An improved WVD-based space-borne SAR moving target imaging method

Abstract

The application discloses a kind of based on the spaceborne SAR moving target imaging method of improved WVD, belong to signal processing field.Method includes: according to the simulation scene parameter of the spaceborne SAR moving target to be imaged obtained and the signal simulation parameter and the scene point coordinate of simulation scene calculated, generate simulation echo signal;Original echo signal and simulation echo signal are compressed in distance, and the compressed signal is corrected to distance migration according to azimuth frequency after azimuth Fourier transform processing, obtain correction signal;The point in the WVD curve of correction signal meets the point of threshold requirement and is linearly fitted, and the estimated value of Doppler center frequency and Doppler frequency modulation is calculated according to fitting result;The product of correction signal and preset azimuth frequency filter is calculated, and the imaging result of spaceborne SAR moving target is obtained by inverse Fourier transform to calculation result.The application can improve the imaging quality of spaceborne SAR moving target.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of signal processing, in particular to a spaceborne SAR moving target imaging method based on improved WVD. BACKGROUND

[0002] Synthetic Aperture Radar (SAR) is an active microwave sensor, which works regardless of cloud environment and other factors, and has the characteristics of high resolution and wide detection range, and is widely used in agriculture and geology. Moving target detection and imaging has always been an important application of spaceborne synthetic aperture radar. In order to realize accurate imaging of moving targets, their accurate Doppler parameters need to be obtained, but in actual application scenarios, the true motion parameters of the target are difficult to know, and the method of time-frequency analysis needs to be used to estimate the Doppler parameters.

[0003] In related technologies, Wigner Ville Distribution (WVD) is an effective time-frequency analysis tool, which can be combined with Hough Transform (HT) to realize imaging of moving targets through a series of processes. However, WVD is susceptible to cross terms, which can cause artifacts in the final results. If the Hough transform is used directly without optimization, it will cause calculation errors in the parameter estimation process, and thus result in low imaging quality.

[0004] Therefore, there is an urgent need for a spaceborne SAR moving target imaging method based on improved WVD to solve the above technical problems. SUMMARY

[0005] The present application provides a spaceborne SAR moving target imaging method based on improved WVD, which can solve the problem of low imaging quality in related technologies. The technical solution is as follows:

[0006] On the one hand, a spaceborne SAR moving target imaging method based on improved WVD is provided, which comprises:

[0007] According to the obtained simulation scene parameters of the spaceborne SAR moving target to be imaged and the calculated signal simulation parameters and scene point coordinates of the simulation scene, a simulation echo signal is generated;

[0008] The original echo signal and the simulation echo signal are subjected to range compression, and the compressed signal subjected to azimuth Fourier transform processing is subjected to range migration correction according to the azimuth frequency, to obtain a corrected signal;

[0009] The points in the WVD curve of the corrected signal that meet the threshold requirement are subjected to linear fitting, and the estimated values of the Doppler center frequency and the Doppler frequency modulation are calculated according to the fitting result.

[0010] The product of the correction signal and a preset azimuth frequency filter is calculated, and inverse Fourier transform is performed on the calculation result to obtain the imaging result of the spaceborne SAR moving target; wherein the azimuth frequency filter is established according to the azimuth frequency, the Doppler center frequency and the Doppler frequency modulation.

[0011] In another aspect, a spaceborne SAR moving target imaging device based on the improved WVD is provided, and the device comprises:

[0012] A generating module is configured to generate a simulation echo signal according to the acquired simulation scene parameters of the spaceborne SAR moving target to be imaged, and the calculated signal simulation parameters and scene point coordinates of the simulation scene.

[0013] A correction module is configured to perform range compression on the original echo signal and the simulation echo signal, and perform range migration correction on the compressed signals processed by azimuth Fourier transform according to the azimuth frequency to obtain a correction signal.

[0014] A first calculating module is configured to perform linear fitting on the points in the WVD curve of the correction signal that meet the threshold requirement, and calculate the estimated values of the Doppler center frequency and the Doppler frequency modulation according to the fitting result.

[0015] A second calculating module is configured to calculate the product of the correction signal and a preset azimuth frequency filter, and perform inverse Fourier transform on the calculation result to obtain the imaging result of the spaceborne SAR moving target; wherein the azimuth frequency filter is established according to the azimuth frequency, the Doppler center frequency and the Doppler frequency modulation.

[0016] In another aspect, a computer device is provided, which comprises a memory and a processor, the memory is configured to store a computer program, and the processor is configured to execute the computer program stored in the memory to realize the steps of the spaceborne SAR moving target imaging method based on the improved WVD.

[0017] In another aspect, a computer readable storage medium is provided, and the storage medium stores a computer program, the computer program is executed by a processor to realize the steps of the spaceborne SAR moving target imaging method based on the improved WVD.

[0018] In another aspect, a computer program product is provided, which comprises a computer program, the computer program is executed by a processor to realize the steps of the spaceborne SAR moving target imaging method based on the improved WVD.

[0019] The technical scheme provided by the application can bring at least the following beneficial effects: firstly, based on the input radar parameters and scene parameters, key parameters such as reference slant range and frequency modulation rate are calculated, and a moving target three-dimensional scene is arranged. Then, the moving target simulation echo signal is generated and distance compression processing is performed. In view of the distance migration effect caused by the moving target, the signal is corrected by combining the phase filtering method and the azimuth frequency analysis. Then, the WVD is used for time-frequency analysis, the signal energy concentration area is extracted, and the Doppler center frequency and the frequency modulation rate are inversely calculated through linear fitting, the azimuth direction matching filter is constructed and multiplied by the corrected signal, and finally the moving target imaging is completed. The application can realize filtering of the WVD result, limit the range of selected calculation points, and thus improve the linear fitting precision and the precision of the Doppler parameter estimation result, and finally improve the quality of the moving target imaging. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical scheme in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 is a flow chart of a spaceborne SAR moving target imaging method based on improved WVD provided by an embodiment of the application;

[0022] Figure 2 is an effect diagram of a traditional WVD method processing provided by an embodiment of the application;

[0023] Figure 3 is an effect diagram of an improved WVD method processing provided by an embodiment of the application;

[0024] Figure 4 is a moving target imaging result diagram using non-adaptive Doppler parameters provided by an embodiment of the application;

[0025] Figure 5 is a moving target imaging result using Doppler parameters estimated by an improved WVD method provided by an embodiment of the application;

[0026] Figure 6 is a structure diagram of a spaceborne SAR moving target imaging device based on improved WVD provided by an embodiment of the application;

[0027] Figure 7 is a hardware architecture diagram of a computer device provided by an embodiment of the application. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] As mentioned earlier, WVD in related technologies is susceptible to the influence of cross terms, which can cause artifacts in the final result. If the Hough transform is used directly without optimization, the artifacts will cause calculation errors in the parameter estimation process, thus affecting the final image quality.

[0030] Based on this, the present invention proposes an improved WVD-based spaceborne SAR moving target imaging method, which, compared with existing methods, can image moving targets quickly, efficiently and accurately.

[0031] The following describes the specific implementation of the above concept.

[0032] Please refer to Figure 1 This invention provides a spaceborne SAR moving target imaging method based on improved WVD, the method comprising:

[0033] Step 100: Generate a simulated echo signal based on the obtained simulated scene parameters of the moving target on the spaceborne SAR to be imaged, the calculated simulated signal parameters, and the scene point coordinates of the simulated scene.

[0034] Step 102: Perform range compression on the original echo signal and the simulated echo signal, and perform range migration correction on the compressed signal processed by the azimuth Fourier transform according to the azimuth frequency to obtain the corrected signal.

[0035] Step 104: Perform linear fitting on the points in the WVD curve of the corrected signal that meet the threshold requirements, and calculate the estimated values ​​of the Doppler center frequency and the Doppler modulation frequency based on the fitting results.

[0036] Step 106: Calculate the product of the correction signal and the preset azimuth frequency filter, and perform an inverse Fourier transform on the calculation result to obtain the imaging result of the spaceborne SAR moving target; wherein, the azimuth frequency filter is established based on the azimuth frequency, the Doppler center frequency and the Doppler modulation frequency.

[0037] In the embodiment of the present application, firstly, the key parameters such as reference slant range and frequency modulation are calculated based on the input radar parameters and scene parameters, and a three-dimensional scene of moving target is arranged. Then, the simulation echo signal of the moving target is generated and distance compression processing is performed. In view of the distance migration effect caused by the moving target, the signal is corrected by combining the phase filtering method and azimuth frequency analysis. Then, the WVD is used for time-frequency analysis, the signal energy concentration region is extracted, and the Doppler center frequency and frequency modulation are inversely calculated by linear fitting, the azimuth matched filter is constructed and multiplied by the corrected signal, and finally the moving target imaging is completed. The present application can realize filtering of the WVD result, limit the range of selected calculation points, and thus improve the linear fitting precision and the precision of Doppler parameter estimation result, and finally improve the quality of moving target imaging.

[0038] The execution mode of each step shown below is described. Figure 1 The execution mode of each step shown below is described.

[0039] Firstly, for step 100, the simulation echo signal is generated according to the obtained simulation scene parameters of the spaceborne SAR moving target to be imaged and the calculated signal simulation parameters and scene point coordinates of the simulation scene.

[0040] In the embodiment of the present application, the simulation scene parameters include radar signal wavelength λ, pulse width tao, bandwidth B w , sampling rate f s , pulse repetition frequency PRF, slant angle Azimuth sampling point number N a , distance sampling point number N r , radar speed v radar , radar height h radar , downward angle θ, antenna length L a , azimuth arrangement point number Num ver , distance arrangement point number Num hor , azimuth point interval distance dis ver , distance point interval distance dis hor , target azimuth speed V a , target distance speed V r .

[0041] Further, the signal simulation parameters required in subsequent simulation are calculated according to the above-mentioned obtained data, including reference slant range R ref , distance effective sampling point number Num valid_range , frequency modulation K r , synthetic aperture time T s , distance gate dis rangebin , and the specific method is as follows:

[0042]

[0043] Num valid_range = floor(fs*tao)

[0044]

[0045] Further, according to the data obtained above, scene arrangement is completed, including calculation of scene center three-dimensional coordinates X c ,Y c ,Z c , and calculation of coordinates of arranged points. The specific operation process is as follows:

[0046] The scene center three-dimensional coordinates X c ,Y c ,Z c are calculated.

[0047]

[0048] Then, according to the scene center three-dimensional coordinates, the coordinates of each point of the arranged point array are calculated.

[0049] Finally, according to the data obtained above and the calculation results, the SAR simulation echo signal is generated. The specific operation process is as follows: the slow time axis t a is calculated; the coordinates (x radar ,y radar ,z radar ) of the radar in the slow time axis are calculated; the coordinates (x tar ,y tar ,z tar ) of the arranged target point in the slow time axis are calculated; the fast time axis t r is calculated; and finally the simulation echo signal is calculated. The calculation process is well known to those skilled in the art, and will not be described here.

[0050] Then, for step 102, the original echo signal and the simulation echo signal are range compressed, and the compressed signals subjected to azimuth Fourier transform processing are range migrated according to azimuth frequency, to obtain a corrected signal.

[0051] In the embodiment of the application, the original echo signal and the simulation echo signal are range compressed, including: frequency alignment processing of the original echo signal and the simulation echo signal converted to the frequency domain; calculation of the product of the two signals after alignment processing, and inverse Fourier transform of the calculation result; and traversal processing of each row of data subjected to inverse Fourier transform, to obtain a compressed signal after range compression.

[0052] Specifically, according to the obtained data N r , B w , f sand the calculated parameter K r , a distance compression matching filter is constructed, and the original echo signal is combined with the filter to complete the range compression of the synthetic aperture radar echo signal.

[0053] Further, according to the obtained data N a and N r , the range compressed compressed signal is subjected to azimuth Fourier transform. The detailed operation is to keep the row unchanged, traverse each column, perform Fourier transform and then align the frequency.

[0054] In the embodiment of the application, the range migration correction is performed on the compressed signal subjected to the azimuth Fourier transform processing according to the azimuth frequency, and a corrected signal is obtained, comprising:

[0055] According to the simulation scene parameters N a , N r and PRF, the azimuth frequency f a is calculated, and the target range migration ΔR is calculated according to the simulation scene parameters and the signal simulation parameters:

[0056]

[0057] wherein, R ref is a reference slant range; v radar is a radar speed; and λ is a radar signal wavelength;

[0058] According to the target range migration, a phase filter H(f r ) is constructed:

[0059]

[0060] wherein, j is an imaginary unit, and c is the speed of light;

[0061] The compressed signal subjected to the azimuth Fourier transform processing is multiplied by the phase filter after Fourier transform, and the product result is subjected to inverse Fourier transform, so as to obtain the corrected signal.

[0062] For step 104, the points in the WVD curve of the corrected signal satisfying the threshold requirement are subjected to linear fitting, and the estimated values of the Doppler center frequency and the Doppler frequency modulation are calculated according to the fitting result.

[0063] In the embodiment of the application, the WVD of the echo signal is calculated by using the interpolation method, and the WVD curve of the echo signal is drawn with the azimuth frequency and the range frequency as the coordinate axes. The WVD curve of the corrected signal x(t) is:

[0064]

[0065] Wherein, f is signal frequency; Tau is integral variable.

[0066] In the embodiment of the application, the points in the WVD curve of the correction signal satisfying the threshold requirement are linearly fitted, and the estimated values of the Doppler center frequency and the Doppler frequency modulation are calculated according to the fitting results, comprising:

[0067] The threshold threhold is determined according to the maximum value of the amplitude of the WVD curve:

[0068] threhold = alpha max{max{abs(W(t,f))}

[0069] Wherein, max{·} is the maximum value function; abs(W(t,f)) is the amplitude of the WVD curve;

[0070] The points in the WVD curve satisfying the threshold requirement are extracted and linearly fitted, and the slope and intercept of the fitting straight line are calculated;

[0071] The estimated value of the Doppler center frequency And the estimated value of the Doppler frequency modulation

[0072]

[0073] Wherein, The estimated value of the slope of the fitting straight line; The estimated value of the intercept of the fitting straight line.

[0074] For step 106, the product of the correction signal and the preset azimuth frequency filter is calculated, and the inverse Fourier transform is performed on the calculation result to obtain the imaging result of the spaceborne SAR moving target.

[0075] In the embodiment of the application, the azimuth frequency filter H azimuth (f) according to the azimuth frequency, the Doppler center frequency and the Doppler frequency modulation:

[0076]

[0077] In the formula, j is the imaginary unit; Pi is the circular constant; f a Is the azimuth frequency.

[0078] Then the correction signal and the azimuth frequency filter are multiplied, and the product is inverse Fourier transformed to obtain the imaging result of the moving target.

[0079] The feasibility of the above method is demonstrated by an embodiment as follows:

[0080] The parameters required in the simulation calculation process are shown in Table 1.

[0081] Table 1

[0082]

[0083]

[0084] After the above steps, the star-borne SAR moving target imaging result based on the improved WVD can be obtained. Figure 2 is an effect diagram processed by the traditional WVD method. Figure 3 is an effect diagram processed by the improved WVD method. Figure 4 is a moving target imaging result diagram using the inadapted Doppler parameter. Figure 5 is a moving target imaging result diagram using the Doppler parameter estimated by the improved WVD method. Figure 2 and Figure 3 It can be seen that the traditional WVD method selects more false target points when selecting points, while the improved WVD method focuses on the effective points in the local region of the energy peak when selecting points. Figure 4 and Figure 5 It can be seen that the imaging using the inadapted Doppler parameter will cause defocusing and offset of the imaging result, while the moving target imaging method based on the improved WVD method can make the final imaging effect have better focusing effect and not offset, thereby obtaining better imaging quality.

[0085] Please refer to Figure 6 The embodiment of the present application provides a star-borne SAR moving target imaging device based on the improved WVD, which comprises:

[0086] A generation module 600 is configured to generate a simulation echo signal according to the simulation scene parameters of the star-borne SAR moving target to be imaged, the calculated signal simulation parameters and the scene point coordinates of the simulation scene.

[0087] A correction module 602 is configured to perform distance compression on the original echo signal and the simulation echo signal, and perform distance migration correction on the compressed signal processed by the azimuth Fourier transform according to the azimuth frequency, to obtain a corrected signal.

[0088] A first calculation module 604 is configured to perform linear fitting on the points in the WVD curve of the corrected signal that meet the threshold requirement, and calculate the estimated values of the Doppler center frequency and the Doppler frequency modulation according to the fitting result.

[0089] The second calculation module 606 is configured to calculate a product of the correction signal and a preset azimuth frequency filter, and perform inverse Fourier transform on the calculation result to obtain the imaging result of the space-borne SAR moving target, wherein the azimuth frequency filter is established according to the azimuth frequency, the Doppler center frequency and the Doppler frequency modulation.

[0090] In the embodiment of the present application, the correction module 602 is configured to perform the following operations when performing distance compression on the original echo signal and the simulated echo signal:

[0091] performing frequency alignment processing on the original echo signal and the simulated echo signal converted to the frequency domain;

[0092] calculating the product of the two signals after the alignment processing, and performing inverse Fourier transform on the calculation result;

[0093] performing traversal processing on each row of data after the inverse Fourier transform to obtain the compressed signal after the distance compression.

[0094] In the embodiment of the present application, the correction module 602 is configured to perform the following operations when performing distance migration correction on the compressed signal after the azimuth Fourier transform processing according to the azimuth frequency to obtain the correction signal:

[0095] calculating the azimuth frequency f a according to the simulated scene parameters, and calculating the target distance migration AR according to the simulated scene parameters and the signal simulation parameters:

[0096]

[0097] wherein, R ref is a reference slant range; v radar is a radar speed; and λ is a radar signal wavelength;

[0098] constructing a phase filter H(f r ) according to the target distance migration:

[0099]

[0100] wherein, j is an imaginary unit, and c is a light speed;

[0101] multiplying the compressed signal after the azimuth Fourier transform processing by the phase filter, and performing inverse Fourier transform on the product result to obtain the correction signal.

[0102] In the embodiment of the present application, the WVD curve of the correction signal is as follows:

[0103]

[0104] where f is the signal frequency; τ is the integral variable; and x(t) is the correction signal.

[0105] In the embodiment of the present application, when the first calculation module 604 performs linear fitting on the points in the WVD curve of the correction signal that meet the threshold requirement, and calculates the estimated values of the Doppler center frequency and the Doppler frequency modulation according to the fitting result, the first calculation module 604 is specifically configured to perform the following operations:

[0106] The threshold threhold is determined according to the maximum value of the amplitude of the WVD curve:

[0107] threhold = αmax{max{abs(W(t,f))}}

[0108] where max{·} is the maximum value function; and abs(W(t,f)) is the amplitude of the WVD curve.

[0109] The points in the WVD curve that meet the threshold requirement are extracted and linear fitting is performed, and the slope and the intercept of the fitting straight line are calculated.

[0110] The estimated value of the Doppler center frequency and the estimated value of the Doppler frequency modulation

[0111]

[0112] where is the estimated value of the slope of the fitting straight line. is the estimated value of the intercept of the fitting straight line.

[0113] In the embodiment of the present application, the azimuth frequency filter H azimuth is established by the following formula:

[0114]

[0115] where j is the imaginary unit; π is the circular constant; f a is the azimuth frequency.

[0116] It should be noted that the above embodiment provides the star-borne SAR moving target imaging device based on the improved WVD, and only the above functional modules are exemplified, and in actual application, the above functions can be distributed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the star-borne SAR moving target imaging device based on the improved WVD provided by the above embodiment and the star-borne SAR moving target imaging method based on the improved WVD embodiment belong to the same concept, and the specific implementation process is detailed in the method embodiment, which will not be repeated here.

[0117] Embodiments of the present application also provide a computer device, which refers to Figure 7 The computer device includes a processor and a memory, and the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor to implement the star-borne SAR moving target imaging method based on the improved WVD provided by each method embodiment.

[0118] Embodiments of the present application also provide a computer readable storage medium, which stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor to implement the star-borne SAR moving target imaging method based on the improved WVD provided by each method embodiment.

[0119] Embodiments of the present application also provide a computer program product, which includes a computer program, and the processor of the computer device reads the computer program from the computer readable storage medium, and the processor executes the computer program, so that the computer device executes the star-borne SAR moving target imaging method based on the improved WVD described in any of the above embodiments.

[0120] For the convenience of description, the above system or device is described as various modules or units respectively described in function. Of course, in the implementation of the present application, the functions of each unit can be implemented in the same or more software and / or hardware.

[0121] Those skilled in the art can clearly understand the application by the description of the above embodiments. The technical solutions of the application can be implemented by means of software and necessary universal hardware platforms. Based on such an understanding, the technical solutions of the application can be embodied in the form of a software product, which can be stored in a storage medium, such as a ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of the application.

[0122] Finally, it should be noted that the terms such as first, second, third, and fourth, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0123] The above description is only the preferred embodiments of the application, and it should be pointed out that those skilled in the art can make some improvements and refinements without departing from the principles of the application, and these improvements and refinements should also be regarded as the protection scope of the application.

Claims

1. A method for space-borne SAR moving target imaging based on improved WVD, characterized in that, The method comprises: According to the obtained simulation scene parameters of the spaceborne SAR moving target to be imaged and the calculated signal simulation parameters and scene point coordinates of the simulation scene, a simulation echo signal is generated; The original echo signal and the simulation echo signal are subjected to range compression, and the compressed signal subjected to azimuth Fourier transform processing is subjected to range migration correction according to the azimuth frequency, to obtain a corrected signal, comprising: The azimuth frequency is calculated according to the simulation scene parameter f a The target distance migration is calculated according to the simulation scene parameter and the signal simulation parameter : wherein, is the reference slant range; is the radar speed; is the radar signal wavelength; Constructing a phase filter according to the target distance migration H ( f r ) wherein j is the imaginary unit, c is the speed of light; The compressed signal subjected to azimuth Fourier transform processing is subjected to Fourier transform, multiplied by the phase filter, and subjected to inverse Fourier transform of the product, to obtain the corrected signal; The points in the WVD curve of the corrected signal that meet the threshold requirement are subjected to linear fitting, and the estimated values of the Doppler center frequency and the Doppler frequency modulation are calculated according to the fitting result; The WVD curve of the corrected signal is: in, f The signal frequency; τ For integration variables; x ( t () is the correction signal; The product of the correction signal and a preset azimuth frequency filter is calculated, and the inverse Fourier transform is performed on the calculation result to obtain the imaging result of the space-borne SAR moving target, including: determining the threshold according to the maximum value of the amplitude of the WVD curve The points in the WVD curve that meet the threshold requirement are extracted and subjected to linear fitting, and the slope and intercept of the fitting straight line are calculated; : wherein is the maximum value function; is the amplitude of the WVD curve; The azimuth frequency filter is established according to the azimuth frequency, the Doppler center frequency and the Doppler frequency modulation. An estimate of the Doppler center frequency is obtained from the slope and intercept of the fitted line and an estimate of the Doppler frequency rate : wherein is an estimate of the slope of the fitted straight line; is an estimate of the intercept of the fitted straight line; The original echo signal and the simulation echo signal are subjected to range compression, comprising: wherein j is the imaginary unit; π is the ratio of the circumference of a circle to its diameter; f a is the azimuthal frequency.

2. The method of claim 1, wherein, The original echo signal and the simulation echo signal converted to the frequency domain are subjected to frequency alignment processing; The product of the two signals subjected to alignment processing is calculated, and the calculation result is subjected to inverse Fourier transform; Each row of data subjected to inverse Fourier transform is subjected to traversal processing, to obtain the compressed signal subjected to range compression. The device is applied to the method of any one of claims 1-2, and the device comprises:

3. An improved WVD-based space-borne SAR moving target imaging apparatus, characterized in that, A generation module is configured to generate a simulation echo signal according to the obtained simulation scene parameters of the spaceborne SAR moving target to be imaged and the calculated signal simulation parameters and scene point coordinates of the simulation scene; A correction module is configured to subject the original echo signal and the simulation echo signal to range compression, and subject the compressed signal subjected to azimuth Fourier transform processing to range migration correction according to the azimuth frequency, to obtain a corrected signal; A first calculation module is configured to subject the points in the WVD curve of the corrected signal that meet the threshold requirement to linear fitting, and calculate the estimated values of the Doppler center frequency and the Doppler frequency modulation according to the fitting result; A second calculation module is configured to calculate the product of the corrected signal and a preset azimuth frequency filter, and subject the calculation result to inverse Fourier transform, to obtain the imaging result of the spaceborne SAR moving target; wherein the azimuth frequency filter is established according to the azimuth frequency, the Doppler center frequency and the Doppler frequency modulation. The computer device comprises a memory and a processor, the memory is configured to store a computer program, and the processor is configured to execute the computer program stored on the memory, to realize the steps of the method of any one of claims 1-2.

4. A computer device, comprising: The storage medium stores a computer program, and the computer program is executed by the processor to realize the steps of the method of any one of claims 1-2.

5. A computer readable storage medium, characterized in that, ​ 6. A computer program product, characterised in that, A computer program comprising computer program elements which, when executed by a processor, implement the steps of the method according to any one of claims 1-2.

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