A method and system for rapid imaging of video synthetic aperture radar

Abstract

The invention discloses a method and system for rapid imaging of video synthetic aperture radar, and relates to the field of synthetic aperture radar. The method comprises: reading video SAR echo data and auxiliary data, calculating sub-aperture length according to the auxiliary data, performing sub-aperture block division on the video SAR echo data according to the sub-aperture length, obtaining video SAR echo data after block division, performing sub-aperture imaging on the video SAR echo data after block division, obtaining sub-aperture imaging results of each frame, performing weighted superposition on sub-aperture imaging results of each frame according to multiple constructed sub-aperture weighting coefficient factors to obtain multiple frames of images, generating radar image video streams according to the multiple frames of images, being able to realize rapid imaging of video synthetic aperture radar, outputting continuous video streams, having strong practicability, being applicable to various complex scenes, being a key step in video synthetic aperture radar imaging, and being applicable to real-time processing board implementation.

Description

Technical Field

[0001] The invention relates to the field of synthetic aperture radar, and in particular to a method and system for rapid imaging of a video synthetic aperture radar. Background Art

[0002] Video Synthetic Aperture Radar (SAR) achieves continuous observation of a fixed area by controlling the beam pointing during operation, ultimately forming a video stream. During the imaging process, due to the high degree of overlap of multiple frames of image data at high frame rates, traditional imaging methods process each frame of the image relatively independently, which greatly increases the amount of computation required for imaging processing.

[0003] To address this issue, there are many research results on rapid imaging methods, most of which are based on rapid imaging within a single frame image, and there is still a lack of video SAR rapid imaging methods under high frame rate conditions. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method and system for rapid imaging of a video synthetic aperture radar in view of the deficiencies of the prior art.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] A method for rapid imaging of a video synthetic aperture radar, comprising:

[0007] Read video SAR echo data and auxiliary data;

[0008] Calculating a sub-aperture length according to the auxiliary data, performing sub-aperture block division on the video SAR echo data according to the sub-aperture length, and obtaining the divided video SAR echo data;

[0009] Performing sub-aperture imaging on the divided video SAR echo data to obtain sub-aperture imaging results for each frame;

[0010] According to the constructed multiple sub-aperture weighting coefficient factors, weighted superposition is performed on each frame of sub-aperture imaging results to obtain multiple frames of images, and a radar image video stream is generated according to the multiple frames of images.

[0011] The beneficial effects of the present invention are as follows: the scheme is video SAR fast imaging under high frame rate conditions, and the video synthetic aperture radar fast imaging method provided by the present invention reads video SAR echo data and auxiliary data; constructs an imaging coordinate system according to an observation scene; performs sub-aperture blocking on original echo data; performs sub-aperture imaging on the blocked data; constructs sub-aperture weighting coefficient factors; performs weighted superposition on sub-aperture images for each frame; generates a radar image video stream, can realize video synthetic aperture radar fast imaging, output a continuous video stream, has strong practicability, is applicable to various complex scenes, and is applicable to real-time processing board implementation as a key step in video synthetic aperture radar imaging.

[0012] Furthermore, constructing multiple sub-aperture weighting coefficient factors specifically includes:

[0013] Construct a weighted window function;

[0014] The weighted window function is divided into multiple segments, and a quadratic polynomial is fitted to each segment of the weighted window function data to obtain multiple sub-aperture weighting coefficient factors; wherein the multiple sub-aperture weighting coefficient factors include: a constant term parameter C(g), a linear term parameter L(g), and a quadratic term parameter Q(g).

[0015] Furthermore, the step of performing weighted superposition on each frame of sub-aperture imaging results according to the constructed multiple sub-aperture weighting coefficient factors to obtain multiple frames of images specifically includes:

[0016] The multiple frames of images are calculated according to the first formula, wherein the first formula is:

[0017] I i =I c g+i-1 ·C(g)+I L g+i-1 ·L(g)+I Q g+i-1 Q(g),

[0018] Where i represents the serial number of the image frame, C(g) represents the constant term parameter, L(g) represents the linear term parameter, and Q(g) represents the quadratic term parameter. and It represents the three groups of imaging results of each sub-aperture, and the superscript g+i-1 represents the g+i-1th sub-aperture.

[0019] Further, performing sub-aperture imaging on the divided video SAR echo data to obtain sub-aperture imaging results for each frame specifically includes:

[0020] Transform the latitude sequence, longitude sequence and altitude sequence of the payload platform into the Earth-centered Earth-fixed coordinate system to obtain the first coordinate in the Earth-centered Earth-fixed coordinate system;

[0021] According to the first coordinate of the payload platform in the earth-centered earth-fixed coordinate system and the second coordinate of the imaging grid point in the earth-centered earth-fixed coordinate system, a slant distance between the first coordinate and the second coordinate at each pulse time is obtained;

[0022] According to the slant distance, a back-projection imaging algorithm is used to image each sub-aperture within an imaging grid to obtain sub-aperture imaging results for each frame.

[0023] Further, the auxiliary data includes: radar system parameters, payload platform motion parameters, imaging grid parameters and video frame frequency;

[0024] The calculating the sub-aperture length according to the auxiliary data specifically includes:

[0025] The sub-aperture length is calculated according to the pulse repetition frequency in the auxiliary data and the frame frequency of the image of the video stream to be output.

[0026] Another technical solution of the present invention to solve the above technical problems is as follows:

[0027] A video synthetic aperture radar rapid imaging system, comprising: a radar data reading module, a sub-aperture blocking module, an imaging module and a video stream generating module;

[0028] The radar data reading module is used to read video SAR echo data and auxiliary data;

[0029] The sub-aperture blocking module is used to calculate the sub-aperture length according to the auxiliary data, and perform sub-aperture blocking on the video SAR echo data according to the sub-aperture length to obtain the blocked video SAR echo data;

[0030] The imaging module is used to perform sub-aperture imaging on the divided video SAR echo data to obtain sub-aperture imaging results for each frame;

[0031] The video stream generation module is used to perform weighted superposition on each frame of sub-aperture imaging results according to the constructed multiple sub-aperture weighting coefficient factors to obtain multiple frames of images, and generate a radar image video stream according to the multiple frames of images.

[0032] The beneficial effects of the present invention are as follows: the scheme is video SAR fast imaging under high frame rate conditions, and the video synthetic aperture radar fast imaging method provided by the present invention reads video SAR echo data and auxiliary data; constructs an imaging coordinate system according to an observation scene; performs sub-aperture blocking on original echo data; performs sub-aperture imaging on the blocked data; constructs sub-aperture weighting coefficient factors; performs weighted superposition on sub-aperture images for each frame; generates a radar image video stream, can realize video synthetic aperture radar fast imaging, output a continuous video stream, has strong practicability, is applicable to various complex scenes, and is applicable to real-time processing board implementation as a key step in video synthetic aperture radar imaging.

[0033] Furthermore, it also includes: a weighting factor construction module for constructing a weighted window function;

[0034] The weighted window function is divided into multiple segments, and a quadratic polynomial is fitted to each segment of the weighted window function data to obtain multiple sub-aperture weighting coefficient factors; wherein the multiple sub-aperture weighting coefficient factors include: a constant term parameter C(g), a linear term parameter L(g), and a quadratic term parameter Q(g).

[0035] Furthermore, the video stream generation module is specifically used to calculate multiple frames of images according to a first formula, wherein the first formula is:

[0036] I i =I c g+i-1 ·C(g)+I L g+i-1 ·L(g)+I Q g+i-1 Q(g),

[0037] Where i represents the serial number of the image frame, C(g) represents the constant term parameter, L(g) represents the linear term parameter, and Q(g) represents the quadratic term parameter. and It represents the three groups of imaging results of each sub-aperture, and the superscript g+i-1 represents the g+i-1th sub-aperture.

[0038] Furthermore, the imaging module is specifically used to transform the latitude sequence, longitude sequence and altitude sequence of the payload platform into an earth-centered earth-fixed coordinate system to obtain a first coordinate in the earth-centered earth-fixed coordinate system;

[0039] According to the first coordinate of the payload platform in the earth-centered earth-fixed coordinate system and the second coordinate of the imaging grid point in the earth-centered earth-fixed coordinate system, a slant distance between the first coordinate and the second coordinate at each pulse time is obtained;

[0040] According to the slant distance, a back-projection imaging algorithm is used to image each sub-aperture within an imaging grid to obtain sub-aperture imaging results for each frame.

[0041] Further, the auxiliary data includes: radar system parameters, payload platform motion parameters, imaging grid parameters and video frame frequency;

[0042] The sub-aperture blocking module is specifically used to calculate the sub-aperture length according to the pulse repetition frequency in the auxiliary data and the frame frequency of the image of the video stream to be output.

[0043] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic flow chart of a method for rapid imaging of a video synthetic aperture radar provided by an embodiment of the present invention;

[0045] Figure 2 A structural block diagram of a video synthetic aperture radar rapid imaging system provided by an embodiment of the present invention;

[0046] Figure 3 A schematic flow chart of a video synthetic aperture radar rapid imaging method provided by other embodiments of the present invention;

[0047] Figure 4 A schematic diagram of point target simulation imaging results provided by other embodiments of the present invention;

[0048] Figure 5 A schematic diagram of a point target azimuth impulse response curve provided by other embodiments of the present invention;

[0049] Figure 6 A schematic diagram of imaging results of measured data provided by other embodiments of the present invention. DETAILED DESCRIPTION

[0050] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention but not to limit the scope of the present invention.

[0051] like Figure 1 As shown, a method for rapid imaging of a video synthetic aperture radar provided by an embodiment of the present invention includes:

[0052] S1, read the video SAR echo data and auxiliary data; wherein, the read video SAR echo data is the radar echo data S after range pulse compression, and the auxiliary data includes radar system parameters, payload platform motion parameters, imaging grid parameters, and video frame frequency.

[0053] Among them, the radar system parameters include sampling rate Fs, pulse repetition frequency PRF, center frequency f c ; The load platform motion parameters include the load platform latitude sequence P Lat , longitude sequence P Lon , height sequence P H ; The imaging grid parameters include the latitude C of the scene center Lat , longitude C Lon , height C H , grid spacing Δd, number of scene points M×N; video frame frequency is the frame frequency FR of the image to be output video stream.

[0054] S2, calculating the sub-aperture length according to the auxiliary data, performing sub-aperture block division on the video SAR echo data according to the sub-aperture length, and obtaining the divided video SAR echo data; wherein the sub-aperture length is: the product of the frame frequency FR of the image and the PRF. In this way, the data is further divided, and each sub-aperture has the same length and is arranged in sequence to form full-aperture data.

[0055] It should be noted that, in a certain embodiment, the sub-aperture length N a The choice of (subaperture length is the number of subaperture points) is calculated according to the following formula:

[0056] N a =FR·PRF,

[0057] Wherein, FR is the video frame frequency, which is the frame frequency of the image of the video stream to be output; PRF is the pulse repetition frequency.

[0058] S3, performing sub-aperture imaging on the divided video SAR echo data to obtain sub-aperture imaging results for each frame; the divided video SAR echo data represents sub-aperture video SAR echo data.

[0059] It should be noted that, in a certain embodiment, the sub-aperture imaging process, using sub-aperture data for imaging processing, may include:

[0060] For the latitude sequence P of the load platform Lat , longitude sequence P Lon , height sequence P H Transformed to the Earth-centered Earth-fixed coordinate system, it is expressed as (P ECEF-X ,P ECEF-Y ,P ECEF-Z ). According to the coordinates of the load platform in the Earth-centered Earth-fixed coordinate system (P ECEF-X ,P ECEF-Y ,P ECEF-Z ) and the coordinates of the imaging grid points in the Earth-centered Earth-fixed coordinate system (I ECEF-X ,I ECEF-Y,I ECEF-Z ), and solve for each pulse time to obtain the slant distance R(k,m,n) from the load platform at time k to the imaging grid coordinate (m,n):

[0061]

[0062] According to the slant distance calculated above, the back-projection imaging algorithm is used to image each sub-aperture in the imaging grid, and the three-group imaging results of each sub-aperture are expressed as I C g ,I L g and I Q g , where the superscript g represents the g-th subaperture, and the calculation methods are:

[0063]

[0064]

[0065]

[0066] S4, performing weighted superposition on each frame of sub-aperture imaging results to obtain multiple frames of images according to the constructed multiple sub-aperture weighting coefficient factors, and generating a radar image video stream according to the multiple frames of images. The multiple sub-aperture weighting coefficient factors may include: a constant term parameter C(g), a linear term parameter L(g), and a quadratic term parameter Q(g).

[0067] It should be noted that, in a certain embodiment, the radar image video stream generation process may include:

[0068] The single frame image I can be obtained by the following calculation:

[0069] I=I c g ·C(g)+I L g ·L(g)+I Q g Q(g),

[0070] For multi-frame image generation, the following expression is used:

[0071] I i =I c g+i-1 ·C(g)+I L g+i-1 ·L(g)+I Q g+i-1 Q(g),

[0072] Among them, i represents the serial number of the image frame, each frame i contains several images of sub-aperture g, i represents the i-th frame, and multiple frames of images can be obtained through the above calculation, and the image video stream is finally generated through the multiple frames of images.

[0073] The scheme is a video SAR fast imaging under high frame rate conditions. The video synthetic aperture radar fast imaging method provided by the present invention reads video SAR echo data and auxiliary data; constructs an imaging coordinate system according to an observation scene; performs sub-aperture blocking on the original echo data; performs sub-aperture imaging on the blocked data; constructs sub-aperture weighting coefficient factors; performs weighted superposition on the sub-aperture images for each frame; generates a radar image video stream, which can realize video synthetic aperture radar fast imaging and output a continuous video stream. The method has strong practicality and is applicable to various complex scenes. As a key step in video synthetic aperture radar imaging, the method is applicable to real-time processing board implementation.

[0074] Optionally, in any of the above embodiments, constructing a plurality of sub-aperture weighting coefficient factors specifically includes:

[0075] Construct a weighted window function;

[0076] The weighted window function is divided into multiple segments, and a quadratic polynomial is fitted to each segment of the weighted window function data to obtain multiple sub-aperture weighting coefficient factors; wherein the multiple sub-aperture weighting coefficient factors include: a constant term parameter C(g), a linear term parameter L(g), and a quadratic term parameter Q(g).

[0077] Optionally, in any of the above embodiments, performing weighted superposition on each frame of sub-aperture imaging results to obtain multiple frames of images according to the constructed multiple sub-aperture weighting coefficient factors specifically includes:

[0078] The multiple frames of images are calculated according to the first formula, wherein the first formula is:

[0079] I i =I c g+i-1 ·C(g)+I L g+i-1 ·L(g)+I Q g+i-1 Q(g),

[0080] Where i represents the serial number of the image frame, C(g) represents the constant term parameter, L(g) represents the linear term parameter, and Q(g) represents the quadratic term parameter. and It represents the three groups of imaging results of each sub-aperture, and the superscript g+i-1 represents the g+i-1th sub-aperture.

[0081] Optionally, in any of the above embodiments, performing sub-aperture imaging on the divided video SAR echo data to obtain a sub-aperture imaging result for each frame specifically includes:

[0082] Transform the latitude sequence, longitude sequence and altitude sequence of the payload platform into the Earth-centered Earth-fixed coordinate system to obtain the first coordinate in the Earth-centered Earth-fixed coordinate system;

[0083] According to the first coordinate of the payload platform in the earth-centered earth-fixed coordinate system and the second coordinate of the imaging grid point in the earth-centered earth-fixed coordinate system, the slant distance between the first coordinate and the second coordinate at each pulse time is obtained; wherein the first coordinate can be the coordinate of the payload platform in the earth-centered earth-fixed coordinate system (P ECEF-X ,P ECEF-Y ,P ECEF-Z ); The second coordinate may be the coordinate of the imaging grid point in the Earth-centered Earth-fixed coordinate system (I ECEF-X ,I ECEF-Y ,I ECEF-Z );

[0084] It should be noted that the calculation of the slant distance between the first coordinate and the second coordinate may include:

[0085] The slant distance R(k,m,n) from the load platform to the imaging grid coordinate (m,n) at time k is:

[0086]

[0087] According to the slant distance, a back-projection imaging algorithm is used to image each sub-aperture within an imaging grid to obtain sub-aperture imaging results for each frame.

[0088] Optionally, in any of the above embodiments, the auxiliary data includes: radar system parameters, payload platform motion parameters, imaging grid parameters and video frame frequency;

[0089] The calculating the sub-aperture length according to the auxiliary data specifically includes:

[0090] The sub-aperture length is calculated according to the pulse repetition frequency in the auxiliary data and the frame frequency of the image of the video stream to be output.

[0091] In one embodiment, if Figure 3 As shown, an embodiment of a video synthetic aperture radar rapid imaging method provides a flow chart, and the rapid imaging method is applicable to a video synthetic aperture radar, comprising:

[0092] S11, reading video SAR echo data and auxiliary data;

[0093] It should be noted that the video SAR echo data read is the radar echo data S after range pulse compression, and the auxiliary data includes radar system parameters, payload platform motion parameters, imaging grid parameters, and video frame frequency.

[0094] Among them, the radar system parameters include sampling rate Fs, pulse repetition frequency PRF, center frequency f c ; The load platform motion parameters include the load platform latitude sequence P Lat , longitude sequence P Lon , height sequence P H ; The imaging grid parameters include the latitude C of the scene center Lat , longitude C Lon , height C H , grid spacing Δd, number of scene points M×N; video frame frequency is the frame frequency FR of the image to be output video stream.

[0095] S12, constructing an imaging coordinate system according to the observation scene;

[0096] It should be noted that the imaging grid matrix I is constructed M×N , the spacing between each grid point is Δd, then for the grid points with coordinates (m,n) in the grid, their coordinate values ​​are:

[0097]

[0098]

[0099] I z (m,n)=C H

[0100] Set the latitude C of the scene center Lat , longitude C Lon , height C H Transformed to the Earth-centered Earth-fixed coordinate system, it is expressed as (C X ,C Y ,C Z ) Calculate the coordinates of each imaging grid point in the Earth-centered Earth-fixed coordinate system, and the coordinates are expressed as (I ECEF-X ,I ECEF-Y ,I ECEF-Z ). The calculation expression is:

[0101]

[0102] S13, performing sub-aperture partitioning on the original echo data;

[0103] It should be noted that the subaperture length N a The choice is calculated according to the following formula:

[0104] Na =FR·PRF

[0105] S14, performing sub-aperture imaging on the divided data;

[0106] It should be noted that for the latitude sequence P of the load platform Lat , longitude sequence P Lon , height sequence P H Transformed to the Earth-centered Earth-fixed coordinate system, it is expressed as (P ECEF-X ,P ECEF-Y ,P ECEF-Z ). According to the coordinates of the load platform in the Earth-centered Earth-fixed coordinate system (P ECEF-X ,P ECEF-Y ,P ECEF-Z ) and the coordinates of the imaging grid points in the Earth-centered Earth-fixed coordinate system (I ECEF-X ,I ECEF-Y ,I ECEF-Z ), and solve for each pulse time to obtain the slant distance R(k,m,n) from the load platform at time k to the imaging grid coordinate (m,n):

[0107]

[0108] According to the slant distance calculated above, the back-projection imaging algorithm is used to image each sub-aperture in the imaging grid, and the three-group imaging results of each sub-aperture are expressed as I C g ,I L g and I Q g , where the superscript g represents the g-th subaperture, and the calculation methods are:

[0109]

[0110]

[0111]

[0112] S15, constructing sub-aperture weighting coefficient factors;

[0113] It should be noted that the weighted window function w is constructed, taking the Hamming window as an example:

[0114]

[0115] Among them, M a is the number of full-aperture pulses accumulated for imaging.

[0116] The window function w is divided into G segments, where G represents the number of sub-apertures used for accumulation, and the number of pulses in each sub-aperture is N.a A quadratic polynomial is fitted for each segment of data, and the constant term parameter is C(g), the linear term parameter is L(g), and the quadratic term parameter is Q(g). The above parameters are sub-aperture weighting coefficient factors.

[0117] S16, performing weighted superposition on the sub-aperture images for each frame;

[0118] It should be noted that the single frame image I can be obtained by the following calculation:

[0119] I=I c g ·C(g)+I L g ·L(g)+I Q g Q(g)

[0120] S17, generating a radar image video stream.

[0121] It should be noted that for multi-frame image generation, the following expression is used:

[0122] I i =I c g+i-1 ·C(g)+I L g+i-1 ·L(g)+I Q g+i-1 Q(g)

[0123] Among them, i represents the serial number of the image frame. Through the above calculation, multiple frames of images can be obtained, and the image video stream is finally generated through the multiple frames of images.

[0124] In another embodiment, the video synthetic aperture radar rapid imaging method proposed in the present invention is simulated and verified, and point target simulation processing can be performed by software such as Matlab, and the experimental parameters are shown in Table 1. The point target simulation imaging results are shown in Table 1. Figure 4 As shown in the figure, the azimuth pulse response curve of the point target is as follows: Figure 5 shown.

[0125]

[0126]

[0127] Table 1

[0128] The video synthetic aperture radar fast imaging method proposed in the present invention is verified by actual data processing. The actual data processing can be performed by software such as Matlab. The experimental parameters are shown in Table 2. The imaging results of the actual data are shown in Table 2. Figure 6 shown.

[0129] parameter result Working Mode Bunching Resolution 0.3m Frame rate 10Hz Image size 1024×1024

[0130] Table 2

[0131] In one embodiment, if Figure 2 As shown, a system for rapid imaging of video synthetic aperture radar includes: a radar data reading module 1101, a sub-aperture blocking module 1102, an imaging module 1103 and a video stream generating module 1104;

[0132] The radar data reading module 1101 is used to read video SAR echo data and auxiliary data;

[0133] The sub-aperture blocking module 1102 is used to calculate the sub-aperture length according to the auxiliary data, and perform sub-aperture blocking on the video SAR echo data according to the sub-aperture length to obtain the blocked video SAR echo data;

[0134] The imaging module 1103 is used to perform sub-aperture imaging on the divided video SAR echo data to obtain a sub-aperture imaging result for each frame;

[0135] The video stream generation module 1104 is used to perform weighted superposition on each frame of sub-aperture imaging results according to the constructed multiple sub-aperture weighting coefficient factors to obtain multiple frames of images, and generate a radar image video stream according to the multiple frames of images.

[0136] The scheme is a video SAR fast imaging under high frame rate conditions. The video synthetic aperture radar fast imaging method provided by the present invention reads video SAR echo data and auxiliary data; constructs an imaging coordinate system according to an observation scene; performs sub-aperture blocking on the original echo data; performs sub-aperture imaging on the blocked data; constructs sub-aperture weighting coefficient factors; performs weighted superposition on the sub-aperture images for each frame; generates a radar image video stream, which can realize video synthetic aperture radar fast imaging and output a continuous video stream. The method has strong practicality and is applicable to various complex scenes. As a key step in video synthetic aperture radar imaging, the method is applicable to real-time processing board implementation.

[0137] Optionally, in any of the above embodiments, it further comprises: a weighting factor construction module, used to construct a weighted window function;

[0138] The weighted window function is divided into multiple segments, and a quadratic polynomial is fitted to each segment of the weighted window function data to obtain multiple sub-aperture weighting coefficient factors; wherein the multiple sub-aperture weighting coefficient factors include: a constant term parameter C(g), a linear term parameter L(g), and a quadratic term parameter Q(g).

[0139] Optionally, in any of the above embodiments, the video stream generation module 1104 is specifically configured to calculate multiple frames of images according to a first formula, wherein the first formula is:

[0140] I i =I c g+i-1 ·C(g)+I L g+i-1 ·L(g)+I Q g+i-1 Q(g),

[0141] Where i represents the serial number of the image frame, C(g) represents the constant term parameter, L(g) represents the linear term parameter, and Q(g) represents the quadratic term parameter. and It represents the three groups of imaging results of each sub-aperture, and the superscript g+i-1 represents the g+i-1th sub-aperture.

[0142] Optionally, in any of the above embodiments, the imaging module 1103 is specifically used to transform the latitude sequence, longitude sequence, and altitude sequence of the payload platform into an earth-centered earth-fixed coordinate system to obtain a first coordinate in the earth-centered earth-fixed coordinate system;

[0143] According to the first coordinate of the payload platform in the earth-centered earth-fixed coordinate system and the second coordinate of the imaging grid point in the earth-centered earth-fixed coordinate system, a slant distance between the first coordinate and the second coordinate at each pulse time is obtained;

[0144] According to the slant distance, a back-projection imaging algorithm is used to image each sub-aperture within an imaging grid to obtain sub-aperture imaging results for each frame.

[0145] Optionally, in any of the above embodiments, the auxiliary data includes: radar system parameters, payload platform motion parameters, imaging grid parameters and video frame frequency;

[0146] The sub-aperture blocking module 1102 is specifically configured to calculate the sub-aperture length according to the pulse repetition frequency in the auxiliary data and the frame frequency of the image of the video stream to be output.

[0147] It can be understood that in some embodiments, some or all of the optional implementation modes in the above embodiments may be included.

[0148] It should be noted that the above embodiments are product embodiments corresponding to the previous method embodiments. For the description of the optional implementation methods in the product embodiments, reference can be made to the corresponding description in the above method embodiments, which will not be repeated here.

[0149] The reader should understand that in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0150] 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 method embodiments described above are only illustrative, for example, the division of steps is only a logical function division, and there may be other division methods in actual implementation, such as multiple steps can be combined or integrated into another step, or some features can be ignored or not executed.

[0151] If the above method 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, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, server, or 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.

[0152] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for rapid imaging of video synthetic aperture radar, characterized in that: include: Read video SAR echo data and auxiliary data; Calculating a sub-aperture length according to the auxiliary data, performing sub-aperture block division on the video SAR echo data according to the sub-aperture length, and obtaining the divided video SAR echo data; Performing sub-aperture imaging on the divided video SAR echo data to obtain sub-aperture imaging results for each frame; According to the constructed multiple sub-aperture weighting coefficient factors, weighted superposition is performed on each frame of sub-aperture imaging results to obtain multiple frames of images, and a radar image video stream is generated according to the multiple frames of images; Constructing the plurality of sub-aperture weighting coefficient factors specifically includes: Construct a weighted window function; The weighted window function is divided into multiple segments, and a quadratic polynomial is fitted to each segment of the weighted window function data to obtain multiple sub-aperture weighted coefficient factors; wherein the multiple sub-aperture weighted coefficient factors include: a constant term parameter C(g), a linear term parameter L(g), and a quadratic term parameter Q(g); The step of performing weighted superposition on each frame of sub-aperture imaging results according to the constructed multiple sub-aperture weighting coefficient factors to obtain multiple frames of images specifically includes: The multiple frames of images are calculated according to the first formula, wherein the first formula is: I i =I c g+i-1 ·C(g)+I L g+i-1 ·L(g)+I Q g+i-1 ·Q(g), Where i represents the serial number of the image frame, C(g) represents the constant term parameter, L(g) represents the linear term parameter, and Q(g) represents the quadratic term parameter. and It represents the three groups of imaging results of each sub-aperture, and the superscript g+i-1 represents the g+i-1th sub-aperture.

2. The method for rapid video synthetic aperture radar imaging according to claim 1, characterized in that: The performing sub-aperture imaging on the divided video SAR echo data to obtain a sub-aperture imaging result for each frame specifically includes: The latitude sequence, longitude sequence and altitude sequence of the payload platform are transformed into the Earth-centered Earth-fixed coordinate system to obtain the first coordinate in the Earth-centered Earth-fixed coordinate system; According to the first coordinate of the payload platform in the earth-centered earth-fixed coordinate system and the second coordinate of the imaging grid point in the earth-centered earth-fixed coordinate system, a slant distance between the first coordinate and the second coordinate at each pulse time is obtained; According to the slant distance, a back-projection imaging algorithm is used to image each sub-aperture within an imaging grid to obtain sub-aperture imaging results for each frame.

3. The method for rapid video synthetic aperture radar imaging according to claim 1, characterized in that: The auxiliary data includes: radar system parameters, payload platform motion parameters, imaging grid parameters and video frame frequency; The calculating the sub-aperture length according to the auxiliary data specifically includes: The sub-aperture length is calculated according to the pulse repetition frequency in the auxiliary data and the frame frequency of the image of the video stream to be output.

4. A video synthetic aperture radar rapid imaging system, characterized in that: include: Radar data reading module, sub-aperture segmentation module, imaging module and video stream generation module; The radar data reading module is used to read video SAR echo data and auxiliary data; The sub-aperture blocking module is used to calculate the sub-aperture length according to the auxiliary data, and perform sub-aperture blocking on the video SAR echo data according to the sub-aperture length to obtain the blocked video SAR echo data; The imaging module is used to perform sub-aperture imaging on the divided video SAR echo data to obtain sub-aperture imaging results for each frame; The video stream generation module is used to perform weighted superposition on each frame of sub-aperture imaging results according to the constructed multiple sub-aperture weighting coefficient factors to obtain multiple frames of images, and generate a radar image video stream according to the multiple frames of images; Also included: a weighting factor building module for constructing a weighted window function; The weighted window function is divided into multiple segments, and a quadratic polynomial is fitted to each segment of the weighted window function data to obtain multiple sub-aperture weighted coefficient factors; wherein the multiple sub-aperture weighted coefficient factors include: a constant term parameter C(g), a linear term parameter L(g), and a quadratic term parameter Q(g); The video stream generation module is specifically used to calculate multiple frames of images according to a first formula, wherein the first formula is: I i =I c g+i-1 ·C(g)+I L g+i-1 ·L(g)+I Q g+i-1 ·Q(g), Where i represents the serial number of the image frame, C(g) represents the constant term parameter, L(g) represents the linear term parameter, and Q(g) represents the quadratic term parameter. and It represents the three groups of imaging results of each sub-aperture, and the superscript g+i-1 represents the g+i-1th sub-aperture.

5. The video synthetic aperture radar rapid imaging system according to claim 4, characterized in that: The imaging module is specifically used to transform the latitude sequence, longitude sequence and altitude sequence of the payload platform into an earth-centered earth-fixed coordinate system to obtain a first coordinate in the earth-centered earth-fixed coordinate system; According to the first coordinate of the payload platform in the earth-centered earth-fixed coordinate system and the second coordinate of the imaging grid point in the earth-centered earth-fixed coordinate system, a slant distance between the first coordinate and the second coordinate at each pulse time is obtained; According to the slant distance, a back-projection imaging algorithm is used to image each sub-aperture within an imaging grid to obtain sub-aperture imaging results for each frame.

6. The video synthetic aperture radar rapid imaging system according to claim 5, characterized in that: The auxiliary data includes: radar system parameters, payload platform motion parameters, imaging grid parameters and video frame frequency; The sub-aperture blocking module is specifically used to calculate the sub-aperture length according to the pulse repetition frequency in the auxiliary data and the frame frequency of the image of the video stream to be output.

Images