A single-bit SAR imaging artifact suppression method and device based on spatially variant harmonic point spread function, equipment and medium

Abstract

The application discloses a single-bit SAR imaging artifact suppression method and device based on a spatially variant harmonic point spread function, equipment and a medium. The method comprises the following steps: estimating continuous-to-ground scene energy by using a coarse image generated by single-bit quantization echo; constructing an energy diffusion kernel based on the modulus square of the spatially variant harmonic point spread function of the spatial position; determining harmonic artifact energy of odd-order harmonics based on the energy diffusion kernel and the continuous-to-ground scene energy; and compensating the coarse image by using the harmonic artifact energy. Under the condition of single-bit quantization spaceborne SAR continuous-to-ground imaging, the modulus square of the spatially variant harmonic point spread function is used to construct an energy diffusion kernel, the harmonic artifact energy is predicted based on the continuous-to-ground scene energy and the energy diffusion kernel, the single-bit quantization nonlinear distortion is converted into an imaging domain harmonic PSF energy prediction problem, the existing method cannot adapt to the nonlinear harmonic artifact prediction problem of the continuous scattering scene, and the artifact suppression effect of single-bit SAR imaging is improved.

Description

Technical Field

[0001] This application relates to the field of radar imaging technology, and in particular to a method, apparatus, device and medium for suppressing single-bit SAR imaging artifacts based on spatially variable harmonic point spread function. Background Technology

[0002] Spaceborne SAR (Synthetic Aperture Radar) can acquire high-resolution two-dimensional images of the Earth's surface under all-weather, day-and-night conditions. With the improvement of resolution, the expansion of mapping swathes, and the development of onboard intelligent processing, the raw echo data rate has increased rapidly, placing significant pressure on onboard storage, analog-to-digital converter power consumption control, satellite-to-ground link bandwidth, and ground processing. Therefore, single-bit quantization, which retains only the symbol information of the real and imaginary parts of the complex echo, can effectively reduce the data volume and has become a worthy research direction for low-power, low-bandwidth spaceborne SAR.

[0003] Existing single-bit SAR imaging methods generally rely on scene sparsity and are suitable for point targets or scenes with a small number of strong scatterers. However, real-world SAR scenes are usually continuous scattering scenes where surface targets, linear targets, and strong scattering points coexist. There is coherent superposition between scattering units, making it impossible to simply decompose the nonlinear distortion after single-bit quantization into a linear superposition of artifacts from each point target. Consequently, the prediction of harmonic artifacts caused by single-bit quantization in continuous ground scenes is insufficient, ultimately affecting the quality of SAR images.

[0004] Therefore, the existing technology still needs to be improved and enhanced. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide a method, apparatus, device and medium for suppressing single-bit SAR imaging artifacts based on spatially variable harmonic point spread function, which addresses the shortcomings of the existing technology.

[0006] To address the aforementioned technical problems, the first aspect of this application provides a single-bit SAR imaging artifact suppression method based on a spatially variable harmonic point spread function, wherein the method includes: A coarse image is generated from a single-bit quantized echo using a fundamental wave SAR imaging operator, and the energy of a continuous ground scene is estimated based on the coarse image. For any odd-order harmonic, the continuous ground-to-ground scenario is divided into several scenario blocks; Harmonic echoes are constructed based on the fundamental echo phase of each scene block, and the harmonic echoes are processed using the fundamental SAR imaging operator to obtain the spatially variable harmonic point spread function of each scene block. A spatial harmonic wave point spread function is constructed for each spatial location in the continuous Earth-to-ground scene using the spatial harmonic wave point spread function of all scene blocks; Using the squared modulus of the spatial harmonic point spread function at each spatial location as the energy spread kernel, the harmonic artifact energy of the odd-order harmonics is determined using the continuous Earth scene energy, wherein the spatial harmonic point spread function is a complex impulse response generated using the fundamental wave SAR imaging operator. The coarse image is compensated using the harmonic artifact energy of all odd-order harmonics to obtain a SAR image with suppressed harmonic artifacts.

[0007] The single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function, wherein the determination of the harmonic artifact energy of the odd-order harmonics using the squared modulus of the spatially variable harmonic point spread function at each spatial location as the energy spread kernel and the continuous ground scene energy specifically includes: For each spatial location, an energy diffusion kernel is constructed using the squared modulus of the spatial harmonic point diffusion function of the spatial location, and the scene energy corresponding to the spatial location is read from the continuous Earth scene energy. The scene energy at all spatial locations is convolved with the energy diffusion kernel to obtain the harmonic artifact energy of the odd-order harmonics.

[0008] The single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function, wherein the step of compensating the coarse image using the harmonic artifact energy of all odd-order harmonics to obtain a SAR image after suppressing harmonic artifacts specifically includes: Harmonic artifact energies of all odd-order harmonics are fused to obtain continuous harmonic artifact energies for the Earth scene. A true strong scattering threshold matrix is ​​constructed based on the coarse image, and a harmonic artifact gating weight matrix is ​​constructed based on the true strong scattering threshold matrix and the continuous ground scene harmonic artifact energy. The harmonic complex response of the continuous Earth-view scene is determined using the coarse image and the spatial harmonic point spread function at each spatial location in the continuous Earth-view scene. The coarse image is subjected to complex response cancellation using the harmonic complex response and the harmonic artifact gating weight matrix to obtain a SAR image with suppressed harmonic artifacts.

[0009] The single-bit SAR imaging artifact suppression method based on spatially varying harmonic point spread function, wherein the construction of the harmonic artifact gating weight matrix based on the true strong scattering threshold matrix and the continuous Earth scene harmonic artifact energy specifically includes: A gated suppression matrix is ​​constructed based on the real strong scattering threshold matrix, and the gated suppression matrix is ​​superimposed with the harmonic artifact energy of the continuous Earth scene to obtain a weighted influence matrix; The ratio of the energy of the continuous ground scene harmonic artifacts to the weighted influence matrix is ​​obtained to obtain the harmonic artifact gating weight matrix.

[0010] The single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function, wherein determining the harmonic complex response of the continuous Earth scene using the coarse image and the spatially variable harmonic point spread function of each spatial location in the continuous Earth scene specifically includes: The complex scattering coefficient matrix of the continuous Earth scene is constructed using the coarse image; The complex scattering coefficient matrix is ​​convolved with the spatial harmonic point spread function of each odd order at each spatial location to obtain the complex harmonic response of each odd order. The harmonic complex responses of all odd-order harmonics are fused to obtain the harmonic complex response of the continuous Earth-to-ground scenario.

[0011] The single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function, wherein after performing complex response cancellation on the coarse image using the harmonic complex response and the harmonic artifact gating weight matrix to obtain a SAR image with suppressed harmonic artifacts, the method further includes: An iterative harmonic inverse filter is constructed based on the spatial harmonic point spread function. The SAR image is subjected to iterative harmonic inverse filtering using the iterative harmonic inverse filter. The iterative harmonic inverse filter is expressed as: , , in, Indicates the first The main response to be recovered in the next iteration. Indicates the first The main response to be recovered in the next iteration. Indicates the iterative weights. Indicates the damping coefficient. Represents the parameters of the iterative inverse filter. Represents SAR image, Indicates the first The harmonic diffusion operator in the next iteration Represents the point spread function of a spatially harmonic wave. Indicates the amplitude coefficient. It indicates odd order.

[0012] A second aspect of this application provides a single-bit SAR imaging artifact suppression device based on a spatially variable harmonic point spread function, wherein the device comprises: The coarse image generation module is used to generate a coarse image for a single-bit quantized echo using a fundamental wave SAR imaging operator, and to estimate the energy of a continuous ground scene based on the coarse image. The harmonic energy determination module is used to divide the continuous ground-viewing scene into several scene blocks for any odd-order harmonic; construct harmonic echoes based on the fundamental echo phase of each scene block, and process the harmonic echoes using the fundamental SAR imaging operator to obtain the spatial harmonic point spread function of each scene block; construct a spatial harmonic point spread function for each spatial location in the continuous ground-viewing scene using the spatial harmonic point spread function of all scene blocks; use the squared modulus of the spatial harmonic point spread function at each spatial location as the energy diffusion kernel, and determine the harmonic artifact energy of the odd-order harmonic using the energy of the continuous ground-viewing scene, wherein the spatial harmonic point spread function is a complex impulse response generated using the fundamental SAR imaging operator; The suppression module is used to compensate the coarse image using the harmonic artifact energy of all odd-order harmonics to obtain a SAR image with suppressed harmonic artifacts.

[0013] A third aspect of this application provides a computer-readable storage medium storing one or more programs that can be executed by one or more processors to implement the steps in the single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function as described above.

[0014] A fourth aspect of this application provides a terminal device, which includes: a processor and a memory; The memory stores a computer-readable program that can be executed by the processor; When the processor executes the computer-readable program, it implements the steps in the single-bit SAR imaging artifact suppression method based on the spatially variable harmonic point spread function as described above.

[0015] Beneficial effects: 1. Under the condition of continuous Earth imaging by single-bit quantized spaceborne SAR, this application constructs an energy diffusion kernel based on the modulus square of the spatial harmonic point spread function at each spatial location. Then, based on the continuous Earth scene energy and the energy diffusion kernel, the harmonic artifact energy is predicted, so as to transform the nonlinear distortion of single-bit quantization into the problem of predicting the harmonic PSF energy in the imaging domain. This solves the problem that existing methods cannot adapt to the nonlinear harmonic artifact prediction problem in continuous scattering scenes and improves the artifact suppression effect of single-bit SAR imaging in continuous Earth scenes.

[0016] 2. This application utilizes the harmonic artifact energy of continuous ground scene and coarse image to construct harmonic artifact gating weights, and uses these harmonic artifact gating weights to perform complex response cancellation, so as to avoid the situation where real strong scatterers are darkened when the coarse image is directly low-pass, smoothed or multiplied by weights, thereby further improving the image quality of single-bit SAR imaging in continuous ground scene and ensuring the imaging contrast of strong scattering targets.

[0017] 3. After gating complex response cancellation, this application constructs an iterative harmonic inverse filter to iteratively process the SAR image, which can further suppress residual parallel stripes and offset diffusion artifacts, thereby further improving the image quality of single-bit SAR imaging in continuous ground scenes. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart of a single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function provided in this application embodiment.

[0020] Figure 2 This is a schematic diagram of the spatially varying point spread function of the fundamental, third, and fifth harmonic waves.

[0021] Figure 3 This is a diagram showing the results of harmonic artifact suppression in a continuous ground scene.

[0022] Figure 4 This is a comparison diagram of the distance profile of the strong scattering point.

[0023] Figure 5 This is a comparison chart of quality indicators before and after suppression.

[0024] Figure 6 The figure shows the experimental results for PSF mismatch, harmonic coefficient error, and SNR noise robustness.

[0025] Figure 7 A schematic diagram of a single-bit SAR imaging artifact suppression device based on spatially variable harmonic point spread function provided in this application embodiment.

[0026] Figure 8 A schematic block diagram of the terminal device provided in the embodiments of this application. Detailed Implementation

[0027] This application provides a method, apparatus, device, and medium for suppressing artifacts in single-bit SAR imaging based on spatially variable harmonic point spread functions. To make the objectives, technical solutions, and effects of this application clearer and more explicit, the following detailed description, with reference to the accompanying drawings and embodiments, further illustrates this application. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0028] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or wireless coupling. The term “and / or” as used herein includes all or any units and all combinations of one or more associated listed items.

[0029] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0030] It should be understood that the sequence number and size of each step in this embodiment do not imply the order of execution. The execution order of each process is determined by its function and internal logic, and should not constitute any limitation on the implementation process of this application embodiment.

[0031] Research has shown that spaceborne SAR (Synthetic Aperture Radar) can acquire high-resolution two-dimensional images of the Earth's surface under all-weather, day-and-night conditions. With the improvement of resolution, the expansion of mapping swathes, and the development of onboard intelligent processing, the raw echo data rate has increased rapidly, placing significant pressure on onboard storage, analog-to-digital converter power consumption control, satellite-to-ground link bandwidth, and ground processing. Therefore, single-bit quantization, which retains only the symbol information of the real and imaginary parts of the complex echo, can effectively reduce the data volume and has become a worthy research direction for low-power, low-bandwidth spaceborne SAR.

[0032] Existing single-bit SAR imaging methods (such as SAR reconstruction methods based on one-bit compressed sensing (CS), low-bit quantization methods based on time-varying or jitter thresholds, single-bit harmonic distortion analysis methods for point targets, and traditional SAR point spread function (PSF) analysis methods) generally rely on scene sparsity and are suitable for scenes with point targets or a small number of strong scatterers. However, real-world SAR scenes are usually continuous scattering scenes with surface targets, linear targets, and strong scattering points coexisting. There is coherent superposition between scattering units, making it impossible to simply decompose the nonlinear distortion after single-bit quantization into a linear superposition of artifacts from each point target. Consequently, the prediction of harmonic artifacts caused by single-bit quantization in continuous ground scenes is insufficient, ultimately affecting the quality of SAR images.

[0033] To address the aforementioned issues, in this embodiment, a coarse image is generated for single-bit quantized echoes using a fundamental-wave SAR imaging operator, and the energy of a continuous ground-to-surface scene is estimated based on the coarse image. For any odd-order harmonic, the spatially variable harmonic point spread function (SVM) at each spatial location in the continuous ground-to-surface scene is obtained, and an energy spread kernel is constructed based on the squared modulus of the SVM at each spatial location. The harmonic artifact energy of the odd-order harmonic is determined based on the energy spread kernel at each spatial location and the energy of the continuous ground-to-surface scene. The coarse image is compensated using the harmonic artifact energies of all odd-order harmonics to obtain a SAR image with suppressed harmonic artifacts. In this application embodiment, under the condition of continuous Earth imaging by single-bit quantized spaceborne SAR, an energy diffusion kernel is constructed based on the modulus square of the spatially varying harmonic point spread function at each spatial location. Then, the harmonic artifact energy is predicted based on the continuous Earth scene energy and the energy diffusion kernel, so as to transform the single-bit quantized nonlinear distortion into the problem of imaging domain harmonic PSF energy prediction. This solves the problem that existing methods cannot adapt to the nonlinear harmonic artifact prediction problem in continuous scattering scenes, and improves the artifact suppression effect of single-bit SAR imaging in continuous Earth scenes.

[0034] It should be noted that the execution entity of each embodiment of this application can be a computing service system with data processing, network communication, and program execution functions, such as an electronic system capable of realizing the above functions, a single-bit SAR imaging artifact suppression system based on spatially variable harmonic point spread function, etc. The following uses the single-bit SAR imaging artifact suppression system based on spatially variable harmonic point spread function (hereinafter referred to as "the system") as an example to describe the following embodiments.

[0035] The application content will be further explained below with reference to the accompanying drawings and the description of the embodiments.

[0036] This embodiment provides a single-bit SAR imaging artifact suppression method based on the spatially variable harmonic point spread function. This method can be applied to spaceborne SAR, airborne SAR, UAV SAR, low-bit ISAR, and other radar imaging systems that employ linear frequency modulation and have single-bit hard limiting processing. Figure 1 As shown, the single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function specifically includes: S10. Generate a coarse image for the single-bit quantized echo using the fundamental wave SAR imaging operator, and estimate the energy of the continuous ground scene based on the coarse image.

[0037] Specifically, a single-bit quantized echo is an echo signal obtained by performing single-bit quantization on the original SAR echo signal. Single-bit quantization reduces the amount of echo data by retaining only the symbol information of the real and imaginary parts of the original SAR echo signal. After obtaining the single-bit quantized echo, the fundamental wave SAR imaging operator can be directly used to image the single-bit quantized echo to obtain a single-bit SAR coarse image.

[0038] The fundamental wave SAR imaging operator can be a traditional fundamental wave SAR imaging operator. For example, taking range Doppler processing as an example, the fundamental wave SAR imaging operator can be represented as a concatenation of the range compression operator, the range migration correction operator, and the azimuth compression operator, that is, the fundamental wave SAR imaging operator can be: , in, This represents the two-dimensional echo data or intermediate echo matrix input to the fundamental wave SAR imaging operator. This represents the fundamental wave SAR imaging operator. This indicates a distance compression operator designed based on the fundamental frequency range. This represents an azimuth compression operator designed based on the fundamental azimuth Doppler modulation frequency; This represents the distance migration correction operator. If implemented in the frequency domain, For distance to Fourier transform Fundamental range matched filter Composed of distance to inverse Fourier transform; For the Fourier transform from orientation Fundamental azimuth matched filter It consists of the inverse Fourier transform of the orientation direction.

[0039] Furthermore, since the coarse image contains the initial scattering distribution of the continuous ground scene, the energy of the continuous ground scene can be estimated from the coarse image, where the energy of the continuous ground scene can be expressed as: , in, This represents the energy of a continuous Earth-based scenario. Indicates a coarse image. This indicates normalization processing. This represents the coarse imaging energy enhancement factor, which can be preset according to the actual imaging scenario, such as... The range of values ​​is , .

[0040] S20. For any odd-order harmonic, obtain the spatial harmonic point spread function at each spatial location in the continuous Earth-to-ground scene, and use the squared modulus of the spatial harmonic point spread function at each spatial location as the energy spread kernel, and use the energy of the continuous Earth-to-ground scene to determine the harmonic artifact energy of the odd-order harmonic.

[0041] Specifically, when performing single-bit quantization on the original SAR echo signal (i.e., the unquantized complex echo signal), each sampled element in the original SAR echo signal is processed as follows: , in, This represents the original SAR echo signal. This represents a time scalar representing distance. Indicates a slow time scalar for location. Indicates a single-bit quantized echo. Represents a symbolic function. This represents the operation of taking the real part of a complex number. This represents the operation of taking the imaginary part of a complex number. It represents the imaginary unit.

[0042] For the cosine-type components of the real part, the hard-limiting function has a Fourier series expansion: , in, Represents the cosine component of the real part.

[0043] Correspondingly, a single-bit quantized echo can be viewed as the superposition of the fundamental term and odd harmonic terms such as the third and fifth orders. This single-bit quantized echo can be expressed as: , in, Indicates the fundamental echo phase history. Indicates odd order, This represents the harmonic coefficient.

[0044] As can be seen from the approximate representation of the single-bit quantized echo, single-bit quantization not only leads to the loss of amplitude information, but also introduces [other problems]. This represents the odd-order harmonic echo. For the fundamental-wave SAR imaging operator, if the input is a fundamental-wave term, the imaging result is an ideal reference image. If the input to the fundamental wave SAR imaging operator is a harmonic echo, since the fundamental wave SAR imaging operator is constructed according to the fundamental wave phase, and the harmonic echo cannot be correctly focused on the true position, it will form a shift, stretching, broadening, multi-peak or striped response.

[0045] Based on this, in the embodiments of this application, the unit point target will be processed through the first... The complex impulse response after the first harmonic echo and fundamental wave SAR imaging operator is expressed as a spatially harmonic point spread function, which can be expressed as: , in, Indicates spatial location Spatial harmonic point spread function, This represents the fundamental wave SAR imaging operator. This represents the fundamental echo phase history of a unit point target. It represents the imaginary unit.

[0046] It is understood that, in this embodiment, a spatial harmonic point spread function (SPDF) for odd-order harmonics is constructed. This SPDF describes the artifact diffusion pattern generated by the single-bit quantization nonlinear term in the imaging domain. Specifically, for any odd-order harmonic, each spatial location in a continuous ground-to-surface scene corresponds to a SPDF, which represents the spatial location. The odd-order harmonics are used to generate a complex impulse response through the fundamental-wave SAR imaging operator. This complex impulse response includes the offset, defocus, broadening, sidelobes, and fringe structures formed by the harmonic terms under fundamental-wave matching conditions.

[0047] In one embodiment, obtaining the spatial harmonic point spread function at each spatial location in the continuous Earth-view scenario specifically includes: The continuous ground-viewing scenario is divided into several scenario blocks; For each scene block, a harmonic echo is constructed based on the fundamental echo phase of the scene block, and the harmonic echo is processed using the fundamental SAR imaging operator to obtain the spatially variable harmonic point spread function of the scene block. Spatial harmonic point spread functions are constructed for each spatial location in the continuous Earth-to-ground scenario using spatial harmonic point spread functions for all scene blocks.

[0048] Specifically, a continuous Earth-viewing scene is a large imaging area. The distance migration characteristics and Doppler modulation frequencies differ at different locations within the continuous Earth-viewing scene, thus the shape and location of the harmonic response also vary with spatial location. Scene segmentation involves dividing the continuous Earth-viewing scene into non-overlapping scene blocks according to a spatial grid. The range of each scene block can be determined based on orbital parameters and imaging geometry, ensuring that the phase change error within the block meets the imaging focusing requirements.

[0049] For each scene block, the unit target point of that scene block is The corresponding original SAR echo signal (unquantized fundamental echo) can be expressed as: , in, Indicates the unit target point The original SAR echo signal, Indicates the unit target point The fundamental echo phase history.

[0050] The first bit generated by single-bit hard limiting The first harmonic echo can be represented as: , in, Indicates the unit target point The Harmonic echo.

[0051] Then, the fundamental wave SAR imaging operator is used to apply the first... Imaging the first harmonic echoes yields the spatial harmonic point spread function for each scene block. This harmonic point spread function is expressed as: , in, The harmonic point spread function represents the scene segmentation. This represents the fundamental wave SAR imaging operator.

[0052] Finally, considering that the range and azimuth parameters may vary with the scene location during wide-swath or high-angle-view imaging with spaceborne SAR, the artifact shapes produced by the same harmonic at different range-azimuth locations may differ. Therefore, the harmonic point spread function can be expressed as a spatially location-dependent spatially variable harmonic point spread function, which is expressed as: , in, The spatial harmonic point spread function represents the scene segmentation. This indicates that when a unit point target is placed at the center of this scene block, the unit point target is at a distance of [time value missing]. and direction slow time The fundamental echo phase history, This represents the fundamental wave SAR imaging operator.

[0053] It is understandable that the spatial harmonic wave point spread function It's not an experience template, but rather the first unit point target. The image domain complex response (i.e., complex impulse response) obtained after imaging processing by the fundamental wave SAR imaging operator inputting the harmonic echo contains the offset, defocus, broadening, sidelobe and fringe structures formed by the harmonic echo under fundamental wave matching conditions.

[0054] For example, taking range-oriented linear frequency modulated echo as an example, if the fundamental range phase of a unit point target is approximately... , then the first The first harmonic distance phase is: , in, Indicates the first First harmonic distance phase, This indicates the center delay corresponding to a unit point target. This indicates the distance-directed linear frequency modulation.

[0055] However, conventional range compression filters are still constructed based on the fundamental frequency modulation, i.e., fundamental range compression matched filters. correspond The range-matched filtering output of the fundamental range compression matched filter can be expressed as: , in, This represents the range-matched filtering output of the fundamental range compression matched filter. Let represent the independent variable of the one-dimensional integral.

[0056] when When, the second phase can be correctly matched and compressed into a spike; when When the number is odd, the integral contains a residue. The corresponding second-order phase mismatch will not result in an ideal spike, but will instead manifest as range broadening, sidelobe enhancement, or shift. Similarly, in the azimuth direction, if the harmonic azimuth phase is inconsistent with the fundamental azimuth matching filter, it will cause azimuth defocus, shift, or fringes.

[0057] Furthermore, after obtaining the spatial harmonic diffusion function (SHDF) for each scene block, a SHDF library can be constructed based on the SHDFs of all scene blocks. This library can then be used to determine the SHDF for each spatial location within a continuous ground scene. Specifically, for any spatial location (which could be a single pixel or the center pixel of an image block, etc.), the SHDF for the scene block corresponding to that location can be directly used as the SHDF for that location; alternatively, several neighboring scene blocks can be obtained, and the SHDF for that scene block can be used in conjunction with spatial interpolation to obtain the SHDF for that location; or, several neighboring scene blocks can be selected based on distance, and the SHDF for that location can be obtained through spatial interpolation, etc.

[0058] It should be noted that, in engineering implementation, to reduce computational load, a spatial harmonic point spread function (SHS-PFS) library can be pre-built offline or during the first imaging phase. Then, during real-time operation, this library can be directly used to obtain the SHS-PFS function for each spatial location. Furthermore, when using the SHS-PFS library, spatial changes can be monitored. When the monitored spatial changes meet preset requirements, the scene blocks can be refined, or spatial interpolation can be used to determine the corresponding SHS-PFS function for each spatial location. When the monitored spatial changes do not meet the preset requirements, the SHS-PFS function corresponding to the scene block can be directly used as the SHS-PFS function for the spatial location.

[0059] The embodiments of this application adapt to changes in spatial parameters in large-scale imaging scenes by processing in blocks. This ensures the accuracy of the harmonic point spread function in describing spatial variation characteristics, while avoiding the problem of a surge in computation caused by calculating the point spread function separately for each spatial location.

[0060] Furthermore, in step S20 above, since the single-bit quantization in the continuous ground scenario satisfies: ,in, This represents the weight distribution function over a two-dimensional domain. The two independent variables represent the two-dimensional integral domain, thus making it impossible to simply decompose a continuous Earth scene into a large number of point targets and predict the location of pseudo-targets point by point. To address this, embodiments of this application utilize the spatially variable harmonic point spread function and the continuous Earth scene energy to predict the harmonic artifact energy of odd-order harmonics. This harmonic artifact energy is used to reflect the intensity of harmonic diffusion contamination at each spatial location.

[0061] In one embodiment, determining the harmonic artifact energy of the odd-order harmonics using the squared modulus of the spatially varying harmonic point spread function at each spatial location as the energy spread kernel and the continuous Earth-based scene energy specifically includes: For each spatial location, an energy diffusion kernel is constructed using the squared modulus of the spatial harmonic point diffusion function of the spatial location, and the scene energy corresponding to the spatial location is read from the continuous Earth scene energy. The scene energy at all spatial locations is convolved with the energy diffusion kernel to obtain the harmonic artifact energy of the odd-order harmonics.

[0062] Specifically, no. The complex pseudo-effect of the first harmonic can be approximated as follows: , in, Indicates the first The complex pseudo-effect of first harmonics should be considered. This represents the amplitude coefficient.

[0063] After discretizing the continuous Earth-view scene into several scattering units, the first... The complex pseudo-effect of the first harmonic should be expressed as the superposition of the responses of each scattering unit, the third harmonic... The expected energy of the complex pseudo-effect of the first harmonic is expressed as: , in, Indicates the first Each scattering unit is diffused by the spatial harmonic point diffusion function The image domain response diffused to the current pixel. express The complex conjugate, Indicates the first Each scattering unit is diffused by the spatial harmonic point diffusion function The image domain response diffused to the current pixel. Indicates the first The amplitude coefficient of each scattering unit Indicates the first The complex conjugate, Indicates the first The amplitude coefficient of each scattering unit Indicates the first The energy of the complex pseudo-influence of the first harmonic.

[0064] Furthermore, for continuous surface scattering, if the complex scattering phases of different scattering units are weakly correlated, or if the cross term is weakened after multi-look averaging or local averaging, then there will be .So, The expectation approaches zero. Therefore, the first... The energy expectation of the complex pseudo-effect of the first harmonic can be approximated as: .

[0065] Based on this, after obtaining the energy of the continuous Earth-to-ground scene, the amplitude coefficient of the continuous Earth-to-ground scene is constructed using the energy. The squared modulus of the spatial harmonic point spread function at each spatial location is used as the energy spread kernel, and convolution operation is used to predict the first... The harmonic artifact energy of the first harmonic. Among them, the first harmonic... The harmonic artifact energy of a first harmonic can be expressed as: , in, Indicates the first Harmonic artifact energy of first harmonics, This represents the energy of a continuous Earth-based scenario. This represents the spatial harmonic point spread function.

[0066] It is understood that the embodiments of this application use continuous-path scene energy and spatially varying harmonic point spread function to predict harmonic artifact energy, rather than the harmonic complex response itself. Furthermore, when predicting harmonic artifact energy, the following methods are utilized: As an energy diffusion nucleus, rather than using and As an energy diffusion nucleus. If directly used In energy risk prediction, complex phases can cause mutual cancellation or enhancement between different scattering units, making the prediction results extremely sensitive to random phases. Energy risk prediction is performed so that the predicted harmonic artifact energy represents the intensity of harmonic diffusion pollution at a spatial location, and it is more consistent with the statistical energy of continuous surface scattering. This is a feature of the embodiments in this application compared to existing general methods. The key difference between deconvolution and point target artifact prediction.

[0067] In layman's terms, It describes what the harmonic artifacts of a single point target look like, while This describes where the harmonic artifacts of the unit point target distribute energy; It is the result of superimposing the harmonic complex responses of many scattering units in the entire continuous Earth scene. The continuous Earth scene is composed of a large number of scattering units, and the phase of a single scattering unit is difficult to determine accurately, but the energy of the continuous Earth scene can be estimated from the coarse image. Therefore, the embodiments of this application do not guess the artifact position of each unit point target, but predict where on the entire coarse image is more susceptible to harmonic contamination.

[0068] S30. The coarse image is compensated using the harmonic artifact energy of all odd-order harmonics to obtain a SAR image after suppressing harmonic artifacts.

[0069] Specifically, after obtaining the harmonic artifact energies of all odd-order harmonics, the harmonic artifact energies of all odd-order harmonics can be superimposed to obtain continuous harmonic artifact energy for the Earth scene. This continuous harmonic artifact energy can then be used to compensate for the coarse image. For example, the continuous harmonic artifact energy for the Earth scene can be directly subtracted from the coarse image to obtain a final SAR image with suppressed harmonic artifacts; alternatively, an energy compensation mask can be constructed based on the continuous harmonic artifact energy for the Earth scene, and the energy compensation mask and the coarse image can be weighted pixel by pixel to reduce the imaging weight of areas with high artifact energy, thereby suppressing harmonic artifacts.

[0070] In one embodiment, the step of compensating the coarse image using the harmonic artifact energy of all odd-order harmonics to obtain a SAR image with suppressed harmonic artifacts specifically includes: Harmonic artifact energies of all odd-order harmonics are fused to obtain continuous harmonic artifact energies for the Earth scene. A true strong scattering threshold matrix is ​​constructed based on the coarse image, and a harmonic artifact gating weight matrix is ​​constructed based on the true strong scattering threshold matrix and the continuous ground scene harmonic artifact energy. The harmonic complex response of the continuous Earth-view scene is determined using the coarse image and the spatial harmonic point spread function at each spatial location in the continuous Earth-view scene. The coarse image is subjected to complex response cancellation using the harmonic complex response and the harmonic artifact gating weight matrix to obtain a SAR image with suppressed harmonic artifacts.

[0071] Specifically, the harmonic artifact energy of a continuous ground scene is determined by the harmonic artifact energy of all odd-order harmonics, and can be expressed as: , in, This represents the energy of harmonic artifacts in a continuous Earth scene. Indicates the first Harmonic artifact energy of first harmonics, Indicates the first The harmonic artifact energy weights of the first harmonic can be determined based on the harmonic coefficients or by methods such as offline calibration of single-bit simulation of a unit point target.

[0072] Furthermore, after obtaining the continuous harmonic artifact energy of the Earth scene, a true strong scattering threshold matrix can be constructed based on the coarse image. This true strong scattering threshold matrix can be expressed as: , in, Represents the true strong scattering threshold matrix. Represents a coarse image. This indicates normalization processing.

[0073] Then, a harmonic artifact gating weight matrix is ​​constructed based on the true strong scattering threshold matrix and the harmonic artifact energy of the continuous Earth scene. This harmonic artifact gating weight matrix is ​​positively correlated with the harmonic artifact energy of the continuous Earth scene and negatively correlated with the true strong scattering threshold matrix. This allows the harmonic artifact gating weight matrix to assign higher weights to regions with high artifact energy and low true scattering intensity, and lower weights to regions with low artifact energy and high true scattering intensity, thereby achieving more accurate artifact suppression.

[0074] In one embodiment, constructing the harmonic artifact gating weight matrix based on the true strong scattering threshold matrix and the continuous Earth-to-ground scene harmonic artifact energy specifically includes: A gated suppression matrix is ​​constructed based on the real strong scattering threshold matrix, and the gated suppression matrix is ​​superimposed with the harmonic artifact energy of the continuous Earth scene to obtain a weighted influence matrix; The ratio of the energy of the continuous ground scene harmonic artifacts to the weighted influence matrix is ​​obtained to obtain the harmonic artifact gating weight matrix.

[0075] Specifically, when constructing the harmonic artifact gating weight matrix, the true strong scattering threshold matrix is ​​introduced as a suppression term into the harmonic artifact gating weight matrix. This protects the true strong scatterers during the compensation process for coarse images, preventing them from being darkened. The harmonic artifact gating weight matrix can be expressed as: , in, This represents the harmonic artifact gating weight matrix. Represents the true strong scattering threshold matrix. This represents the energy of harmonic artifacts in a continuous Earth scene. Represents the protection factor of a real strong scatterer, such as The range of values ​​is wait, Represents the smoothing constant, such as The range of values ​​is wait.

[0076] It should be noted that in practical applications, other methods can also be used to determine the harmonic artifact gating weight matrix, such as using exponential, piecewise threshold, or strong scattering protection factors.

[0077] From the expression of the harmonic artifact gating weight matrix, it can be seen that when Larger and When smaller, The larger the value, the more likely the location is to be a harmonic artifact region. When it is large, Received Suppression is used to protect real strong scatterers.

[0078] Furthermore, in acquiring Then, the harmonic complex response of the continuous Earth-based scene can be calculated using the coarse image and the spatially varying harmonic point spread function at each spatial location in the continuous Earth-based scene. The harmonic artifact component is determined by the harmonic complex response, and then subtracted from the coarse image to complete the complex response cancellation, outputting the final SAR image after suppressing harmonic artifacts. Based on this, the determination of the harmonic complex response of the continuous Earth-view scene using the coarse image and the spatially varying harmonic point spread function of each spatial location in the continuous Earth-view scene specifically includes: The complex scattering coefficient matrix of the continuous Earth scene is constructed using the coarse image; The complex scattering coefficient matrix is ​​convolved with the spatial harmonic point spread function of each odd order at each spatial location to obtain the complex harmonic response of each odd order. The harmonic complex responses of all odd-order harmonics are fused to obtain the harmonic complex response of the continuous Earth-to-ground scenario.

[0079] Specifically, the complex scattering coefficient matrix represents the scattering information of each scattering unit in a continuous Earth-to-ground scene and can be directly obtained from a coarse image. Since the amplitude and phase of the coarse image contain the scattering information of the scattering units, the complex scattering coefficient matrix of the continuous Earth-to-ground scene can be constructed using the amplitude and phase of the coarse image. This complex scattering coefficient matrix can be expressed as: , in, Represents the complex scattering coefficient matrix. Represents a coarse image. This represents the maximum value function.

[0080] After obtaining the complex scattering coefficient matrix, the matrix is ​​convolved with the spatially varying harmonic point spread function corresponding to each odd-order spatial location to obtain the corresponding order of harmonic complex response. Then, all odd-order harmonic complex responses are weighted and fused according to the harmonic coefficients to obtain the complete continuous Earth-based scene harmonic complex response. The continuous Earth-based scene harmonic complex response can be expressed as: , in, This represents the harmonic complex response of a continuous scene to the ground. This represents the amplitude coefficient.

[0081] Finally, the harmonic artifact component is determined based on the harmonic artifact gating weight matrix and the continuous harmonic complex response of the Earth scene. This harmonic artifact component is then subtracted from the coarse image to obtain a SAR image that suppresses harmonic artifacts while retaining true strong scattering information. The SAR image after suppressing harmonic artifacts can be represented as: , in, This represents the SAR image after suppressing harmonic artifacts. This represents the adjustment coefficient.

[0082] This application embodiment achieves a balance between artifact suppression and real scattering protection through gating weights. It effectively reduces harmonic artifact interference in continuous ground-viewing scenarios, improves the contrast and detail clarity of SAR images, and avoids the problem of traditional compensation methods easily damaging real strong scattering targets. It is suitable for continuous ground-viewing SAR imaging scenarios in strip imaging mode and can obtain a more stable and reliable harmonic artifact suppression effect.

[0083] It should be noted that, for those skilled in the art, the embodiments of this application can add or delete steps according to actual needs. The above embodiments only describe the case of odd-order harmonic artifact processing. Those skilled in the art can extend this method to the suppression of even-order harmonic artifacts according to the actual characteristics of the harmonic generation of the imaging system, which will not be elaborated here.

[0084] In one embodiment, the gated complex response cancellation described above can achieve a balance between artifact suppression and protection against true scattering. However, the resulting SAR image after suppressing harmonic artifacts may still contain parallel stripes and offset diffusion artifacts. Therefore, in this embodiment, after obtaining the SAR image after suppressing harmonic artifacts, inverse harmonic filtering can be performed on the SAR image to further eliminate residual harmonic interference.

[0085] Based on this, after performing complex response cancellation on the coarse image using the harmonic complex response and the harmonic artifact gating weight matrix to obtain a SAR image with suppressed harmonic artifacts, the method further includes: An iterative harmonic inverse filter is constructed based on the spatial harmonic point spread function. The SAR image is subjected to iterative harmonic inverse filtering using the iterative harmonic inverse filter. Specifically, the iterative harmonic inverse filter is constructed with the spatially variable harmonic point spread function as a constraint. It is used to further remove residual harmonic artifacts after compensation. In each iteration, the artifact estimate is updated based on the residual harmonic characteristics of the current SAR image, and the updated artifact components are gradually subtracted from the image until the number of iterations reaches a preset threshold (the value of which can be within a certain range). If the residual artifact energy falls below a preset stop threshold, the iterative output of the final SAR imaging result is stopped. This embodiment of the application, through secondary processing using iterative harmonic inverse filtering, can further suppress residual parallel stripes and offset diffusion artifacts, thereby improving the image quality of SAR imaging.

[0086] The iterative harmonic inverse filter is expressed as: , , in, Indicates the first The main response to be recovered in the next iteration. Indicates the first The main response to be recovered in the next iteration. Indicates the iterative weights. Indicates the damping coefficient. The range of values ​​is wait, Represents the parameters of the iterative inverse filter. The range of values ​​is wait, Indicates a coarse image. Indicates the first The harmonic diffusion operator in the next iteration Represents the point spread function of a spatially harmonic wave. This represents the amplitude coefficient. It can be taken as [value] when the simulation model is accurate. =1 achieves global harmonic inverse filtering; in actual data, it can be taken as... =0.35+0.65W and other soft gating methods are used to balance artifact suppression and protection of real strong scatterers.

[0087] To demonstrate the effectiveness of the embodiments of this application, a specific embodiment is provided here. In this specific embodiment, MATLAB is used for image domain equivalent simulation. The system parameters are set as follows: carrier frequency 9.6GHz, bandwidth 150MHz, pulse width 20μs, range modulation frequency 7.5×10^12Hz / s, pulse repetition frequency 2200Hz, center slant distance 720km, and both range and azimuth pixel counts are 256.

[0088] Constructing a continuous Earth-viewing scenario The scene includes random surface scattering, two consecutive ground feature patches, two linear scatterers, and three strong scattering points. To enhance the visualization of harmonic artifacts, the scene phase uses a slowly varying phase superimposed with a small amount of random phase.

[0089] First, generate as follows Figure 2 The spatially variable spread function of the fundamental wave is shown. Third-order spatial harmonic point spread function and the fifth-order spatial harmonic point spread function ,in, , relatively It features offset and phase distortion, and is used to equivalently simulate the offset artifacts and fringe responses formed after fundamental wave matching imaging of single-bit quantized odd harmonics.

[0090] Then, according to Generate a harmonic-free reference image, based on Harmonic artifact complex response terms are generated and noise is superimposed to obtain a conventional single-bit coarse image. Energy risk maps are used during fusion. , As the energy weight of the corresponding order.

[0091] Finally, the continuous scene energy is estimated, the third and fifth harmonic artifact energies are calculated and fused to obtain the continuous scene harmonic artifact energy, the harmonic artifact gating weight matrix constructed using the continuous scene harmonic artifact energy and the continuous scene energy is used for complex response cancellation, and the iterative inverse harmonic filter is used for iterative filtering to output the suppressed SAR image.

[0092] The suppression result of the SAR image after iterative filtering of the continuous ground scene is as follows: Figure 3 As shown, by Figure 3 It can be seen that the energy of harmonic artifacts in the continuous Earth scene can cover the main artifact region, and the harmonic diffusion fringes and residual energy are significantly reduced after iterative filtering. Furthermore, this application's embodiments also compare the strong scattering point range profiles of conventional single-bit coarse imaging, the output of this method, and a harmonic-free reference profile under ideal simulation conditions. The comparison results are as follows: Figure 4 As shown. By Figure 4 It can be seen that the output profile of this method is close to the harmonic-free reference profile.

[0093] Under ideal simulation conditions where the harmonic generation and suppression models are completely consistent, the quality indicators of a single equivalent simulation output are as follows: Normalized root mean square error (NRMSE) decreases from 0.5138 to 0.0197, correlation coefficient increases from 0.9425 to 0.9994, image entropy decreases from 6.2058 to 5.5686, artifact energy ratio decreases from 0.4298 to 0.0007, and the selected cancellation step size... The value is 1.00, and the number of iterations is 8. The above single result is used to illustrate the upper limit that this method can reach in model matching, and does not mean that it will necessarily achieve complete recovery under actual engineering conditions.

[0094] To reduce the randomness introduced by single-run random phase and noise implementations, ten Monte Carlo rapid validations were performed. Each iteration randomly updated the phase perturbation and noise implementation for the continuous scene, and the implementation selected from the main experiment was used. Restore the iteration count. For example... Figure 5 As shown, the mean of 10 Monte Carlo iterations indicates that the normalized root mean square error (NRMSE) decreased from approximately 0.5138 to 0.0197, the artifact ratio decreased from approximately 0.4297 to 0.0007, and the 1-correlation coefficient decreased from approximately 0.0575 to 0.0006. For formal engineering statistical validation, the number of iterations can be increased from 10 to 100, and the mean, standard deviation, or confidence interval should be reported.

[0095] It should be noted that the residual plot uses a uniform reference amplitude display, i.e., a harmonic-free reference image. maximum amplitude Instead of normalizing each residual map separately, it serves as a common dB reference for the residuals before and after suppression. This avoids the misjudgment that the residual energy has been significantly reduced after suppression but is brightened again due to single-map normalization.

[0096] Under actual engineering conditions, due to factors such as track errors, Doppler center deviation, distance migration correction residuals, spatial variable slant range, harmonic coefficient estimation errors, quantization threshold drift, IQ imbalance, automatic gain control fluctuations, and noise disturbances, the harmonic generation model and the suppression model are usually not completely consistent. Therefore, the recovery effect will be lower than the ideal result mentioned above. To avoid the simulation closed-loop leading to overly ideal results, this embodiment also adds a model mismatch robustness sweep experiment. The experimental results are as follows: Figure 6 As shown. By Figure 6 It can be seen that when the PSF parameter mismatch is 10%, 20%, and 30%, the NRMSE after suppression is approximately 0.1669, 0.2034, and 0.2202, respectively, still lower than the pre-suppression NRMSE of 0.5138. When the harmonic coefficient has an error of ±20%, the NRMSE after suppression is approximately 0.0402 to 0.0489. Under the conditions of SNR of 10dB, 20dB, and 30dB, the NRMSE decreases from 0.6806, 0.5221, and 0.5204 to 0.3892, 0.1231, and 0.0418, respectively. The above robustness experiments are single-scan results, used to demonstrate that there is still an improvement trend under model mismatch.

[0097] Based on the above-mentioned single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function, this embodiment provides a single-bit SAR imaging artifact suppression device based on spatially variable harmonic point spread function, such as... Figure 7 As shown, the device includes: The coarse image generation module 100 is used to generate a coarse image for a single-bit quantized echo using a fundamental wave SAR imaging operator, and to estimate the energy of a continuous ground scene based on the coarse image. The harmonic energy determination module 200 is used to divide the continuous ground-viewing scene into several scene blocks for any odd-order harmonic; construct harmonic echoes based on the fundamental echo phase of each scene block, and process the harmonic echoes using the fundamental SAR imaging operator to obtain the spatial harmonic point spread function of each scene block; construct a spatial harmonic point spread function for each spatial location in the continuous ground-viewing scene using the spatial harmonic point spread function of all scene blocks; use the squared modulus of the spatial harmonic point spread function at each spatial location as the energy diffusion kernel, and determine the harmonic artifact energy of the odd-order harmonic using the energy of the continuous ground-viewing scene, wherein the spatial harmonic point spread function is a complex impulse response generated using the fundamental SAR imaging operator; The suppression module 300 is used to compensate the coarse image using the harmonic artifact energy of all odd-order harmonics to obtain a SAR image after suppressing harmonic artifacts.

[0098] Based on the above-described single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function, this embodiment provides a computer-readable storage medium storing one or more programs, which can be executed by one or more processors to implement the steps in the single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function as described in the above embodiment.

[0099] Based on the above-mentioned single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function, this application also provides a terminal device, such as... Figure 8 As shown, it includes at least one processor 20; a display screen 21; and a memory 22, and may also include a communications interface 23 and a bus 24. The processor 20, display screen 21, memory 22, and communications interface 23 can communicate with each other via the bus 24. The display screen 21 is configured to display a preset user guide interface in the initial setup mode. The communications interface 23 can transmit information. The processor 20 can invoke logical instructions in the memory 22 to execute the methods described in the above embodiments.

[0100] Furthermore, the logical instructions in the aforementioned memory 22 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium.

[0101] The memory 22, as a computer-readable storage medium, can be configured to store software programs, computer-executable programs, such as program instructions or modules corresponding to the methods in the embodiments of this disclosure. The processor 20 executes functional applications and data processing by running the software programs, instructions, or modules stored in the memory 22, thereby implementing the methods in the above embodiments.

[0102] The memory 22 may include a program storage area and a data storage area. The program storage area may store the operating system and application programs required for at least one function; the data storage area may store data created based on the use of the terminal device. Furthermore, the memory 22 may include high-speed random access memory (RAM) and non-volatile memory. Examples include various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks, as well as transient storage media.

[0103] Furthermore, the specific process of loading and executing multiple instruction processors in the aforementioned storage medium and terminal device has been described in detail in the above method, and will not be repeated here.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for suppressing artifacts in single-bit SAR imaging based on spatially variable harmonic point spread function, characterized in that, The method includes: A coarse image is generated from a single-bit quantized echo using a fundamental wave SAR imaging operator, and the energy of a continuous ground scene is estimated based on the coarse image. For any odd-order harmonic, the continuous ground-to-ground scenario is divided into several scenario blocks; Harmonic echoes are constructed based on the fundamental echo phase of each scene block, and the harmonic echoes are processed using the fundamental SAR imaging operator to obtain the spatially variable harmonic point spread function of each scene block. A spatial harmonic wave point spread function is constructed for each spatial location in the continuous Earth-to-ground scene using the spatial harmonic wave point spread function of all scene blocks; Using the squared modulus of the spatial harmonic point spread function at each spatial location as the energy spread kernel, the harmonic artifact energy of the odd-order harmonics is determined using the continuous Earth scene energy, wherein the spatial harmonic point spread function is a complex impulse response generated using the fundamental wave SAR imaging operator. The coarse image is compensated using the harmonic artifact energy of all odd-order harmonics to obtain a SAR image with harmonic artifacts suppressed.

2. The single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function according to claim 1, characterized in that, The determination of the harmonic artifact energy of the odd-order harmonics using the squared modulus of the spatial harmonic point spread function at each spatial location as the energy spread kernel and the continuous Earth-view scene energy specifically includes: For each spatial location, an energy diffusion kernel is constructed using the squared modulus of the spatial harmonic point diffusion function of the spatial location, and the scene energy corresponding to the spatial location is read from the continuous Earth scene energy. The scene energy at all spatial locations is convolved with the energy diffusion kernel to obtain the harmonic artifact energy of the odd-order harmonics.

3. The single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function according to claim 1, characterized in that, The process of compensating the coarse image using the harmonic artifact energy of all odd-order harmonics to obtain a SAR image with suppressed harmonic artifacts specifically includes: Harmonic artifact energies of all odd-order harmonics are fused to obtain continuous harmonic artifact energies for the Earth scene. A true strong scattering threshold matrix is ​​constructed based on the coarse image, and a harmonic artifact gating weight matrix is ​​constructed based on the true strong scattering threshold matrix and the continuous ground scene harmonic artifact energy. The harmonic complex response of the continuous Earth-view scene is determined using the coarse image and the spatial harmonic point spread function at each spatial location in the continuous Earth-view scene. The coarse image is subjected to complex response cancellation using the harmonic complex response and the harmonic artifact gating weight matrix to obtain a SAR image with suppressed harmonic artifacts.

4. The single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function according to claim 3, characterized in that, The specific steps of constructing the harmonic artifact gating weight matrix based on the true strong scattering threshold matrix and the continuous Earth-oriented scene harmonic artifact energy include: A gated suppression matrix is ​​constructed based on the real strong scattering threshold matrix, and the gated suppression matrix is ​​superimposed with the harmonic artifact energy of the continuous Earth scene to obtain a weighted influence matrix; The ratio of the energy of the continuous ground scene harmonic artifacts to the weighted influence matrix is ​​obtained to obtain the harmonic artifact gating weight matrix.

5. The single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function according to claim 3, characterized in that, The determination of the harmonic complex response of the continuous Earth-view scene using the coarse image and the spatially varying harmonic point spread function at each spatial location in the continuous Earth-view scene specifically includes: The complex scattering coefficient matrix of the continuous Earth scene is constructed using the coarse image; The complex scattering coefficient matrix is ​​convolved with the spatial harmonic point spread function of each odd order at each spatial location to obtain the complex harmonic response of each odd order. The harmonic complex responses of all odd-order harmonics are fused to obtain the harmonic complex response of the continuous Earth-to-ground scenario.

6. The single-bit SAR imaging artifact suppression method based on spatially variable harmonic point spread function according to claim 3, characterized in that, After performing complex response cancellation on the coarse image using the harmonic complex response and the harmonic artifact gating weight matrix to obtain a SAR image with suppressed harmonic artifacts, the method further includes: An iterative harmonic inverse filter is constructed based on the spatial harmonic point spread function. The SAR image is subjected to iterative harmonic inverse filtering using the iterative harmonic inverse filter. The iterative harmonic inverse filter is expressed as: ， ， in, Indicates the first The main response to be recovered in the next iteration. Indicates the first The main response to be recovered in the next iteration. Indicates the iterative weights. Indicates the damping coefficient. Represents the parameters of the iterative inverse filter. Represents SAR images, Indicates the first The harmonic diffusion operator in the next iteration, Represents the point spread function of a spatially harmonic wave. Indicates the amplitude coefficient. It indicates odd order.

7. A single-bit SAR imaging artifact suppression device based on spatially variable harmonic point spread function, characterized in that, The device includes: The coarse image generation module is used to generate a coarse image for a single-bit quantized echo using a fundamental wave SAR imaging operator, and to estimate the energy of a continuous ground scene based on the coarse image. The harmonic energy determination module is used to divide the continuous ground-viewing scene into several scene blocks for any odd-order harmonic; construct harmonic echoes based on the fundamental echo phase of each scene block, and process the harmonic echoes using the fundamental SAR imaging operator to obtain the spatial harmonic point spread function of each scene block; construct a spatial harmonic point spread function for each spatial location in the continuous ground-viewing scene using the spatial harmonic point spread function of all scene blocks; use the squared modulus of the spatial harmonic point spread function at each spatial location as the energy diffusion kernel, and determine the harmonic artifact energy of the odd-order harmonic using the energy of the continuous ground-viewing scene, wherein the spatial harmonic point spread function is a complex impulse response generated using the fundamental SAR imaging operator; The suppression module is used to compensate the coarse image using the harmonic artifact energy of all odd-order harmonics to obtain a SAR image with suppressed harmonic artifacts.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores one or more programs, which can be executed by one or more processors to implement the steps in the single-bit SAR imaging artifact suppression method based on the spatially variable harmonic point spread function as described in any one of claims 1-6.

9. A terminal device, characterized in that, include: Processor and memory; The memory stores a computer-readable program that can be executed by the processor; When the processor executes the computer-readable program, it implements the steps in the single-bit SAR imaging artifact suppression method based on the spatially variable harmonic point spread function as described in any one of claims 1-6.

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