Synthetic aperture radar large squint imaging motion compensation method

Abstract

The invention relates to the technical field of synthetic aperture radars, and discloses a synthetic aperture radar large squint imaging motion compensation method comprising the following steps: collecting echo data of a synthetic aperture radar and attitude information and motion data of a synthetic aperture radar installation platform in real time, the attitude information comprising position data and attitude data of the installation platform; the motion data comprises speed and acceleration; determining a radar beam direction vector according to the attitude data, determining a line-of-sight direction vector according to the position data, and determining a squint angle based on the radar beam direction vector and the line-of-sight direction vector; determining a phase compensation value of the echo data based on the squint angle and the motion data; and compensating the echo data, and performing image reconstruction on the compensated echo data by adopting an image algorithm. According to the invention, phase compensation is carried out on the echo data, and image blurring and distortion caused by platform motion can be reduced, so that the definition and the accuracy of a final image are improved, and the dynamic performance and the stability of the whole system are improved.

Description

Technical Field

[0001] The invention relates to the technical field of synthetic aperture radar, in particular to a synthetic aperture radar high squint imaging motion compensation method. Background Art

[0002] Synthetic Aperture Radar (SAR) is a high-resolution imaging radar system that can accurately image the ground in all weather and lighting conditions.

[0003] The working principle of synthetic aperture radar (SAR) is based on synthetic aperture technology, which simulates a huge antenna aperture through the movement of the antenna on a mobile platform (such as a satellite or an aircraft) to achieve high-resolution imaging. Unlike traditional real aperture radar, SAR transmits a series of pulse signals and receives the reflected signals, and uses the phase difference of these signals to synthesize a larger virtual aperture, thereby significantly improving the resolution. SAR systems can work in any weather conditions, including harsh environments such as clouds, rain, snow, fog and haze, which is a major advantage over optical imaging technology. This capability makes SAR have broad application prospects in military reconnaissance, disaster monitoring, resource exploration and other fields. The resolution of SAR images is very high and can distinguish small features on the surface, such as buildings, trees, rivers, etc. This high-resolution imaging capability is crucial for geological exploration, environmental monitoring and other fields.

[0004] In practical applications, factors such as flight path changes and terrain undulations will cause the relative angle between the radar beam and the target area to change, which is called the "squint" phenomenon. This squint effect will seriously affect the quality of SAR images, causing image blur and distortion. Therefore, a synthetic aperture radar high squint imaging motion compensation method is urgently needed to achieve effective motion compensation under high squint conditions. Summary of the invention

[0005] The purpose of the present invention is to provide a synthetic aperture radar high squint imaging motion compensation method to solve the problem that in practical applications, due to factors such as flight path changes and terrain undulations, the relative angle between the radar beam and the target area changes, resulting in a "squint" phenomenon. This squint effect will seriously affect the quality of SAR images, resulting in image blur and distortion.

[0006] The present invention provides a synthetic aperture radar high squint imaging motion compensation method, comprising: Collecting in real time the echo data of the synthetic aperture radar, as well as the attitude information and motion data of the synthetic aperture radar installation platform, wherein the attitude information includes the position data and attitude data of the installation platform, and the motion data includes the speed and acceleration; Determine a radar beam direction vector according to the attitude data, determine a sight line direction vector of the installation platform according to the position data, and determine a squint angle between the synthetic aperture radar and the target area based on the radar beam direction vector and the sight line direction vector; Determining a phase compensation value of the echo data based on the squint angle and the motion data; The echo data is compensated based on the phase compensation value, and an image algorithm is used to reconstruct an image of the compensated echo data.

[0007] Preferably, determining the radar beam direction vector according to the attitude data includes: The attitude data includes azimuth and pitch angle; The radar beam direction is converted into a vector in a Cartesian coordinate system according to the azimuth angle and the elevation angle to obtain a radar beam direction vector.

[0008] Preferably, the conversion formula for converting the radar beam direction into a vector in a Cartesian coordinate system according to the azimuth angle and the elevation angle is:

[0009] in, represents the azimuth, represents the pitch angle, x, y, z represent the components of the vector in the Cartesian coordinate system; The radar beam direction vector is expressed as:

[0010] in, Represents the radar beam direction vector.

[0011] Preferably, determining the sight direction vector of the installation platform according to the position data includes: The location data includes the longitude, latitude and altitude of the installation platform; Determining target location data of the target area, wherein the target location data includes longitude, latitude and altitude of the target area; The sight direction vector of the installation platform is determined according to the position data and the target position data.

[0012] Preferably, when determining the sight line direction vector of the installation platform according to the position data and the target position data, the sight line direction vector of the installation platform is determined by the following formula:

[0013] in, represents the sight direction vector, a, b, c represent the components of the sight direction vector, lo1 represents the longitude of the installation platform, la1 represents the latitude of the installation platform, h1 represents the height of the installation platform, lo2 represents the longitude of the target area, la2 represents the latitude of the target area, h2 represents the height of the target area, d1 represents the unit length of the current longitude, and d2 represents the unit length of the current latitude.

[0014] Preferably, determining the squint angle between the synthetic aperture radar and the target area based on the radar beam direction vector and the line of sight direction vector includes: Determining a cosine value of an angle between the radar beam direction vector and the sight direction vector; Determine the squint angle between the synthetic aperture radar and the target area according to the cosine value of the angle; The cosine value of the angle is determined according to the following formula:

[0015] The squint angle is determined according to the following formula:

[0016] in, It represents the squint angle between the synthetic aperture radar and the target area.

[0017] Preferably, determining the phase compensation value of the echo data based on the squint angle and the motion data comprises: determining a motion model of the installation platform according to the motion data; Determine the distance between the installation platform and the target area according to the squint angle and the motion model; Determining a propagation delay of a synthetic aperture radar based on the distance ; Determine the wavelength of the synthetic aperture radar, and determine the Doppler shift of the synthetic aperture radar based on the wavelength and the motion data ; determining the phase of the echo data according to the propagation delay and the Doppler shift; A phase compensation value of the echo data is determined according to the motion model and the phase of the echo data.

[0018] Preferably, the motion model is expressed as:

[0019] Wherein, P(t) represents the position after movement, P0 represents the initial position of the mounting platform, V represents the velocity of the mounting platform, A represents the acceleration of the mounting platform, and t represents the echo data acquisition time.

[0020] Preferably, the propagation delay of the synthetic aperture radar Determined according to the following formula:

[0021] Doppler shift of synthetic aperture radar Determined according to the following formula:

[0022] The phase of the echo data is determined according to the following formula:

[0023] The phase compensation value of the echo data is determined according to the following formula:

[0024] Where D is the distance between the installation platform and the target area, c is the speed of light, and V is the speed of the installation platform. represents the wavelength of synthetic aperture radar, represents the phase of the echo data, f0 represents the center frequency of the synthetic aperture radar, Indicates the phase compensation value of the echo data, Indicates the reference phase.

[0025] Preferably, when the echo data is compensated based on the phase compensation value, compensation is performed according to the following formula:

[0026] in, Represents the echo data after compensation, Indicates echo data.

[0027] Compared with the prior art, the beneficial effect of the present invention is that the present invention can reduce image blur and distortion caused by platform motion by performing phase compensation on echo data, thereby improving the clarity and accuracy of the final image. Real-time acquisition and utilization of attitude information and motion data helps to more accurately track and predict the motion state of the platform, thereby improving the dynamic performance and stability of the entire system. The use of efficient image algorithms to process compensated echo data can speed up image reconstruction and shorten the time period from data acquisition to image generation. The large squint imaging mode allows the SAR system to operate at a wider viewing angle, which is particularly important for monitoring tasks in complex terrain or specific directions. Through effective motion compensation methods, high-quality images can be obtained in more cases. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0029] Figure 1 The present invention is a flowchart of a method for motion compensation of synthetic aperture radar high squint imaging. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] like Figure 1 As shown, the present invention provides a synthetic aperture radar high squint imaging motion compensation method, comprising: The echo data of the synthetic aperture radar, as well as the attitude information and motion data of the synthetic aperture radar installation platform are collected in real time, wherein the attitude information includes the position data and attitude data of the installation platform, and the motion data includes speed and acceleration.

[0032] A radar beam direction vector is determined according to the posture data, a sight line direction vector of the installation platform is determined according to the position data, and a squint angle between the synthetic aperture radar and the target area is determined based on the radar beam direction vector and the sight line direction vector.

[0033] A phase compensation value for the echo data is determined based on the squint angle and motion data.

[0034] The echo data is compensated based on the phase compensation value, and an image algorithm is used to reconstruct an image of the compensated echo data.

[0035] The present invention relates to a synthetic aperture radar (SAR) high squint imaging motion compensation method, which can effectively improve the image quality acquired at a high squint angle, and is particularly suitable for a SAR system carried by an aircraft. The specific steps are as follows: Real-time acquisition: First, the echo data of the synthetic aperture radar is collected in real time. These data are the signals returned after the radar beam interacts with the ground target, and contain detailed information about the target area. At the same time, the attitude information and motion data of the synthetic aperture radar installation platform are collected. The attitude information includes the location data (such as longitude, latitude, and altitude) and attitude data (such as azimuth and pitch angle) of the installation platform. The motion data includes speed and acceleration, which reflect the motion state of the installation platform in space.

[0036] Determine the beam direction and line of sight direction: Determine the radar beam direction vector based on the collected attitude data. The beam direction vector reflects the spatial direction of the radar beam. At the same time, determine the line of sight direction vector of the mounting platform based on the position data. The line of sight direction vector represents the straight line direction from the mounting platform to the target area. By comparing the radar beam direction vector and the line of sight direction vector, the squint angle between the synthetic aperture radar and the target area can be accurately calculated.

[0037] Determine the phase compensation value: The squint angle and motion data together determine the phase error of the echo data. Based on the squint angle and motion data, the phase compensation value of the echo data can be calculated. This compensation value is used to correct the phase distortion caused by the angle change between the radar beam and the target area and the platform movement.

[0038] Echo data compensation and image reconstruction: The calculated phase compensation value is used to compensate the echo data to eliminate or reduce the phase error caused by motion. The compensated echo data more accurately reflects the actual situation of the target area. Finally, the image algorithm is used to reconstruct the compensated echo data to generate high-quality SAR images. The image algorithm can be a traditional imaging algorithm, such as the range-Doppler algorithm (RD algorithm), Chirp Scaling algorithm, etc., or a more advanced algorithm, such as an imaging algorithm based on compressed sensing.

[0039] Through the above steps, the method provided by the present invention can effectively perform motion compensation on SAR images at large squint angles, thereby improving image quality and ensuring that clear and accurate ground imaging results can be obtained under various flight conditions.

[0040] In some embodiments of the present application, determining a radar beam direction vector according to the attitude data includes: the attitude data includes an azimuth and an elevation angle; converting the radar beam direction into a vector in a Cartesian coordinate system according to the azimuth and the elevation angle to obtain the radar beam direction vector.

[0041] In some embodiments of the present application, the conversion formula for converting the radar beam direction into a vector in a Cartesian coordinate system according to the azimuth angle and the elevation angle is:

[0042] in, represents the azimuth, represents the pitch angle, x, y, z represent the components of the vector in the Cartesian coordinate system; The radar beam direction vector is expressed as:

[0043] in, Represents the radar beam direction vector.

[0044] In this embodiment, the steps of determining the radar beam direction vector are as follows: Get attitude data: First, you need to get the attitude data of the current device, which usually includes azimuth and elevation.

[0045] Definition of azimuth and elevation: Azimuth: The angle measured clockwise from the north to the target direction, usually ranging from 0 degrees to 360 degrees. Elevation: The angle measured upward or downward from the horizontal plane to the target direction, usually ranging from -90 degrees to +90 degrees.

[0046] Convert to Cartesian coordinates: Assume that the radar is located at the origin, with an azimuth angle of θ and an elevation angle of φ. In the Cartesian coordinate system, the position of a point can be represented by three coordinate values ​​(x, y, z). Based on the azimuth and elevation angles, the radar beam direction can be converted into a vector (x, y, z) in the Cartesian coordinate system.

[0047] Compute vector components: x = cos(φ) * cos(θ) y = cos(φ) * sin(θ) z = sin(φ) Get the radar beam direction vector: Combine the calculated x, y, and z values ​​into a vector, which is the radar beam direction vector.

[0048] For example, if the azimuth angle is 45 degrees (θ = 45°) and the elevation angle is 30 degrees (φ = 30°), the radar beam direction vector in Cartesian coordinates is: x = cos(30°) * cos(45°) y = cos(30°) * sin(45°) z = sin(30°) After calculation, the radar beam direction vector is: x ≈ 0.866 * 0.707 ≈ 0.612 y ≈ 0.866 * 0.707 ≈ 0.612 z ≈ 0.5 Therefore, the radar beam direction vector is approximately (0.612, 0.612, 0.5).

[0049] In some embodiments of the present application, the line of sight direction vector of the installation platform is determined based on the position data, including: the position data includes the longitude, latitude and altitude of the installation platform; target position data of the target area is determined, and the target position data includes the longitude, latitude and altitude of the target area; and the line of sight direction vector of the installation platform is determined based on the position data and the target position data.

[0050] In some embodiments of the present application, when determining the sight line direction vector of the installation platform according to the position data and the target position data, the sight line direction vector of the installation platform is determined by the following formula:

[0051] in, represents the sight direction vector, a, b, c represent the components of the sight direction vector, lo1 represents the longitude of the installation platform, la1 represents the latitude of the installation platform, h1 represents the height of the installation platform, lo2 represents the longitude of the target area, la2 represents the latitude of the target area, h2 represents the height of the target area, d1 represents the unit length of the current longitude, and d2 represents the unit length of the current latitude.

[0052] In this embodiment, in order to determine the sight direction vector of the mounting platform, it is first necessary to obtain the precise location data of the mounting platform, which includes its geographic coordinates (longitude and latitude) and its height relative to the earth's surface. These data can be provided by a global positioning system (GPS) or other geographic positioning technologies.

[0053] Collect location data for the installation platform: Longitude: The east / west coordinate of the location where the installation platform is located.

[0054] Latitude: The North / South coordinate of the location where the mounting platform is located.

[0055] Height: The height of the mounting platform relative to mean sea level.

[0056] Determine the target location data for the target area: Longitude of target area: The east / west coordinate of the target area.

[0057] Latitude of target area: The north / south coordinate of the target area.

[0058] Height of target area: The height of the target area relative to mean sea level.

[0059] Calculate the view direction vector: Using the location data of the mounting platform and the location data of the target area, the sight direction vector can be calculated by vector analysis. First, the vector from the mounting platform to the target area is calculated, that is, the three-dimensional coordinates of the target area minus the three-dimensional coordinates of the mounting platform. Then, the longitude and latitude in the obtained three-dimensional coordinates are distance-normalized to obtain the sight direction vector.

[0060] By following the above steps, the sight direction vector from the mounting platform to the target area can be accurately determined, which is critical for installing directional equipment, conducting remote communications, navigation, or other applications that require precise direction.

[0061] Understandably, different latitudes and longitudes have different lengths. The Earth is a nearly spherical ellipsoid with a larger equatorial radius than a polar radius. This shape means that the length of the lines of latitude (circles parallel to the equator) varies with latitude, while the length of the lines of longitude (large circles connecting the North and South Poles) converges to zero at the poles. The lines of latitude are parallel to each other, and each circle of latitude is the same size only as the corresponding circle in the other hemisphere. At the equator, the circles of latitude are the largest, so the distance represented by one degree of latitude is also the longest, about 111 kilometers. As latitude increases, the circles of latitude gradually decrease, so the distance represented by one degree of latitude varies slightly in mid-latitudes. At the poles, the length of the lines of latitude is zero. All the meridians converge at points at the poles, so all the meridian circles are the same size. However, because meridians are abstract concepts and not physical lines, the length of meridians decreases as latitude increases from the equator to the poles on the Earth. Near the equator, the length of longitude is about 111 kilometers, while at the poles, the meridians converge and the length is 0. Therefore, in this embodiment, the lengths represented by d1 and d2 are determined according to the longitude and latitude.

[0062] In some embodiments of the present application, determining the squint angle between the synthetic aperture radar and the target area based on the radar beam direction vector and the sight line direction vector includes: determining a cosine value of an angle between the radar beam direction vector and the sight line direction vector; determining the squint angle between the synthetic aperture radar and the target area according to the cosine value of the angle; The cosine value of the angle is determined according to the following formula:

[0063] The squint angle is determined according to the following formula:

[0064] in, It represents the squint angle between the synthetic aperture radar and the target area.

[0065] In this embodiment, determining the squint angle between the synthetic aperture radar and the target area based on the radar beam direction vector and the line of sight direction vector includes the following steps: Determine the cosine of the angle between the radar beam direction vector and the line of sight direction vector. This can be done by calculating the dot product of the two vectors and their respective magnitudes. Specifically, if the radar beam direction vector is represented by , and the sight direction vector is expressed as , then the cosine of the angle can be calculated using the dot product formula.

[0066] The squint angle between the synthetic aperture radar and the target area is determined according to the cosine value of the included angle. The squint angle can be calculated by the arccosine function (arccos).

[0067] Through the above steps, the squint angle between the synthetic aperture radar and the target area can be determined, which is the angle between the synthetic aperture radar beam direction and the line of sight direction.

[0068] In some embodiments of the present application, determining the phase compensation value of the echo data based on the squint angle and the motion data includes: determining a motion model of the installation platform according to the motion data; determining a distance between the installation platform and the target area according to the squint angle and the motion model; determining a propagation delay of a synthetic aperture radar based on the distance. ; Determine the wavelength of the synthetic aperture radar, and determine the Doppler shift of the synthetic aperture radar based on the wavelength and motion data ; determining the phase of the echo data according to the propagation delay and the Doppler frequency shift; determining the phase compensation value of the echo data according to the motion model and the phase of the echo data.

[0069] In order to accurately process the echo data obtained by the synthetic aperture radar (SAR) system, it is necessary to perform phase compensation on these data to correct the phase error caused by platform motion and squint angle. The following are the detailed steps: Determine the motion model of the mounting platform based on the motion data: First, analyze the motion data of the platform, which may include information such as position, velocity, and acceleration. Using this data, a mathematical model describing the motion of the platform can be established, such as a linear motion model, a polynomial motion model, or other more complex dynamic models.

[0070] Determine the distance between the installation platform and the target area based on the squint angle and the motion model: Combined with the motion model, the distance between the platform and the target area at different time points can be calculated.

[0071] Determine the propagation delay ∆t of synthetic aperture radar based on distance: Propagation delay is the time it takes for a radar signal to be transmitted and received. The propagation delay ∆t can be determined by calculating the total distance the signal has traveled to and from the target area.

[0072] Determine the wavelength of the synthetic aperture radar: Wavelength is an inherent property of the radar signal and is usually determined by the operating frequency of the radar system. Wavelength is a key parameter in calculating the Doppler shift. Determine the Doppler shift ∆f of the synthetic aperture radar based on wavelength and motion data: The Doppler shift is the change in frequency caused by the motion of the platform and the relative motion of the target. Using the wavelength and the platform's motion data, the Doppler shift ∆f can be calculated.

[0073] Determine the phase of the echo data based on the propagation delay and Doppler shift: The phase of the echo signal is affected by the propagation delay and Doppler shift. By calculating the contribution of these two factors to the phase, the total phase of the echo data can be obtained.

[0074] Determine the phase compensation value of the echo data based on the motion model and the phase of the echo data: Finally, using the motion model and the calculated phase of the echo data, the phase compensation value that needs to be applied to the echo data can be determined. This compensation value will be used to correct the phase error caused by platform motion and squint angle, thereby improving the quality and accuracy of the SAR image.

[0075] In some embodiments of the present application, the motion model is expressed as:

[0076] Wherein, P(t) represents the position after movement, P0 represents the initial position of the mounting platform, V represents the velocity of the mounting platform, A represents the acceleration of the mounting platform, and t represents the echo data acquisition time.

[0077] In some embodiments of the present application, the propagation delay of the synthetic aperture radar Determined according to the following formula:

[0078] Doppler shift of synthetic aperture radar Determined according to the following formula:

[0079] The phase of the echo data is determined according to the following formula:

[0080] The phase compensation value of the echo data is determined according to the following formula:

[0081] Where D is the distance between the installation platform and the target area, c is the speed of light, and V is the speed of the installation platform. represents the wavelength of synthetic aperture radar, represents the phase of the echo data, f0 represents the center frequency of the synthetic aperture radar, Indicates the phase compensation value of the echo data, Indicates the reference phase.

[0082] It can be understood that determining the distance between the installation platform and the target area based on the squint angle and the motion model includes: determining the initial position and the position after movement of the installation platform based on the motion model, and determining that the angle corresponding to the side between the initial position and the position after movement in the triangle formed by the initial position, the position after movement and the target area is the squint angle, and the distance between the installation platform after movement and the target area can be determined based on the squint angle and the initial position and the position after movement of the installation platform through trigonometric functions.

[0083] In some embodiments of the present application, when the echo data is compensated based on the phase compensation value, compensation is performed according to the following formula:

[0084] in, Represents the echo data after compensation, represents echo data, and j represents an imaginary unit.

[0085] In this embodiment, after the compensated echo data is obtained, an image algorithm is used to reconstruct the compensated echo data. The image reconstruction techniques that can be used include: using a range Doppler (RD) algorithm, a compressed sensing (CS) algorithm, or a range-angle-based motion compensation algorithm (RMA), etc. These algorithms can effectively process non-uniform motion targets and can obtain higher imaging resolution. And select a suitable algorithm according to specific application scenarios and requirements. For example, the RD algorithm is suitable for targets with uniform linear motion, the CS algorithm is suitable for low sampling rate imaging of sparse targets, and the RMA algorithm is suitable for imaging targets with non-uniform motion.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

[0087] The system provided in the above embodiment is only illustrated by the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the modules or steps in the embodiments of the present invention can be decomposed or combined. For example, the modules in the above embodiment can be combined into one module, or further divided into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present invention are only for distinguishing the modules or steps, and are not regarded as improper limitations of the present invention.

[0088] Those skilled in the art should be able to appreciate that the modules and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, computer software or a combination of the two, and the programs corresponding to the software modules and method steps can be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs or any other form of storage medium known in the technical field. In order to clearly illustrate the interchangeability of electronic hardware and software, the composition and steps of each example have been generally described in the above description according to the function. Whether these functions are performed in electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

Claims

1. A method for motion compensation of synthetic aperture radar high squint imaging, characterized in that: include: Collecting in real time the echo data of the synthetic aperture radar, as well as the attitude information and motion data of the synthetic aperture radar installation platform, wherein the attitude information includes the position data and attitude data of the installation platform, and the motion data includes the speed and acceleration; Determine a radar beam direction vector according to the attitude data, determine a sight line direction vector of the installation platform according to the position data, and determine a squint angle between the synthetic aperture radar and the target area based on the radar beam direction vector and the sight line direction vector; Determining a phase compensation value of the echo data based on the squint angle and the motion data; The echo data is compensated based on the phase compensation value, and an image algorithm is used to reconstruct an image of the compensated echo data.

2. The method for motion compensation of synthetic aperture radar high squint imaging according to claim 1, characterized in that: Determining a radar beam direction vector according to the attitude data includes: The attitude data includes azimuth and pitch angle; The radar beam direction is converted into a vector in a Cartesian coordinate system according to the azimuth angle and the elevation angle to obtain a radar beam direction vector.

3. The method for motion compensation of synthetic aperture radar high squint imaging according to claim 2, characterized in that: The conversion formula for converting the radar beam direction into a vector in a Cartesian coordinate system according to the azimuth and elevation angles is: in, represents the azimuth, represents the pitch angle, x, y, z represent the components of the vector in the Cartesian coordinate system; The radar beam direction vector is expressed as: in, Represents the radar beam direction vector.

4. The method for motion compensation of synthetic aperture radar high squint imaging according to claim 3, characterized in that: Determining the sight direction vector of the installation platform according to the position data includes: The location data includes the longitude, latitude and altitude of the installation platform; Determining target location data of the target area, wherein the target location data includes longitude, latitude and altitude of the target area; The sight direction vector of the installation platform is determined according to the position data and the target position data.

5. The method for motion compensation of synthetic aperture radar high squint imaging according to claim 4, characterized in that: When determining the sight line direction vector of the installation platform according to the position data and the target position data, the sight line direction vector of the installation platform is determined by the following formula: in, represents the sight direction vector, a, b, c represent the components of the sight direction vector, lo1 represents the longitude of the installation platform, la1 represents the latitude of the installation platform, h1 represents the height of the installation platform, lo2 represents the longitude of the target area, la2 represents the latitude of the target area, h2 represents the height of the target area, d1 represents the unit length of the current longitude, and d2 represents the unit length of the current latitude.

6. The method for motion compensation of synthetic aperture radar high squint imaging according to claim 5, characterized in that: Determining the squint angle between the synthetic aperture radar and the target area based on the radar beam direction vector and the line of sight direction vector includes: Determining a cosine value of an angle between the radar beam direction vector and the sight direction vector; Determine the squint angle between the synthetic aperture radar and the target area according to the cosine value of the angle; The cosine value of the angle is determined according to the following formula: The squint angle is determined according to the following formula: in, It represents the squint angle between the synthetic aperture radar and the target area.

7. The method for motion compensation of synthetic aperture radar high squint imaging according to claim 6, characterized in that: Determining a phase compensation value of the echo data based on the squint angle and the motion data includes: determining a motion model of the installation platform according to the motion data; Determine the distance between the installation platform and the target area according to the squint angle and the motion model; Determining a propagation delay of a synthetic aperture radar based on the distance ; Determine the wavelength of the synthetic aperture radar, and determine the Doppler shift of the synthetic aperture radar based on the wavelength and the motion data ; determining the phase of the echo data according to the propagation delay and the Doppler shift; A phase compensation value of the echo data is determined according to the motion model and the phase of the echo data.

8. The method for motion compensation of synthetic aperture radar high squint imaging according to claim 7, characterized in that: The motion model is expressed as: Wherein, P(t) represents the position after movement, P0 represents the initial position of the mounting platform, V represents the velocity of the mounting platform, A represents the acceleration of the mounting platform, and t represents the echo data acquisition time.

9. The method for motion compensation of synthetic aperture radar high squint imaging according to claim 8, characterized in that: Propagation Delay of Synthetic Aperture Radar Determined according to the following formula: Doppler shift of synthetic aperture radar Determined according to the following formula: The phase of the echo data is determined according to the following formula: The phase compensation value of the echo data is determined according to the following formula: Where D is the distance between the installation platform and the target area, c is the speed of light, and V is the speed of the installation platform. represents the wavelength of synthetic aperture radar, represents the phase of the echo data, f0 represents the center frequency of the synthetic aperture radar, Indicates the phase compensation value of the echo data, Indicates the reference phase.

10. The method for motion compensation of synthetic aperture radar high squint imaging according to claim 9, characterized in that: When the echo data is compensated based on the phase compensation value, compensation is performed according to the following formula; in, Represents the echo data after compensation, Indicates echo data.

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