A method and apparatus for estimating and correcting ionospheric effects of spaceborne SAR

Abstract

This invention provides a method and apparatus for estimating and correcting ionospheric effects in spaceborne SAR, belonging to the fields of spaceborne SAR image processing technology and electromagnetic wave atmospheric transmission effect correction technology. The method includes: performing a range-direction Fourier transform on the SAR echo signal to obtain azimuth time-domain and range-frequency domain signals, and then dividing the signal into azimuth blocks to obtain azimuth block signals; selecting the azimuth block signals and performing coherent superposition and noise reduction on the block signals; estimating the ionospheric content of the denoised azimuth block signals to obtain an estimated value of ionospheric electron content, and obtaining the ionospheric electron content based on probability assessment; further obtaining estimated values ​​of ionospheric electron content corresponding to different azimuth block signals; performing ionospheric correction on the azimuth block signals respectively; and merging and outputting the ionospheric-corrected azimuth block signals. This invention, through azimuth block division and smoothing of estimated ionospheric intensity, can solve the problem of ionospheric estimation and correction caused by long synthetic aperture time.

Description

Technical Field

[0001] This invention belongs to the field of spaceborne SAR image processing technology and electromagnetic wave atmospheric transmission effect correction technology, and particularly relates to a method and device for estimating and correcting spaceborne SAR ionospheric effects. Background Technology

[0002] In the field of remote sensing, synthetic aperture radar (SAR) satellites play a crucial role in acquiring high-resolution images of the Earth's surface. However, the orbital altitude of SAR satellites (500km to 800km) requires their radar signals to cross the ionosphere twice during transmission—a partially ionized region in the Earth's atmosphere, ranging from approximately 50km to about 1000km from the ground. This process causes distortions in the amplitude and phase of the radar signal, thus affecting the quality of SAR images. Specifically, the group delay effect of the ionosphere causes a range-up shift in the image, dispersion reduces range resolution, and scintillation degrades azimuth resolution. From a technical perspective, spaceborne SAR ionospheric calibration techniques are mainly divided into two categories: one is the method of multi-point frequency measurement using external devices, and the other is the ionospheric estimation method based on SAR echo data processing.

[0003] Technical problems with existing technologies:

[0004] The stringent requirements for imaging conditions: Existing ionospheric intensity estimation and compensation methods based on SAR echo data typically require the presence of strong point targets in the imaging scene and a high signal-to-noise ratio in the image. However, SAR images that meet these conditions are relatively rare in practical applications, which greatly limits the applicability of this method.

[0005] High computational complexity and poor timeliness: Most existing ionospheric estimation methods employ non-parametric estimation, requiring multiple iterations to determine whether SAR image data meets imaging quality requirements, thereby assessing the accuracy of the ionospheric intensity estimate. This method suffers from high computational complexity and poor timeliness, typically only suitable for ground-based post-processing and unsuitable for future on-board real-time processing needs. Furthermore, this method requires data cross-correlation operations and usually necessitates 2 to 3 consecutive image imaging iterations, further increasing the computational burden and making it unsuitable for on-board processing workflows.

[0006] Challenges of High Resolution and Wide Imaging Swath: With the development of SAR technology, high-resolution and wide imaging swath SAR systems have gradually become mainstream. However, these systems generate enormous amounts of data, and existing ionospheric estimation and compensation methods are insufficient to effectively handle such massive amounts of data, thus making them unsuitable for high-resolution, wide imaging swath spaceborne SAR systems.

[0007] Spatiotemporal variability of ionospheric intensity: Spaceborne SAR imaging employs oblique-view geometry, and the ionospheric intensity along the azimuth of the radar wave changes spatiotemporally with the azimuth time-of-flight. In this context, relying solely on traditional single-frame echo data estimation methods is insufficient to accurately obtain ionospheric intensity values. Furthermore, SAR images typically contain multiple peak targets, which introduce randomness into the ionospheric autofocus estimation process, leading to erroneous ionospheric estimation results. Therefore, conventional ionospheric estimation procedures are insufficient to accurately obtain the actual ionospheric intensity values ​​in high-resolution spaceborne SAR systems. Summary of the Invention

[0008] To address the above technical problems, this invention proposes a method and apparatus for estimating and correcting ionospheric effects in spaceborne SAR, the specific technical solution of which is as follows:

[0009] A method for estimating and correcting ionospheric effects in spaceborne SAR, comprising:

[0010] Step 1: Perform range Fourier transform on the SAR echo signal to obtain the azimuth time-domain range-frequency domain signal; divide the azimuth time-domain range-frequency domain signal into blocks according to the azimuth direction to obtain the azimuth block signal.

[0011] Step 2: Select the azimuth block signal after segmentation based on the sliding window and perform coherent superposition and noise reduction to obtain the noise-reduced azimuth block signal;

[0012] Step 3: Perform ionospheric estimation on the denoised azimuth block signal to obtain the estimated ionospheric electron content, and obtain the ionospheric electron content of the azimuth block signal based on probability assessment.

[0013] Step 4: Estimate the ionospheric electron content of the segmented signals in different azimuth directions to obtain the estimated ionospheric electron content corresponding to the segmented signals in different azimuth directions;

[0014] Step 5: Smooth the estimated ionospheric electron content of the segmented sequence and perform ionospheric correction on the oriented segmented signals respectively;

[0015] Step 6: Merge the azimuth block signals after ionospheric correction and perform SAR imaging to output SAR images.

[0016] A spaceborne SAR ionospheric effect estimation and correction device includes:

[0017] The block module performs range-direction Fourier transform on the SAR echo signal to obtain the azimuth time-domain range-frequency domain signal; and performs azimuth-direction block processing on the azimuth time-domain range-frequency domain signal to obtain the azimuth-direction block signal.

[0018] The noise reduction module selects the azimuth block signal after segmentation based on a sliding window and performs coherent superposition noise reduction to obtain the noise-reduced azimuth block signal.

[0019] The evaluation module performs ionospheric estimation on the denoised azimuth block signal to obtain an estimated value of ionospheric electron content, and obtains the ionospheric electron content of the azimuth block signal based on probability evaluation; it also performs ionospheric electron content estimation on different azimuth block signals to obtain the estimated values ​​of ionospheric electron content corresponding to different azimuth block signals.

[0020] The correction module performs smooth fitting on the estimated ionospheric electron content of the segmented sequence and performs ionospheric correction on the oriented segmented signals respectively.

[0021] The output module merges the azimuth block signals after ionospheric correction and performs SAR imaging to output SAR images.

[0022] An electronic device includes: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to perform the aforementioned method.

[0023] A computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, cause the processor to perform the aforementioned method.

[0024] The present invention has the following beneficial effects:

[0025] This invention optimizes the data processing workflow through a one-dimensional data processing method, simplifying the originally complex two-dimensional matrix data processing into one-dimensional vector processing, significantly reducing the computational load and thus greatly improving the efficiency of ionospheric estimation and correction. Furthermore, this method solves the problem that traditional non-trigonometric ionospheric estimation methods based on SAR data cannot be processed on satellite.

[0026] This invention improves the signal-to-noise ratio of spaceborne SAR echo signals by using sliding window pulse coherent superposition, reduces the dependence of the self-focusing method on strong target scatterers in the scene, and has strong algorithm adaptability.

[0027] This invention solves the problem of estimating and correcting the space-variable ionosphere caused by long synthesis aperture time by using azimuth segmentation and smoothing of estimated ionospheric intensity. Attached Figure Description

[0028] Figure 1 This is a flowchart of the method of the present invention;

[0029] Figure 2 The graph shows the results of the subband spectrum test.

[0030] Figure 3 This is a sub-band imaging result image;

[0031] Figure 4 This is a diagram showing the ionosphere estimation results;

[0032] Figure 5 This is a histogram distribution of the ionosphere estimation results;

[0033] Figure 6 This is a diagram showing the relationship between subband spectrum tests.

[0034] Figure 7 This is a sub-band imaging result image;

[0035] Figure 8 This is a diagram showing the ionosphere estimation results;

[0036] Figure 9 This is a histogram showing the distribution of the ionosphere estimation results. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, this invention adopts the following technical solution.

[0038] This invention proposes a method for estimating and correcting ionospheric effects in spaceborne SAR, such as... Figure 1 As shown, it includes:

[0039] Step 1: Perform range Fourier transform on the SAR echo signal to obtain the azimuth time-domain range-frequency domain signal; divide the azimuth time-domain range-frequency domain signal into blocks according to the azimuth direction to obtain the azimuth block signal.

[0040] Step 2: Select the azimuth block signal after segmentation based on the sliding window and perform coherent superposition and noise reduction to obtain the noise-reduced azimuth block signal;

[0041] Step 3: Use the self-focusing method to estimate the ionospheric content of the denoised azimuth block signal, obtain the estimated value of the ionospheric electron content, and obtain the ionospheric electron content of the azimuth block signal based on probability assessment.

[0042] Step 4: Estimate the ionospheric electron content of the segmented signals in different azimuth directions to obtain the estimated ionospheric electron content corresponding to the segmented signals in different azimuth directions;

[0043] Step 5: Smooth the estimated ionospheric electron content of the segmented sequence and perform ionospheric correction on the oriented segmented signals respectively;

[0044] Step 6: Merge the azimuth block signals after ionospheric correction and perform SAR imaging to output SAR images.

[0045] Step 1 specifically involves processing the SAR echo signal. Perform a Fourier transform (FFT) in the range direction to obtain the azimuth time-domain and range-frequency domain signals. ,in, It is a one-dimensional frequency vector in the range direction. , This is represented as a range-direction Fourier transform; after performing azimuth-direction block division on the azimuth time-domain and range-frequency-domain signals, the azimuth-direction block signals are obtained as follows: ,in, This is a directional block sequence. , Number of blocks in the directional direction; This is a spaceborne SAR echo signal, in which, for Two-dimensional complex data matrix, For the direction of the point, The distance to the point;

[0046] Step 2 specifically involves selecting a signal. Chinese direction continuous A range-oriented one-dimensional signal is coherently combined and superimposed to obtain a coherently denoised range-oriented one-dimensional signal, denoted as . ,in Numbering of coherent superimposed signal sequences, , To estimate the number of algorithm iterations, ;

[0047] Step 3 further includes:

[0048] Step 31, process the denoised one-dimensional range signal. Each through subband bandwidth is The center frequency points are respectively and The bandpass filter yields two sub-band one-dimensional spectral signals. and The sub-band center frequency corresponds to the wavelength and ,in Among them, the range signal bandwidth of the spaceborne SAR system is ;

[0049] Step 32, for the two sub-band one-dimensional spectrum signals and Perform conjugate multiplication and inverse Fourier transform (IFFT), then process the IFFT result. The peak sampling point location obtained by doubling the sampling rate is denoted as . ,satisfy:

[0050] ;

[0051] Step 33, calculate the position offset. ,satisfy:

[0052] ,in The speed of light; The range signal sampling rate of the spaceborne SAR system;

[0053] Step 34, calculate the current The total electron content (TEC) of the ionosphere in the next iteration:

[0054] ;

[0055] in, It is a constant. .

[0056] Step 35: Generate ionospheric phase correction terms :

[0057] ;

[0058] Step 36, for the denoised one-dimensional range signal from step 2 Perform frequency domain phase multiplication to obtain ;

[0059] Step 37: Iterate and repeat steps 31 to 36 until the estimated total ionospheric electron content TEC meets the requirements. , The target residual total electron content value, or the number of iterations. Reaching the set number of iterations The total TEC estimate is ;

[0060] Step 38, slide the window position, repeat step 2 to select a new position. Given a range-directed one-dimensional signal, repeat the above steps to obtain the ionospheric estimate vector. The number of sliding window attempts is recorded as follows: ;

[0061] Step 39, the estimated value obtained in step 38 The vector values ​​are used for probability assessment, and the ionospheric TEC value at the point of highest probability is selected as the total ionospheric electron content for the current azimuth block time range. ;

[0062] Step 4 specifically involves repeating the above steps to obtain the ionospheric TEC value sequence corresponding to the azimuth block signal of the spaceborne SAR echo. A numerical smoothing fitting operation is then performed on the TEC sequence values ​​to obtain the estimated azimuth block ionospheric values. , Number of blocks in the directional direction;

[0063] Step 5 further includes:

[0064] Step 51: Perform frequency domain ionospheric phase correction on the azimuth block signal of the spaceborne SAR echo. The correction phase is... :

[0065] ;

[0066] in, For the carrier frequency of the spaceborne SAR system;

[0067] Step 52: Perform azimuth-oriented block signal stitching and spaceborne SAR echo imaging.

[0068] Specific embodiments of the technical solution of the present invention:

[0069] Taking the processing of satellite-borne SAR echo data from a scene in a domestic urban area as an example, the parameters are shown in the table below:

[0070]

[0071] Some of the simulation images are shown below. Figure 2 This is a schematic diagram of the spectral relationship of the sub-band self-focusing method adopted after coherent frame overlay. Figure 3 For the corresponding Figure 2 A schematic diagram of the one-dimensional spectral imaging results in the image. Figure 4 This is the estimation result of the total ionospheric electron content (TEC) value corresponding to the 901 merged frames obtained after the execution of the steps of this invention. Figure 5 Based on Figure 4 The probability distribution statistics of the ionospheric TEC estimation results in frame 901 are shown in the figure, where the peak position corresponds to the TEC range. TECU.

[0072] according to Figure 4The distribution of ionospheric TEC estimation results reveals that these estimates exhibit dynamic changes, and a single estimate can deviate from the actual ionospheric intensity. Therefore, based on... Figure 5 The mid-ionospheric assessment results determine the final ionospheric TEC to be 53 TECU, achieving an accurate estimate of the ionospheric intensity.

[0073] The results of the control group of the example are also given here. Figures 6-9 As shown, the control group experiment was based on the same spaceborne SAR echo data and did not employ azimuth-directed sliding windowing for azimuth-directed frame coherent stacking. In contrast, the control group experiment showed drastic fluctuations in the estimated ionospheric intensity TEC value, which severely affected the final ionospheric TEC estimation result. Figure 8 , Figure 9 As shown; in comparison, the technical method of the present invention can significantly improve the effectiveness of ionosphere estimation.

[0074] The azimuth segmentation method in step 1 has different segmentation strategies and methods depending on different spatial variation states, and can be replaced. For example, in general long synthetic aperture imaging, azimuth segmentation is performed based on the secondary phase coefficient, dense segmentation is performed at high curvature of range migration, and sparse segmentation is performed at low curvature of range migration.

[0075] Steps 31 to 37 are variations of the ionospheric estimation method based on the subband correlation autofocus algorithm, which improves the two-dimensional image autofocus to one-dimensional data autofocus, representing an improvement in computational efficiency. Besides the subband correlation method, this method can be extended to other ionospheric estimation methods, such as the Phase Adjustment by Contrast Enhancement (PACE), maximum entropy autofocus, maximum image sharpness autofocus, metric-optimized deep network estimation, image autofocus based on Discrete Cosine Transform (DCT), phase gradient autofocus (PGA), MapDrift image phase estimation, and other improved ionospheric estimation methods based on the aforementioned approaches.

[0076] This invention also proposes a spaceborne SAR ionospheric effect estimation and correction device, comprising:

[0077] The block module performs range-direction Fourier transform on the SAR echo signal to obtain the azimuth time-domain range-frequency domain signal; and performs azimuth-direction block processing on the azimuth time-domain range-frequency domain signal to obtain the azimuth-direction block signal.

[0078] The noise reduction module selects the azimuth block signal after segmentation based on a sliding window and performs coherent superposition noise reduction to obtain the noise-reduced azimuth block signal.

[0079] The evaluation module performs ionospheric estimation on the denoised azimuth block signal to obtain an estimated value of ionospheric electron content, and obtains the ionospheric electron content of the azimuth block signal based on probability evaluation; it also performs ionospheric electron content estimation on different azimuth block signals to obtain the estimated values ​​of ionospheric electron content corresponding to different azimuth block signals.

[0080] The correction module performs smooth fitting on the estimated ionospheric electron content of the segmented sequence and performs ionospheric correction on the oriented segmented signals respectively.

[0081] The output module merges the azimuth block signals after ionospheric correction and performs SAR imaging to output SAR images.

[0082] The present invention also proposes an electronic device comprising: one or more processors; and a memory for storing one or more programs, wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned method.

[0083] The present invention also proposes a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, cause the processor to implement the aforementioned method.

[0084] 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 implemented 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. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0085] 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.

[0086] 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.

[0087] 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 1 The steps of the function specified in one or more boxes.

[0088] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0089] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A space-borne SAR ionospheric effect estimation and correction method, characterized in that, The method comprises the following steps: Step 1: performing distance Fourier transform on the SAR echo signal to obtain azimuth time domain distance frequency domain signals; performing azimuth block processing on the azimuth time domain distance frequency domain signals to obtain azimuth block signals; Step 2: selecting and performing coherent superposition noise reduction on the block processed azimuth block signals based on a sliding window to obtain the noise reduced azimuth block signals; Step 3: performing ionospheric estimation on the noise reduced azimuth block signals to obtain ionospheric electron content estimation values, and obtaining ionospheric electron content of the azimuth block signals based on probability estimation; Step 4: performing ionospheric electron content estimation on different azimuth block signals to obtain ionospheric electron content estimation values corresponding to the different azimuth block signals; Step 5: performing smoothing fitting on the block sequence ionospheric electron content estimation values, and performing ionospheric correction on the azimuth block signals respectively; Step 6: merging the ionospherically corrected azimuth block signals, and performing SAR imaging to output a SAR image.

2. The method according to claim 1, wherein, The step 1 is specifically, performing Fourier transform on the SAR echo signal performing Fourier transform on the distance direction to obtain a range-time-frequency signal wherein, is a one-dimensional frequency vector in the distance direction, , denotes the Fourier transform in the distance direction; performing block division in the azimuth direction on the range-time-frequency signal to obtain a range-time-frequency block signal wherein is a block sequence in the azimuth direction, , is the number of block division in the azimuth direction; is a spaceborne SAR echo signal, wherein, is a two-dimensional complex data matrix of , is the number of points in the azimuth direction, is the number of points in the distance direction.

3. The method according to claim 2, wherein the ionospheric effect is estimated by using the following equation: ###0001### wherein, f is the frequency of the transmitted signal, h is the height of the satellite, and c is the speed of light. Step 2 is specifically selecting signals mid-azimuth continuous one-dimensional signals in the range direction, and the coherent de-noised one-dimensional signals in the range direction are obtained by coherent superposition and stacking, and are marked as , wherein is the sequence number of the coherent superposition signals, , is the iteration number of the estimation algorithm, . ​ 4. The method according to claim 3, wherein the ionospheric effect is estimated by using the following equation: ###0002### wherein, f is the frequency of the transmitted signal, h is the height of the satellite, and c is the speed of light. Step 3 further comprises: Step 31, the one-dimensional signal of the distance direction after noise reduction respectively through the band-pass filter with the sub-band bandwidth of , the center frequency position of and , two one-dimensional spectrum signals of the sub-band and are obtained, the center frequency points of the sub-band correspond to the wavelength of and , wherein ; wherein, the signal bandwidth of the distance direction of the space-borne SAR system is ; Step 32, for the two sub-band one-dimensional spectrum signals and Perform conjugate multiplication and inverse Fourier transform (IFFT), then process the IFFT result. The peak sampling point location obtained by doubling the sampling rate is denoted as . ,satisfy: ； Step 33, calculate position offset , satisfies: wherein is the speed of light; is the range signal sampling rate of the space-borne SAR system; Step 34, calculate current Ionospheric Total Electron Content TEC for the current ； wherein is a constant; Step 35, generating ionospheric phase correction term : ； Step 36, for the denoised one-dimensional range signal from step 2 Perform frequency domain phase multiplication to obtain ; Step 37, iteratively repeat steps 31 to 36 until the ionosphere total electron content TEC of this estimation meets , target residual total electron content value, or the number of iterations reaches the set number of iterations , the total TEC estimation value is ; Step 38, sliding window position, repeat step 2 to select a new distance vector one-dimensional signal, and repeat the above steps to obtain the ionosphere estimate vector , the number of sliding window is recorded as ; Step 39, the ionospheric TEC value at the maximum probability is selected as the ionospheric TEC value of the current azimuthal block time range The vector value is subjected to probability evaluation, and the ionospheric TEC value at the maximum probability is selected as the ionospheric TEC value of the current azimuthal block time range .

5. The method for estimating and correcting ionospheric effects of spaceborne SAR according to claim 4, characterized in that, The step 4 is specifically repeating the step 3 to obtain the ionospheric TEC value sequence corresponding to the azimuth direction block signal of the spaceborne SAR echo, and performing numerical smoothing fitting operation on the TEC sequence value to obtain the azimuth direction block ionospheric estimation value , is the azimuth direction block number.

6. The method for estimating and correcting ionospheric effects of spaceborne SAR according to claim 5, characterized in that, Step 5 comprises: Step 51, the ionospheric phase correction in frequency domain is performed on the azimuth block signal of the space-borne SAR echo, and the correction phase is : ； wherein, is the carrier frequency of the spaceborne SAR system; Step 52: performing azimuth block signal splicing and spaceborne SAR echo imaging.

7. The method of claim 1, wherein the ionospheric effect is estimated and corrected by using a model of the ionosphere. The azimuth block in step 1 is specifically: Performing azimuth block according to the quadratic phase coefficient, performing dense block at the moment of high distance migration curvature, and performing sparse block at the moment of low distance migration curvature.

8. A space-borne SAR ionospheric effects estimation and correction apparatus, characterized in that, The method comprises the following steps: The block module performs distance Fourier transform on the SAR echo signal to obtain azimuth time domain distance frequency domain signals; performs azimuth block processing on the azimuth time domain distance frequency domain signals to obtain azimuth block signals; The noise reduction module selects and performs coherent superposition noise reduction on the block processed azimuth block signals based on a sliding window to obtain the noise reduced azimuth block signals; The estimation module performs ionospheric estimation on the noise reduced azimuth block signals to obtain ionospheric electron content estimation values, and obtains ionospheric electron content of the azimuth block signals based on probability estimation; performs ionospheric electron content estimation on different azimuth block signals to obtain ionospheric electron content estimation values corresponding to the different azimuth block signals; The correction module performs smoothing fitting on the block sequence ionospheric electron content estimation values, and performs ionospheric correction on the azimuth block signals respectively; The output module merges the ionospherically corrected azimuth block signals, and performs SAR imaging to output a SAR image.

9. An electronic device, comprising: The method comprises the following steps: One or more processors; A memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the method of any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, Executable instructions are stored thereon, which are executed by a processor to enable the processor to implement the method of any one of claims 1 to 7.

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