Method, device and medium for estimating range-varying phase error of synthetic aperture radar

Abstract

The present invention discloses a method, device and medium for estimating the distance space-variant phase error of a synthetic aperture radar. The method comprises: reading the original echo data of SAR and performing motion compensation and two-dimensional decoupling processing; performing distance dimension sampling on the processed data; performing secondary phase compensation and azimuth sub-aperture division on the sampled data; calculating the coherent cross-correlation function of each sub-aperture data; determining the estimated value of the range phase error parameter according to the coherent cross-correlation function, and updating the range phase error parameter according to the estimated value; determining the distance space-variant phase error function according to the finally determined range phase error parameter. The present invention can realize the accurate distance space-variant phase error estimation of the synthetic aperture radar with a small number of iterations, does not need to perform distance block processing on the original echo data, has strong applicability to different scenes, and is suitable for the implementation of real-time processing board as a key step in synthetic aperture radar imaging.

Description

Technical Field

[0001] The present invention relates to the technical field of synthetic aperture radar, and in particular to a method, device and medium for estimating a range space-varying phase error of a synthetic aperture radar. Background Art

[0002] During operation, Synthetic Aperture Radar (SAR) performs motion compensation on data through the platform motion parameters recorded by the position and attitude measurement unit. However, due to the accuracy of the position and attitude measurement unit, there is still a residual phase error after motion compensation, and this phase error is distance-variant, which will affect the azimuth focusing performance of the image.

[0003] To address this problem, current methods include distance-blocking combined with map-drift (MD), which requires distance-blocking processing of the original echo data, which requires a large amount of computation. In addition, such methods are based on sub-aperture non-correlated processing, and the estimation operation requires multiple iterations, resulting in poor convergence. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method, device and medium for estimating the range space-varying phase error of a synthetic aperture radar in view of the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides a method for estimating a range space-variant phase error of a synthetic aperture radar, comprising: reading original echo data of a synthetic aperture radar and performing motion compensation and two-dimensional decoupling processing to obtain first echo data; performing range dimension sampling processing on the first echo data to obtain second echo data; performing quadratic phase compensation on the second echo data using a quadratic phase compensation function to obtain third echo data; wherein the quadratic phase compensation function includes a range phase error parameter; performing azimuth sub-aperture division on the third echo data to obtain sub-aperture data, and calculating a coherent cross-correlation function of each sub-aperture data; determining an estimated value of the range phase error parameter according to the coherent cross-correlation function, and updating the range phase error parameter according to the estimated value; repeating quadratic phase compensation, azimuth sub-aperture division, coherent cross-correlation function calculation and range space-variant phase error parameter estimation until the estimated value of the range phase error parameter meets a preset accuracy; and determining a range space-variant phase error function according to the finally determined range phase error parameter.

[0006] In order to solve the above technical problems, the present invention also provides a distance-varying phase error estimation device for a synthetic aperture radar, comprising: a motion-compensated two-dimensional decoupling module, a distance-dimensional sampling module, a quadratic phase compensation module, a sub-aperture coherence cross-correlation determination module, a parameter updating module and a distance-varying phase error function determination module.

[0007] The motion compensation two-dimensional decoupling module is used to read the original echo data of the synthetic aperture radar and perform motion compensation and two-dimensional decoupling processing to obtain the first echo data.

[0008] The distance dimension sampling module is used to perform distance dimension sampling processing on the first echo data to obtain second echo data.

[0009] A secondary phase compensation module is used to perform secondary phase compensation on the second echo data using a secondary phase compensation function to obtain third echo data; wherein the secondary phase compensation function includes a range phase error parameter.

[0010] The sub-aperture coherent cross-correlation determination module is used to perform azimuth sub-aperture division on the third echo data to obtain sub-aperture data, and calculate the coherent cross-correlation function of each sub-aperture data.

[0011] A parameter updating module is used to determine the estimated value of the range phase error parameter according to the coherent mutual correlation function, and update the range phase error parameter according to the estimated value; repeatedly call the secondary phase compensation module and the sub-aperture coherent mutual coherence determination module until the estimated value of the range phase error parameter meets the preset accuracy.

[0012] The range space-variant phase error function determination module is used to determine the range space-variant phase error function according to the range phase error parameter finally determined.

[0013] In order to solve the above technical problems, the present invention also provides a range space-varying phase error estimation device for a synthetic aperture radar, comprising: a memory for storing a computer program; a processor for executing the computer program to implement the range space-varying phase error estimation method for a synthetic aperture radar as described in the above technical solution.

[0014] In order to solve the above technical problems, the present invention also provides a computer-readable storage medium, in which instructions are stored. When a computer reads the instructions, the computer executes the range-varying phase error estimation method of the synthetic aperture radar as described in the above technical solution.

[0015] The beneficial effects of the present invention are as follows: the present invention performs motion compensation and two-dimensional decoupling processing on original echo data; performs distance dimension sampling on the processed data; performs secondary phase compensation and azimuth sub-aperture division on the processed data; and then performs coherent cross-correlation function calculation, range phase error parameter estimation and range space-varying phase error function generation; the present invention can realize accurate range space-varying phase error estimation of synthetic aperture radar with a small number of iterations, does not need to perform range block processing on the original echo data, has a small amount of calculation and strong convergence; has strong applicability to different scenes, and as a key step in synthetic aperture radar imaging, is suitable for real-time processing board implementation.

[0016] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of a method for estimating a range-varying phase error of a synthetic aperture radar provided by an embodiment of the present invention;

[0018] Figure 2 A schematic diagram of a geometric model of a method for estimating a range-varying phase error of a synthetic aperture radar provided in an embodiment of the present invention;

[0019] Figure 3 A schematic diagram showing the comparison results of the target point azimuth impulse response curve of the synthetic aperture radar range space-varying phase error estimation method provided by the embodiment of the present invention and other existing methods;

[0020] Figure 4 A schematic diagram of the structural framework of a synthetic aperture radar range-varying phase error estimation device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0022] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein may be used to implement this device and / or practice this method.

[0023] Figure 1 A flow chart of a method for estimating a distance-varying phase error of a synthetic aperture radar provided by an embodiment of the present invention. The method for estimating a distance-varying phase error is applicable to a synthetic aperture radar and includes:

[0024] S1, reading the original echo data of the synthetic aperture radar SAR and performing motion compensation and two-dimensional decoupling processing to obtain the first echo data.

[0025] like Figure 2 As shown, the embodiment of the present invention is defined in rectangular coordinates O-XYZ, and the aircraft moves along the X-axis at a speed v. Affected by the motion error, the motion trajectory is a curve. p is a target point in the scene, and the horizontal coordinate of point p is x. The distance from the aircraft to the target point p is expressed as R p , the projection of this distance on the O-YZ plane is r.

[0026] The raw echo data of the synthetic aperture radar SAR read by the embodiment of the present invention can be expressed as:

[0027]

[0028] Where W(·) represents the window function, τ represents the distance to time, and T p Indicates pulse width, Δt=2R p / c represents the two-way delay of the electromagnetic wave from the radar to the target point p, R p represents the instantaneous slant distance from the radar to the target point p, c represents the speed of light, and f c represents the center frequency of the transmitted signal, and γ represents the signal modulation frequency.

[0029] After two-dimensional decoupling and motion compensation processing, the ideal signal can be expressed as:

[0030]

[0031] in,

[0032]

[0033] Where t represents the azimuth time, T a represents the synthetic aperture accumulation time, v represents the platform movement speed, x represents the azimuth coordinate of the target point p, r represents the slant range projection, and λ represents the wavelength.

[0034] Due to the limitation of position and attitude measurement accuracy, motion compensation cannot completely compensate for the phase error. The actual signal can be expressed as:

[0035]

[0036] Among them, a r represents the residual quadratic range-varying phase error parameter, a r =a l +b l ·r, a l represents the range-dependent non-space-varying phase error parameter after the lth iteration, b l It represents the range-dependent phase error parameter after the lth iteration, l = 0, 1, 2, 3...L, L represents the number of iterations

[0037] S2, performing distance dimension sampling processing on the first echo data to obtain second echo data.

[0038] S3, performing secondary phase compensation on the second echo data using a secondary phase compensation function to obtain third echo data; wherein the secondary phase compensation function includes a range phase error parameter.

[0039] S4, performing azimuth sub-aperture division on the third echo data to obtain sub-aperture data, and calculating a coherent cross-correlation function of each sub-aperture data.

[0040] S5, determining an estimated value of a range phase error parameter according to the coherent cross-correlation function.

[0041] S6, determine whether the estimated value of the range phase error parameter meets the preset accuracy. If not, update the range phase error parameter of the quadratic phase compensation function in S3 according to the estimated value, and repeat S3 to S5; if satisfied, execute S7.

[0042] S7, determining a range-variant phase error function according to the finally determined range phase error parameter.

[0043] The present invention implements the following steps: performing motion compensation and two-dimensional decoupling processing on original echo data; performing range dimension sampling on the processed data; performing secondary phase compensation and azimuth sub-aperture division on the processed data; and then performing coherent cross-correlation function calculation, range phase error parameter estimation, and range space-varying phase error function generation. The present invention can realize accurate range space-varying phase error estimation of synthetic aperture radar with a small number of iterations, does not need to perform range-varying block processing on the original echo data, has a small amount of calculation, and has strong convergence. The present invention has strong applicability to different scenes, and as a key step in synthetic aperture radar imaging, is suitable for real-time processing board implementation.

[0044] A range space-varying phase error estimation method provided by another embodiment of the present invention is applicable to a synthetic aperture radar, and includes:

[0045] S1, read the original echo data of the synthetic aperture radar SAR and perform motion compensation and two-dimensional decoupling processing to obtain the first echo data. Through this step of processing, the envelope error in the data is corrected, and only the phase error remains.

[0046] S2, performing distance dimension sampling processing on the first echo data to obtain second echo data.

[0047] It should be noted that the distance dimension sampling process for the first echo data may include the following steps:

[0048] S21, summing the absolute value of the first echo data in the azimuth direction to obtain the azimuth sum of the first echo data The formula is as follows:

[0049]

[0050] in, The first echo data The discretized representation form of the first echo data is M in the range direction and N in the azimuth direction. m is the range unit after the data is discretized, n is the azimuth unit after the data is discretized, ∑(·) represents the summation operation, and |·| represents the absolute value operation.

[0051] S22, the azimuth sum of the first echo data In the distance direction, it is divided into L blocks, where L is an integer greater than or equal to 4, and L is generally 4 to 8; In the range direction, the sampling range gates used for estimation can be distributed more evenly in the range direction to avoid the strong points being concentrated in a certain area, which affects the estimation accuracy of the range space-variant phase parameters.

[0052] S23, arranging each block of data in descending order, taking the data corresponding to the first K / L range units of each block of data to form a new block of data for estimation; K represents the number of sampled range gates;

[0053] S24, L blocks of new block data constitute the discretized second echo data The number of azimuth points of the second echo data is N, and the second echo data is represented by a continuous signal mode: m is the distance unit after data discretization, and n is the azimuth unit after data discretization.

[0054] S3, performing secondary phase compensation on the second echo data using a secondary phase compensation function to obtain third echo data; wherein the secondary phase compensation function includes a range phase error parameter;

[0055] S4, performing azimuth sub-aperture division on the third echo data to obtain sub-aperture data, and calculating a coherent cross-correlation function of each sub-aperture data.

[0056] S5, determining an estimated value of a range phase error parameter according to the coherent cross-correlation function.

[0057] S6, determine whether the estimated value of the range phase error parameter meets the preset accuracy. If not, update the range phase error parameter of the quadratic phase compensation function in S3 according to the estimated value, and repeat S3 to S5; if satisfied, execute S7.

[0058] S7, determining a range-variant phase error function according to the finally determined range phase error parameter.

[0059] The embodiment of the present invention divides the azimuth sum of the first echo data into blocks in the range direction, so that the sampling range gates used for estimation can be distributed more evenly in the range direction, thereby avoiding that strong points are concentrated in a certain area and affecting the estimation accuracy of the range space-varying phase parameter.

[0060] A distance space-varying phase error estimation method provided by another embodiment of the present invention is applicable to a synthetic aperture radar, and includes:

[0061] S1, reading the original echo data of the synthetic aperture radar SAR and performing motion compensation and two-dimensional decoupling processing to obtain the first echo data.

[0062] S2, performing distance dimension sampling processing on the first echo data to obtain second echo data.

[0063] It should be noted that the distance dimension sampling process for the first echo data may include the following steps:

[0064] S21, summing the absolute value of the first echo data in the azimuth direction to obtain the azimuth sum of the first echo data The formula is as follows:

[0065]

[0066] in, The first echo data The discretized representation form of the first echo data is M in the range direction and N in the azimuth direction. m is the range unit after the data is discretized, n is the azimuth unit after the data is discretized, ∑(·) represents the summation operation, and |·| represents the absolute value operation.

[0067] S22, the azimuth sum of the first echo data In the distance direction, it is divided into L blocks, where L is an integer greater than or equal to 4, and L is generally 4 to 8; In the range direction, the sampling range gates used for estimation can be distributed more evenly in the range direction to avoid the strong points being concentrated in a certain area, which affects the estimation accuracy of the range space-variant phase parameters.

[0068] S23, arranging each block of data in descending order, taking data corresponding to the first K / L distance units of each block of data to form new block data for estimation;

[0069] S24, L blocks of new block data constitute the discretized second echo data The number of points in the range direction of the second echo data is K, the number of points in the azimuth direction is N, and the second echo data is represented by a continuous signal mode: m is the distance unit after data discretization, and n is the azimuth unit after data discretization.

[0070] S3, performing secondary phase compensation on the second echo data using a secondary phase compensation function to obtain third echo data; wherein the secondary phase compensation function includes a range phase error parameter;

[0071] It should be noted that the second echo data is subjected to secondary phase compensation, and the secondary phase compensation function h(t) is:

[0072]

[0073] The specific operation is to combine h(t) with Multiplication:

[0074]

[0075] in, is the third echo data, h(t) is the quadratic phase compensation function, j represents the imaginary unit, λ represents the wavelength, v represents the platform movement speed, t represents the azimuth time, x represents the azimuth coordinate of the target point p, r represents the slant range projection, and the range phase error parameters include a l and b l , a l represents the range-dependent non-space-varying phase error parameter after the lth iteration, b l It represents the range-dependent space-variant phase error parameter after the lth iteration, l=0, 1, 2, 3...L, where L represents the number of iterations.

[0076] S4, performing azimuth sub-aperture division on the third echo data to obtain sub-aperture data, and calculating a coherent cross-correlation function of each sub-aperture data;

[0077] For the third echo data It is divided into two sub-apertures in azimuth direction. The sizes of the two sub-apertures are the same, which are expressed as:

[0078]

[0079]

[0080] a r =a l +b l ·r

[0081] Among them, a r Represents the range phase error parameter. In the first calculation, for the above a l and b l Two parameters are initialized: a0=0, b0=0.

[0082] The first sub-aperture data and the second subaperture data Perform azimuth Fourier transform to obtain the spectrum function of the first sub-aperture data. and the spectral function of the second sub-aperture data

[0083]

[0084]

[0085] in, represents the convolution operator, w represents the azimuthal spectrum, and h(w) is expressed as:

[0086]

[0087]

[0088] Here, ∫(·) represents an integral operator.

[0089] The coherent cross-correlation function can be obtained by the following calculation:

[0090]

[0091] Among them, R CMD (η) is the coherent cross-correlation function, T a represents the synthetic aperture time, η represents the abscissa of the coherent cross-correlation function, and * represents the conjugate sign.

[0092] S5, determining an estimated value of a range phase error parameter according to the coherent cross-correlation function.

[0093] Specifically, the coherent cross-correlation function R CMD (η) takes the maximum value and obtains the maximum position function

[0094]

[0095] Here, max|·| represents the maximum value operation of the modulus.

[0096] The estimated value of the range phase error parameter is determined according to the following formula: and

[0097]

[0098]

[0099] in, represents the estimated value of the range-dependent non-space-varying phase error parameter, represents the estimated value of the range-to-space phase error parameter, K represents the number of sampled range gates, i represents the sampled range gate sequence number, express The mean value, r i represents the actual distance corresponding to the i-th range gate, Represents r i The mean of .

[0100] S6, determine whether the estimated value of the range phase error parameter meets the preset accuracy. If not, update the range phase error parameter of the quadratic phase compensation function in S3 according to the estimated value, and repeat S3 to S5; if satisfied, execute S7.

[0101] Specifically, the range phase error parameter is updated according to the estimated value, and the formula is as follows:

[0102]

[0103] in, represents the estimated value of the range-dependent non-space-varying phase error parameter, represents the estimated value of the range-dependent phase error parameter, a l represents the range-dependent non-space-varying phase error parameter after the lth iteration, a l+1 represents the range-dependent non-space-varying phase error parameter after the l+1th iteration, b l represents the range-to-space phase error parameter after the lth iteration, b l+1 represents the range-dependent space-variable phase error parameter after the l+1th iteration, l=0, 1, 2, 3...L, L represents the number of iterations

[0104] When the following conditions are met It is determined that the estimated value of the range phase error parameter meets the preset accuracy.

[0105] S7, determining a range-variant phase error function according to the finally determined range phase error parameter.

[0106] Φ(t)=exp[-j(a l +b l ·r)t 2 ].

[0107] The embodiment of the present invention can realize accurate distance space-varying phase error estimation of synthetic aperture radar with a small number of iterations, does not need to perform range-wise block processing on the original echo data, has strong applicability to different scenarios, and is suitable for real-time processing board implementation as a key step in synthetic aperture radar imaging.

[0108] The following is a simulation verification of the synthetic aperture radar range space-varying phase error estimation method proposed in the embodiment of the present invention. The measured data can be processed by software such as Matlab. The experimental parameters are shown in Table 1. The motion error compensation and imaging processing are performed by the synthetic aperture radar range space-varying phase error estimation method proposed in the present invention. The comparison results of the azimuth impulse response curve obtained by the fixed calibration point in the scene and the existing method are shown in Figure 3 As shown in FIG. 1 , the comparison method 1 uses a non-coherent space-variant phase estimation method. The comparison method 2 uses a non-space-variant phase estimation method.

[0109] Depend on Figure 3 It can be clearly seen that the residual space-variant phase error of the method of comparison method 2 has a greater impact on the imaging effect. The imaging effect of the estimation method provided by the embodiment of the present invention is better than that of comparison method 1; the number of iterations is less than that of comparison method 1. In the comparison experiment, this method can converge with only one iteration, while method 1 requires more than two iterations to converge.

[0110] Table 1

[0111] parameter result Working band Ka Resolution 0.3m

[0112] It can be understood that in some embodiments, some or all of the optional implementation modes in the above embodiments may be included.

[0113] The embodiment of the present invention provides a distance space-varying phase error estimation device for a synthetic aperture radar, comprising: a motion compensated two-dimensional decoupling module, a distance dimension sampling module, a quadratic phase compensation module, a sub-aperture coherence cross-correlation determination module, a parameter updating module and a distance space-varying phase error function determination module.

[0114] The motion compensation two-dimensional decoupling module is used to read the original echo data of the synthetic aperture radar and perform motion compensation and two-dimensional decoupling processing to obtain the first echo data.

[0115] The distance dimension sampling module is used to perform distance dimension sampling processing on the first echo data to obtain second echo data.

[0116] A secondary phase compensation module is used to perform secondary phase compensation on the second echo data using a secondary phase compensation function to obtain third echo data; wherein the secondary phase compensation function includes a range phase error parameter.

[0117] The sub-aperture coherent cross-correlation determination module is used to perform azimuth sub-aperture division on the third echo data to obtain sub-aperture data, and calculate the coherent cross-correlation function of each sub-aperture data.

[0118] A parameter updating module is used to determine the estimated value of the range phase error parameter according to the coherent mutual correlation function, and update the range phase error parameter according to the estimated value; repeatedly call the secondary phase compensation module and the sub-aperture coherent mutual coherence determination module until the estimated value of the range phase error parameter meets the preset accuracy.

[0119] The range space-variant phase error function determination module is used to determine the range space-variant phase error function according to the range phase error parameter finally determined.

[0120] The present invention also provides a storage medium, in which instructions are stored. When a computer reads the instructions, the computer executes the method for estimating the range-varying phase error of a synthetic aperture radar in any of the above embodiments.

[0121] like Figure 4 As shown, the present invention also provides a synthetic aperture radar range space-varying phase error estimation device, comprising:

[0122] Memory 1, used for storing computer programs;

[0123] Processor 2 is used to execute a computer program to implement the synthetic aperture radar range space-varying phase error estimation method as described in any of the above embodiments.

[0124] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0125] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0126] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0127] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0128] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0129] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for estimating range-varying phase error of synthetic aperture radar, characterized in that: include: Reading the original echo data of the synthetic aperture radar and performing motion compensation and two-dimensional decoupling processing to obtain the first echo data; Performing distance dimension sampling processing on the first echo data to obtain second echo data; Performing secondary phase compensation on the second echo data using a secondary phase compensation function to obtain third echo data; wherein the secondary phase compensation function includes a range phase error parameter; Performing azimuth sub-aperture division on the third echo data to obtain sub-aperture data, and calculating a coherent cross-correlation function of each sub-aperture data; Determine an estimated value of the range phase error parameter according to the coherent cross-correlation function, and update the range phase error parameter according to the estimated value; Repeating the secondary phase compensation, azimuth sub-aperture division, coherent cross-correlation function calculation and range space-variant phase error parameter estimation until the estimated value of the range phase error parameter meets the preset accuracy; A range-variant phase error function is determined according to the range-dependent phase error parameter finally determined.

2. The method according to claim 1, characterized in that The performing distance dimension sampling processing on the first echo data to obtain second echo data includes: summing the absolute values ​​of the first echo data in the azimuth direction to obtain the azimuth sum of the first echo data; The azimuth sum of the first echo data is divided into L blocks in the range direction, where L is an integer greater than or equal to 4; Arrange each block of data in descending order, and take the data corresponding to the first K / L range units in each block to form a new block of data; K represents the number of sampled range gates; L blocks of new block data constitute the discretized second echo data The number of azimuth points of the second echo data is N, m is the range unit after the data is discretized, and n is the azimuth unit after the data is discretized.

3. The method according to claim 1, characterized in that The second echo data is subjected to secondary phase compensation using a secondary phase compensation function to obtain third echo data. The calculation formula is as follows: in, is the third echo data, is the continuous signal representation of the second echo data, h(t) is the quadratic phase compensation function, j represents the imaginary unit, λ represents the wavelength, v represents the platform movement speed, t represents the azimuth time, x represents the azimuth coordinate of the target point p, r represents the slant range projection, and the range phase error parameters include a l and b l , a l represents the range-dependent non-space-varying phase error parameter after the lth iteration, b l It represents the range-dependent space-variant phase error parameter after the lth iteration, l=0, 1, 2, 3...L, where L represents the number of iterations.

4. The method according to claim 3, characterized in that The step of performing azimuth sub-aperture division on the third echo data to obtain sub-aperture data and calculating the coherent cross-correlation function of each sub-aperture data includes: The third echo data In the azimuth direction, it is divided into two sub-apertures of the same size, represented as the first sub-aperture data and the second subaperture data The first sub-aperture data and the second subaperture data Perform azimuth Fourier transform to obtain the spectrum function of the first sub-aperture data. and the spectral function of the second sub-aperture data w represents the azimuthal spectrum; The coherent cross-correlation function of each sub-aperture data is as follows: Among them, R CMD (η) is the coherent cross-correlation function, T a represents the synthetic aperture time, η represents the abscissa of the coherent cross-correlation function, and * represents the conjugate sign.

5. The method according to claim 4, characterized in that The step of determining the estimated value of the range phase error parameter according to the coherent cross-correlation function comprises: The coherent cross-correlation function R CMD (η) takes the maximum value and obtains the maximum position function The estimated value of the range phase error parameter is determined according to the following formula: and in, represents the estimated value of the range-dependent non-space-varying phase error parameter, represents the estimated value of the range-to-space phase error parameter, K represents the number of sampled range gates, i represents the sampled range gate number, express The mean value, r i represents the actual distance corresponding to the i-th range gate, Represents r i The mean of .

6. The method according to claim 5, characterized in that The range phase error parameter is updated according to the estimated value, and the formula is as follows: Among them, a l represents the range-dependent non-space-varying phase error parameter after the lth iteration, a l+1 represents the range-dependent non-space-varying phase error parameter after the l+1th iteration, b l represents the range-to-space phase error parameter after the lth iteration, b l+1 It represents the range-dependent space-variant phase error parameter after the l+1th iteration, l=0, 1, 2, 3...L, and L represents the number of iterations.

7. The method according to any one of claims 1 to 6, characterized in that: The range-variant phase error function is determined according to the range-dependent phase error parameter finally determined, and the formula is as follows: Φ(t)=exp[-j(a l +b l ·r)t 2 ]; Among them, a l represents the range-dependent non-space-varying phase error parameter after the lth iteration, b l It represents the range-dependent space-variant phase error parameter after the lth iteration, l=0, 1, 2, 3...L, L represents the number of iterations, and r represents the slant range projection.

8. A range-varying phase error estimation device for a synthetic aperture radar, characterized in that: include: A motion compensation two-dimensional decoupling module is used to read the original echo data of the synthetic aperture radar and perform motion compensation and two-dimensional decoupling processing to obtain the first echo data; A distance dimension sampling module, used for performing distance dimension sampling processing on the first echo data to obtain second echo data; A secondary phase compensation module, used for performing secondary phase compensation on the second echo data using a secondary phase compensation function to obtain third echo data; wherein the secondary phase compensation function includes a range phase error parameter; A sub-aperture coherent cross-correlation determination module, configured to perform azimuth sub-aperture division on the third echo data to obtain sub-aperture data, and calculate a coherent cross-correlation function of each sub-aperture data; A parameter updating module, used to determine an estimated value of the range phase error parameter according to the coherent cross-correlation function, and update the range phase error parameter according to the estimated value; Repeatedly calling the secondary phase compensation module and the sub-aperture coherence and mutual coherence determination module until the estimated value of the range phase error parameter meets the preset accuracy; The range space-variant phase error function determination module is used to determine the range space-variant phase error function according to the range phase error parameter finally determined.

9. A range-varying phase error estimation device for a synthetic aperture radar, characterized in that: include: Memory for storing computer programs; A processor, configured to execute the computer program to implement the range-varying phase error estimation method for a synthetic aperture radar according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The storage medium stores instructions, and when a computer reads the instructions, the computer executes the range-varying phase error estimation method for a synthetic aperture radar according to any one of claims 1 to 7.

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