low imaging efficiency. When the target spatial distribution range is large, the super-resolution imaging method will have low robustness and insufficient anti-interference ability. Furthermore, it requires a high degree of independence and number of detection modes, leading to a complex and costly detection system. Summary of the Invention

[0007] To address the issues of high requirements for the number of detection modes and low robustness and insufficient anti-interference capability leading to decreased super-resolution imaging performance when the target spatial distribution range is large or the background noise is strong, this invention proposes a spatial projection focusing correlation imaging method and system. Through data processing, the echo signal is focused on different coherent regions for super-resolution imaging. While retaining the advantages of imaging system flexibility, simplicity, and low cost, it improves the robustness and anti-interference capability of super-resolution imaging.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a spatial projection focusing correlation imaging method, comprising:

[0010] The results of the near-field scan are obtained, and the random radiation field of the far field is calculated through the field transformation algorithm as a reference radiation field.

[0011] The received signal and the reference radiation field are jointly processed based on first-order statistical correlation to obtain the imaging result of the target in the azimuth direction.

[0012] Spatial projection focusing is performed on the echo signal based on singular value decomposition, and the echo signal in any focusing region is calculated.

[0013] The super-resolution imaging result of the target orientation within any focal region is calculated based on the super-resolution optimization algorithm.

[0014] Images of all targets within the detection area are obtained by organically combining images of each focused region.

[0015] As a further improvement of the present invention, the statistical dimensions of the random radiation field include time, frequency, and polarization; the random radiation field is achieved by randomly modulating the frequency dimension of the transmitted signal using a metasurface array.

[0016] As a further improvement of the present invention, the step of using a test system to perform a near-field scan of the coded radiation field of the random modulation array and calculating the far-field random radiation field using a field transformation algorithm as a reference radiation field includes:

[0017] The near-field distribution of a random modulation array is tested using a test system. The measurement needs to cover frequency and polarization information. The spatial random radiation field distribution with amplitude and phase in the far field is calculated by a near-far field transformation algorithm and used as a reference radiation field, i.e., the detection mode.

[0018] As a further improvement of the present invention, the joint processing of the received signal and the reference radiation field based on first-order statistical correlation to obtain the imaging result of the target in the azimuth direction includes:

[0019] By performing first-order statistical correlation operations on the received signals and detection modes under different detection modes, the azimuth estimation result of the target is initially obtained. Its resolution depends on the antenna aperture and is regarded as a coherent region. Based on this, the imaging region is constrained to the focusing region by projection focusing. A single projection focusing region is generally no larger than a coherent region.

[0020] As a further improvement of the present invention, the preliminary azimuth estimation result of the target, the resolution of which depends on the antenna aperture, is regarded as a coherent region, including:

[0021] The imaging result of the target in the azimuth direction is a preliminary estimate of the overall azimuth imaging of the target. The echo at the receiving end is the echo signal after the random radiation field is reflected by the overall target. Its first-order statistical correlation with the reference signal can obtain target information in different azimuth directions. Moreover, the resolution capability depends on the size of the metasurface array antenna. The resolution unit is a coherent region.

[0022] As a further improvement of the present invention, the spatial projection focusing includes:

[0023] The region to be focused is spatially discretized, and the reference radiation field within the region is calculated to obtain the reference matrix. Singular value decomposition is performed on the reference matrix to obtain a complete orthogonal basis of the linear space constructed by the eigenvectors of the reference matrix. The projection matrix is ​​calculated based on the complete orthogonal basis. The total echo signal is multiplied by the projection matrix to obtain the target echo within the corresponding region. During the projection process, the data dimension remains unchanged, and the energy is concentrated within a specific region.

[0024] As a further improvement of the present invention, the step of calculating the target azimuth super-resolution imaging result within any focal region based on the super-resolution optimization algorithm includes:

[0025] After obtaining the echo signal of the corresponding coherent region, the detection equation is obtained by combining it with the reference matrix. The prior distribution of the target and the prior distribution of the echo noise are set. Then, the sparse Bayesian estimation algorithm is used to solve the detection equation to obtain the super-resolution imaging result of the target. The super-resolution imaging result of the overall target can be obtained by combining the target imaging results of each coherent region.

[0026] As a further improvement of the present invention, the step of obtaining all target images within the detection area through the organic combination of images from each focused region includes:

[0027] The echo signals and reference radiation fields in all focused regions are combined to form a group of detection equations. The super-resolution optimization algorithm is used to solve this group of detection equations to obtain the super-resolution imaging results of the target. The images of all targets in the detection region are obtained by organically combining the images of each focused region.

[0028] As a further improvement of the present invention, the result of obtaining the near-field scan is: obtaining the result of near-field scanning of the coded radiation field of the random modulation array using a test system.

[0029] In a second aspect, the present invention provides a spatial projection focusing correlation imaging system, comprising:

[0030] The acquisition module is used to acquire the results of near-field scanning and to deduce the random radiation field of the far field through a field transformation algorithm, which serves as a reference radiation field.

[0031] The processing module is used to jointly process the received signal and the reference radiation field based on first-order statistical correlation to obtain the imaging result of the target in the azimuth direction.

[0032] The decomposition module is used for spatial projection focusing. Based on singular value decomposition, it performs spatial projection focusing on the echo signal and calculates the echo signal within any focusing region.

[0033] The calculation module is used to calculate the target azimuth super-resolution imaging results within any focal region based on the super-resolution optimization algorithm;

[0034] The combination module is used to obtain images of all targets within the detection area by organically combining images of each focused area.

[0035] Thirdly, the present invention provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the spatial projection focusing correlation imaging method.

[0036] Fourthly, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the spatial projection focusing correlation imaging method.

[0037] Compared with the prior art, the beneficial technical effects of this invention are as follows:

[0038] This invention offers the advantage of low computational complexity. By focusing the echo signal onto different coherent regions, target information within each region is acquired, significantly reducing the data volume of the test matrix and computational complexity in solving the detection equation. It also boasts high anti-interference capability. By reducing the imaging area, the robustness of the super-resolution imaging method is improved, thereby greatly enhancing the system's anti-interference ability. Furthermore, it possesses focused detection capability, allowing focus on the imaging region of interest and extraction of the echo signal from that region from the total target echo, thus enabling the acquisition of fine-grained target information within the focused region. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a spatial projection focusing correlation imaging method according to the present invention;

[0040] Figure 2 This is a flowchart of the present invention;

[0041] Figure 3 This is a simulated target distribution diagram;

[0042] Figure 4 This is a preliminary estimation result of the target orientation based on first-order statistical correlation;

[0043] Figure 5 This represents the super-resolution imaging result within a coherent region after spatial focusing.

[0044] Figure 6 An image of all targets formed through organic combination. Detailed Implementation

[0045] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0046] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0047] like Figure 2 As shown, the first objective of this invention is to provide a spatial projection focusing correlation imaging method, comprising:

[0048] 1) The coded radiation field of the random modulation array is scanned in the near field using the test system, and the random radiation field in the far field is calculated by the field transformation algorithm and used as the reference radiation field.

[0049] 2) The statistical dimensions of random radiation fields include time, frequency, polarization, etc.

[0050] 3) Based on first-order statistical correlation, the received signal and the reference radiation field are jointly processed to obtain the statistical correlation imaging result of the target in the azimuth direction.

[0051] 4) Based on singular value decomposition, spatial projection focusing is performed on the echo signal to calculate the echo signal in any focusing region.

[0052] 5) Calculate the target azimuth super-resolution imaging result within any focal region based on the super-resolution optimization algorithm.

[0053] 6) By organically combining the images of each focused area, images of all targets within the detection area are obtained.

[0054] The principle of this invention is as follows: Near-field testing is performed under a random modulation array transmission system, and a far-field random radiation field is obtained through field transformation as a reference radiation field. Based on first-order statistical correlation, the azimuth direction of the target is initially estimated; the resolution of the azimuth direction depends on the antenna aperture, thereby obtaining target information distributed in several coherent regions along the azimuth direction. Based on singular value decomposition of the reference radiation field, a projection subspace is constructed, and the echo signal in any coherent region is obtained using vector subspace projection, i.e., the echo signal after focusing on a certain spatial projection is extracted from the total target echo signal. Based on a super-resolution optimization algorithm, super-resolution imaging is performed on the target in any focused region, and the images of all targets within the detection region are obtained through the organic combination of images from each focused region. This imaging method significantly improves the detection performance of the detection system. By using spatial projection focusing, the robustness of super-resolution imaging is improved, and the anti-interference performance of imaging is enhanced.

[0055] Among them, such as Figure 1 As shown, the near-field distribution of a random modulation array is tested using a test system. During the measurement, information such as frequency and polarization needs to be covered. The spatial random radiation field distribution with amplitude and phase in the far field is calculated by the near-field transformation algorithm and used as the reference radiation field, i.e., the detection mode.

[0056] As an alternative, the received signals under different detection modes are used to perform first-order statistical correlation operations with the detection modes to obtain the initial azimuth estimation result of the target. Its resolution depends on the antenna aperture and can be regarded as a coherent region. Based on this, the imaging region can be constrained to the focusing region by the projection focusing method. A single projection focusing region is generally no larger than a coherent region.

[0057] The steps involved in spatial projection focusing include:

[0058] The region to be focused is spatially discretized, and the reference radiation field within the region is calculated to obtain the reference matrix. Singular value decomposition is performed on the reference matrix to obtain a complete orthogonal basis of the linear space constructed by the eigenvectors of the reference matrix. The projection matrix is ​​calculated based on the complete orthogonal basis. The target echo within the corresponding region is obtained by multiplying the total echo signal with the projection matrix. During the projection process, the data dimension remains unchanged, and the energy is concentrated within a specific region.

[0059] As an alternative approach, a set of detection equations is constructed by simultaneously combining the echo signals from all focused regions with the reference radiation field. This set of equations is then solved using a super-resolution optimization algorithm to obtain the super-resolution imaging results of the target. Finally, the images of all targets within the detection region are obtained through the organic combination of the images from each focused region.

[0060] The region to be focused is spatially discretized, and the reference radiation field within this region is calculated to obtain a reference matrix. Singular value decomposition is performed on this reference matrix to obtain a complete orthogonal basis for the linear space constructed from the eigenvectors of the reference matrix. The projection matrix is ​​then calculated based on this complete orthogonal basis. Multiplying the total echo signal by the projection matrix yields the target echo within the corresponding coherent region. During projection, the data dimension remains unchanged, and the energy is concentrated within a specific focusing region. After obtaining the echo signal from the corresponding coherent region, a detection equation is obtained by combining it with the reference matrix. Prior distributions of the target and echo noise are set, and a sparse Bayesian estimation algorithm is used to solve this detection equation to obtain the super-resolution imaging result of the target. Combining the target imaging results from each coherent region yields the overall super-resolution imaging result of the target.

[0061] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0062] The basic idea of ​​this invention is to achieve highly robust super-resolution imaging of targets within a coherent region through spatial projection focusing.

[0063] Figure 2 This is a flowchart of a spatial projection focusing microwave correlation imaging method provided in an embodiment of the present invention. This embodiment employs a metasurface array to randomly modulate the transmitted signal in the frequency dimension, i.e., generating low-correlation detection modes at discrete frequency points, as shown in the figure. The method mainly includes the following steps;

[0064] Step a: Use the test system to perform near-field scanning tests on the radiation field of the metasurface array antenna, and deduce the random radiation pattern in the far-field space through field transformation method.

[0065] Step b: Based on first-order statistical correlation, the received signal and the reference radiation field are jointly processed to obtain the imaging result of the target in the azimuth direction.

[0066] Step c: Perform spatial projection focusing. Based on singular value decomposition, perform spatial projection focusing on the echo signal and calculate the echo signal in any focusing region.

[0067] Step d: Combine the reference matrix in the focusing area with the corresponding echo signal to obtain the detection equation, and then use the sparse Bayesian estimation algorithm to obtain the target image in the sub-region.

[0068] In step b, a reference plane with a distance of R0 is set. Different positions on the reference plane can be represented as... The reference signal on the reference plane can then be represented as

[0069]

[0070] in, m represents different detection modes.

[0071] By using the fundamental correlation method to perform azimuth imaging of the target, we can obtain...

[0072]

[0073] Therefore, the azimuth imaging result can be approximately derived as follows:

[0074]

[0075] This result is a preliminary estimate of the overall azimuth imaging of the target. The echo at the receiver is the echo signal after the random radiation field is reflected by the overall target. Its first-order statistical correlation with the reference signal can obtain target information in different azimuth directions. Moreover, the resolution capability depends on the size of the metasurface array antenna, and the resolution unit is a coherent region.

[0076] To perform super-resolution imaging of targets within the coherent region, spatial projection focusing is performed in step c. By confining the echo signal to a certain coherent region, the target is reconstructed using the echo signal within that region and the reference signal. The echo received by the imaging system is the total echo of all targets in the region. The following describes the method of extracting the echo within a certain coherent region from the total echo using azimuth projection.

[0077] The total echo signal is s r If the number of detection modes is M, then s r It can be viewed as an M-dimensional vector. For a certain coherent region, after spatial discretization, the reference vectors can be combined into a reference matrix and represented as follows:

[0078] S = [s ref (θ1)…s ref (θ Q )]

[0079] All reference signal vectors within this coherent region can be considered as a linear space, and the echo of the target within this region is the total echo s. rThe projection into this linear space. Therefore, it is first necessary to obtain a complete orthogonal basis for this linear space. This is obtained by performing SVD decomposition on the reference matrix.

[0080]

[0081] According to the principle of SVD decomposition, A = [u1…u k This forms a complete orthogonal basis for the linear space, where k = min(M, Q). The projection matrix can be expressed as...

[0082] P = A(A H A) -1 A H

[0083] Therefore, the echo in this coherent region can be expressed as

[0084] s′ r =s r •P

[0085] Therefore, the echo signal within a certain coherent region can be extracted from the total echo signal, achieving spatial projection focusing. In step d, the detection equation is constructed as follows:

[0086] s′ r =S•σ+n

[0087] By combining the sparse Bayesian estimation algorithm to solve the detection equation, the super-resolution imaging results of the target can be obtained.

[0088] In this method, the echo of the corresponding coherent region is obtained by spatial projection focusing on the overall imaging area. Due to the reduction of the imaging spatial area, the computational complexity can be reduced, the robustness of the corresponding super-resolution imaging method can be improved, and fine imaging of the target can be achieved.

[0089] Simulation conditions: based on Figure 2 The system flowchart shown uses Figure 1 The system model shown was used for simulation. All parameters in the simulation were set according to the actual application scenario of radar. The random modulation metasurface array antenna is a one-dimensional distribution, equivalent to a one-dimensional distributed metasurface unit with a length of 2m, an imaging distance of 1km, a center frequency of 33GHz-35GHz, and a total of 100 detection modes at different frequency points.

[0090] Simulation content and results: The targets are discrete point targets distributed across two different coherent regions. Within each coherent region, they are distributed across two range cells and two azimuth cells. The azimuth spacing is 1 / 10 of the coherent region length. The extent of any coherent region can be approximated as... Where λ is the wavelength at the center carrier frequency, R is the imaging distance, and D is the aperture of the metasurface antenna.

[0091] Figure 3 The image shows the distribution of the target in the simulation. There are two point groups of targets located in different coherent regions. The imaging results of this scene demonstrate that the imaging method given in this invention can achieve focusing processing of any coherent region, thereby significantly reducing the mutual interference between the two point groups of targets.

[0092] Figure 4 This is a preliminary estimate of the target's azimuth based on first-order statistical correlation. This result is used to illustrate the preliminary position estimation of two point group targets and also characterizes the imaging effect of traditional phased array radar, thereby delineating the imaging focus area.

[0093] Figure 5 This figure shows the super-resolution imaging result within a coherent region after spatial focusing; it is used to illustrate the super-resolution imaging effect of a single point group target after the application of the spatial focusing algorithm.

[0094] Figure 6 This image shows all targets formed through organic combination. It illustrates the imaging effect of the entire detection area obtained by organically stitching together the super-resolution imaging results of different point groups of targets after the projection focusing algorithm.

[0095] A second objective of this invention is to provide a spatial projection focusing correlation imaging system, comprising:

[0096] The acquisition module is used to acquire the results of near-field scanning and to deduce the random radiation field of the far field through a field transformation algorithm, which serves as a reference radiation field.

[0097] The processing module is used to jointly process the received signal and the reference radiation field based on first-order statistical correlation to obtain the imaging result of the target in the azimuth direction.

[0098] The decomposition module is used for spatial projection focusing. Based on singular value decomposition, it performs spatial projection focusing on the echo signal and calculates the echo signal within any focusing region.

[0099] The calculation module is used to calculate the target azimuth super-resolution imaging results within any focal region based on the super-resolution optimization algorithm;

[0100] The combination module is used to obtain images of all targets within the detection area by organically combining images of each focused area.

[0101] A third objective of this invention is to provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the spatial projection focusing correlation imaging method.

[0102] A fourth objective of this invention is to provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the spatial projection focusing correlation imaging method.

[0103] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0104] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0105] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0106] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1The steps of the function specified in one or more boxes.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A spatial projection focusing correlation imaging method, characterized in that, include: The coded radiation field of the random modulation array was scanned in the near field using a test system to obtain the results of the near field scan. The random radiation field in the far field is calculated using a field transformation algorithm and used as a reference radiation field. The received signal and the reference radiation field are jointly processed based on first-order statistical correlation to obtain the imaging result of the target in the azimuth direction; including: By performing first-order statistical correlation operations on the received signals and detection modes under different detection modes, the azimuth estimation result of the target is initially obtained. Its resolution depends on the antenna aperture and is regarded as a coherent region. Based on this, the imaging region is constrained to the focusing region by the projection focusing method. A single projection focusing region is no larger than a coherent region. Spatial projection focusing is performed on the echo signal based on singular value decomposition, and the echo signal in any focusing region is calculated. The super-resolution super-resolution imaging results of the target orientation within any focal region are calculated based on the super-resolution optimization algorithm; including: After obtaining the echo signal of the corresponding coherent region, the detection equation is obtained by combining it with the reference matrix. The prior distribution of the target and the prior distribution of the echo noise are set. Then, the sparse Bayesian estimation algorithm is used to solve the detection equation to obtain the super-resolution imaging result of the target. The super-resolution imaging result of the overall target is obtained by combining the target imaging results of each coherent region. By organically combining the images of each focused region, images of all targets within the detection area are obtained, including: The echo signals from all focused regions and the reference radiation field are combined to form a group of detection equations. The super-resolution optimization algorithm is used to solve this group of detection equations to obtain the super-resolution imaging results of the target. The images of all targets within the detection region are obtained by organically combining the images of each focused region. The spatial projection focusing includes: The region to be focused is spatially discretized, and the reference radiation field within the region is calculated to obtain the reference matrix. Singular value decomposition is performed on the reference matrix to obtain a complete orthogonal basis of the linear space constructed by the eigenvectors of the reference matrix. The projection matrix is ​​calculated based on the complete orthogonal basis. The total echo signal is multiplied by the projection matrix to obtain the target echo within the corresponding region. During the projection process, the data dimension remains unchanged, and the energy is concentrated within the region.

2. The spatial projection focusing correlation imaging method according to claim 1, characterized in that, The statistical dimensions of the random radiation field include time, frequency, and polarization; the random radiation field is achieved by randomly modulating the frequency dimension of the transmitted signal using a metasurface array.

3. The spatial projection focusing correlation imaging method according to claim 1, characterized in that, The process of using a test system to perform a near-field scan of the coded radiation field of a random modulation array and calculating the far-field random radiation field using a field transformation algorithm, which serves as a reference radiation field, includes: The near-field distribution of a random modulation array is tested using a test system. The measurement needs to cover frequency and polarization information. The spatial random radiation field distribution with amplitude and phase in the far field is calculated by a near-far field transformation algorithm and used as a reference radiation field, i.e., the detection mode.

4. The spatial projection focusing correlation imaging method according to claim 1, characterized in that, The preliminary azimuth estimation result of the target, whose resolution depends on the antenna aperture, is considered as a coherent region, including: The imaging result of the target in the azimuth direction is a preliminary estimate of the overall azimuth imaging of the target. The echo at the receiving end is the echo signal after the random radiation field is reflected by the overall target. The first-order statistical correlation between the echo and the reference signal yields target information in different azimuth directions. The resolution capability depends on the size of the metasurface array antenna, and the resolution unit is a coherent region.

5. The spatial projection focusing correlation imaging method according to claim 1, characterized in that, The result of obtaining the near-field scan is: obtaining the result of a near-field scan of the coded radiation field of a random modulation array using a test system.

6. A spatial projection focusing correlation imaging system, used to implement the spatial projection focusing correlation imaging method of claim 1, characterized in that, include: The acquisition module is used to acquire the results of near-field scanning and to deduce the random radiation field of the far field through a field transformation algorithm, which serves as a reference radiation field. The processing module is used to jointly process the received signal and the reference radiation field based on first-order statistical correlation to obtain the imaging result of the target in the azimuth direction. The decomposition module is used for spatial projection focusing. Based on singular value decomposition, it performs spatial projection focusing on the echo signal and calculates the echo signal within any focusing region. The calculation module is used to calculate the target azimuth super-resolution imaging results within any focal region based on the super-resolution optimization algorithm; The combination module is used to obtain images of all targets within the detection area by organically combining images of each focused area.

Images