Helical trajectory flying vehicle synthetic aperture radar imaging method and device

Abstract

The application discloses a spiral trajectory glider synthetic aperture radar imaging method and device, and the method comprises the following steps: sequentially performing time domain and frequency domain compensation processing on echo signals through a time domain compensation function and a frequency domain compensation function to obtain two-dimensional frequency domain signals; wherein the time domain compensation function and the frequency domain compensation function are constructed according to the relationship between high-precision instantaneous slant range of any point in an imaging scene and instantaneous slant range of a reference point, and the instantaneous slant range is determined based on a spiral trajectory geometric model with rapid acceleration and speed change; and performing non-uniform fast Fourier transform on the two-dimensional frequency domain signals to obtain transformed two-dimensional frequency domain signals. The application can improve imaging precision.

Description

Technical Field

[0001] This invention belongs to the field of signal processing technology, specifically relating to a synthetic aperture radar imaging method and apparatus for a spiral trajectory gliding aircraft. Background Technology

[0002] Synthetic Aperture Radar (SAR) imaging technology can achieve air-to-ground imaging of objects, terrain, and oceans without being constrained by time, weather conditions, or distance. Over the past few decades, extensive research has been conducted on conventional SAR mounted on airborne or satellite platforms at certain altitudes, finding it highly effective in adverse weather or lighting conditions. Advanced SAR imaging technology is rapidly evolving. Unlike traditional SAR, glide vehicle curvilinear SAR operates at altitudes of 20 to 100 kilometers and speeds exceeding Mach 5, bridging the gap between airborne and satellite SAR. Glide vehicle curvilinear SAR can provide a larger weather observation area than aircraft and greater flexibility than satellites. Compared to traditional SAR, it features high survivability, fast response time, and wide detection range, enabling in-depth detection of sensitive areas, all-weather environmental monitoring, and the location of important targets, playing a crucial role in disaster monitoring and assessment. Glide vehicle helical trajectory SAR is a special type of curvilinear trajectory SAR imaging, possessing even stronger survivability and reconnaissance capabilities, demonstrating enormous potential for future development and application.

[0003] Current slant-range model-based curved trajectory SAR slant-view imaging methods derive analytical solutions for the two-dimensional spectrum by starting with the motion characteristics of a curved trajectory platform and performing high-order approximations on its motion equations. This method ensures the simplicity of the spectrum and has high accuracy, enabling full-aperture high-resolution imaging.

[0004] However, this method still has shortcomings. In SAR imaging of gliders with spiral trajectories, because the velocity and acceleration of the glider are not constant in various directions, the current slant range model does not accurately express the slant range under its spiral trajectory. Therefore, the compensation function constructed using the current slant range model has a poor compensation effect when used for SAR imaging of gliders with spiral trajectories, resulting in poor SAR imaging quality. At the same time, the large velocity and variable acceleration of the glider's spiral trajectory cause severe phase coupling and large spatial variation errors in the echo signal.

[0005] Therefore, the slant range model in the current SAR slant imaging method still does not have enough accuracy in describing the spiral trajectory, and cannot accurately compensate for the coupling spatial variation error caused by the spiral trajectory motion, resulting in poor imaging effect. Summary of the Invention

[0006] This invention provides a synthetic aperture radar imaging method and apparatus for a helical trajectory glider, which can solve the problems that the slant range model in the current SAR slant-view imaging method still does not have enough accuracy in describing the helical trajectory, and cannot accurately compensate for the coupling spatial variation error caused by the helical trajectory motion, resulting in poor imaging effect.

[0007] In a first aspect, embodiments of the present invention provide a synthetic aperture radar imaging method for a helical trajectory glider, the method comprising:

[0008] The echo signal is processed sequentially in the time domain and frequency domain by time domain compensation function and frequency domain compensation function to obtain a two-dimensional frequency domain signal;

[0009] The time-domain compensation function and the frequency-domain compensation function are constructed based on the relationship between the high-precision instantaneous slant range of any point in the imaging scene and the instantaneous slant range of the reference point. The instantaneous slant range is determined based on the geometric model of a spiral trajectory with rapid acceleration and velocity changes.

[0010] A non-uniform fast Fourier transform is performed on the two-dimensional frequency domain signal to obtain the transformed two-dimensional frequency domain signal;

[0011] The focused image is obtained by performing an inverse Fourier transform on the transformed two-dimensional frequency domain signal.

[0012] Secondly, embodiments of the present invention provide a synthetic aperture radar imaging device for a helical trajectory glider, comprising:

[0013] The compensation module is used to perform time-domain and frequency-domain compensation processing on the echo signal sequentially using time-domain compensation functions and frequency-domain compensation functions to obtain a two-dimensional frequency-domain signal.

[0014] The time-domain compensation function and the frequency-domain compensation function are constructed based on the relationship between the high-precision instantaneous slant range of any point in the imaging scene and the instantaneous slant range of the reference point. The instantaneous slant range is determined based on the geometric model of a spiral trajectory with rapid acceleration and velocity changes.

[0015] The Fourier transform module performs a non-uniform fast Fourier transform on a two-dimensional frequency domain signal to obtain a transformed two-dimensional frequency domain signal; and performs an inverse Fourier transform on the transformed two-dimensional frequency domain signal to obtain a focused image of the aircraft.

[0016] Thirdly, embodiments of the present invention provide an electronic device, including a processor and a memory, wherein the memory is used to store a computer program; the processor can be used to execute a calculator program (instructions) stored in the memory to implement the method of the first aspect described above.

[0017] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows: Since the high-precision instantaneous slant range and instantaneous slant range used in the present invention are constructed based on the geometric model of the spiral trajectory, the speed and acceleration changes of the aircraft moving in the spiral trajectory are fully considered; therefore, by constructing a compensation function through high-precision instantaneous slant range and instantaneous slant range, and by compensating the echo signal through this compensation function, the compensation effect of the compensation function can be improved, thereby improving the imaging quality of the spiral trajectory; removing the coupling spatial variation error in the phase through non-uniform fast Fourier transform can also improve the imaging quality and accuracy. Attached Figure Description

[0018] Figure 1 A flowchart illustrating the implementation of a method for constructing a high-precision instantaneous slant range model provided in this embodiment of the invention;

[0019] Figure 2 A top view of a spiral trajectory motion provided in an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of a spiral trajectory motion provided in an embodiment of the present invention;

[0021] Figure 4 A schematic diagram illustrating the implementation process of a synthetic aperture radar imaging method for a helical trajectory glider provided in an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of a synthetic aperture radar imaging device for a spiral trajectory glider provided in an embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of the SAR imaging effect of a spiral trajectory glider provided in an embodiment of the present invention;

[0024] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0026] Example 1

[0027] Figure 1 The diagram illustrates a flowchart of a method for constructing a high-precision instantaneous slant range model according to an embodiment of the present invention. As an example and not a limitation, the slant range model construction method may include steps S101-S102, which are described below.

[0028] S101, Construct a geometric model of the spiral trajectory.

[0029] In one example, a geometric model of the spiral trajectory can be constructed using the acceleration, velocity, and position model of the aircraft during its spiral trajectory motion, thereby obtaining the coordinates of the aircraft in a three-dimensional coordinate system.

[0030] For example, the position model of an aircraft can be represented as:

[0031]

[0032]

[0033] in, Polar radius, For the polar angle of response, Angular velocity of rotation For location, slow time, The integral constant The angle between the component of the velocity vector in the yaw plane and the polar radius.

[0034] For example, see Figure 2 The platform radar mounted on the aircraft will rotate counterclockwise around the rotation axis when the aircraft is in a spiral motion.

[0035] For example, the acceleration and velocity of an aircraft can be expressed as:

[0036]

[0037]

[0038]

[0039] in, For acceleration, As resistance, m For quality, Gravitational acceleration, For the track angle, Instantaneous velocity The initial velocity is... Vertical velocity, For the track deflection angle, Vertical initial velocity, This is the vertical acceleration.

[0040] For example, the geometric model of the spiral trajectory obtained through geometric relationships (i.e., the coordinates of the aircraft in a three-dimensional coordinate system) can be represented as:

[0041]

[0042] in, , , These are the three-dimensional coordinates of the aircraft. This is the initial platform height.

[0043] S102, a high-precision instantaneous slant distance model is constructed based on the geometric model of the spiral trajectory.

[0044] In one possible implementation, the instantaneous slant range of a reference point within the radar imaging scene can be Taylor-expanded based on a helical trajectory geometric model to obtain the Taylor expansion coefficients of the instantaneous slant range of the reference point; the instantaneous slant range of any point A of the aircraft within the imaging scene can be Taylor-expanded using the reference point as a reference, and then multiple fittings can be performed to simplify the multidimensional Taylor coefficients of point A; the simplified instantaneous slant range of point A can be reconstructed to obtain a high-precision instantaneous slant range model.

[0045] In one example, see Figure 3 The instantaneous slant range expression of the reference point C can be obtained from the imaging geometry model, and then the absolute value can be taken to obtain the instantaneous slant range of the reference point.

[0046] For example, the instantaneous slope distance of reference point C The following formula can be satisfied:

[0047] ;

[0048] For example, the instantaneous slope distance of reference point C can be expressed as:

[0049]

[0050] in, The instantaneous vector of the platform radar reaching the reference point. , , These are the coordinates of reference point C. , , These are the coordinates of the platform's radar.

[0051] In one example, the higher-order Taylor expansion of the instantaneous slant distance of reference point C can be expressed as:

[0052]

[0053] in, Let be the Taylor expansion coefficient of the instantaneous slant distance at reference point C.

[0054] Each coefficient satisfies:

[0055]

[0056]

[0057]

[0058]

[0059]

[0060] in, ω is the rotational angular velocity.

[0061] In one example, see Figure 3 Based on the geometric relationship between point A and reference point C, the instantaneous slant range of any point A within the radar imaging scene can be obtained. Expanding the instantaneous slant range of point A yields its Taylor expansion and each Taylor expansion coefficient. Performing a Taylor expansion using the reference point as a reference yields the multidimensional Taylor expansion coefficients of the instantaneous slant range of point A. Fitting each of these multidimensional Taylor expansion coefficients yields simplified expressions. Reconstructing the instantaneous slant range of point A using these simplified expressions results in a high-precision instantaneous slant range model.

[0062] For example, the Taylor expansion of the instantaneous slope distance of point A can be expressed as:

[0063]

[0064] in, Let A be the instantaneous slope distance. Let A be the polar radius. Let be the Taylor expansion coefficient of the instantaneous slant distance of point A.

[0065] For example, the Taylor expansion of point A with reference point as the base can be expressed as:

[0066]

[0067] in, , , , , , respectively, are the multidimensional Taylor expansion coefficients of the corresponding term at point A. , These are the slant distance dependency term and the Doppler center term, respectively. , , All are cross-coupling terms.

[0068] For example, fitting a complex three-dimensional Taylor series with fourth-order parameters yields a simplified quartic term for the slope distance history (i.e., an expression simplified by the multidimensional expansion coefficients). The simplified quartic term for the slope distance history can be expressed as:

[0069]

[0070] in, , , , , The fitting coefficients are the multidimensional Taylor expansion coefficients of the 0th to 4th orders of the instantaneous slope distance of point A.

[0071] For example, a high-precision instantaneous slant range model can be represented as:

[0072]

[0073] in:

[0074]

[0075]

[0076] After simplification, we get:

[0077]

[0078] in, This is the high-precision slope distance of point A.

[0079] It can be seen that the high-precision slant range model decouples the quadratic terms and avoids higher-order terms while meeting imaging accuracy requirements, thus simplifying the subsequent processing. Therefore, simplifying the slant range history through multiple fitting and Taylor expansion can effectively improve the speed and accuracy of subsequent imaging, meeting the high real-time requirements of the glider platform.

[0080] The synthetic aperture radar imaging method for helical trajectory gliders provided in this invention can be applied to electronic devices such as mobile terminals, personal laptops, and supercomputers. This invention does not impose any restrictions on the specific type of electronic device.

[0081] Figure 4 The diagram shown illustrates the implementation flow of a synthetic aperture radar (SAR) imaging method for a helical trajectory glider provided by an embodiment of the present invention. As an example and not a limitation, the SAR imaging method for a helical trajectory glider may include steps S401-S405, and this method can be applied to the aforementioned electronic device. The steps are described below.

[0082] In one possible implementation, the echo signal can be obtained by performing time-domain and frequency-domain compensation processing on the echo signal sequentially based on the time-domain compensation function and the frequency-domain compensation function, respectively, through the following steps S401-S403 to obtain a two-dimensional frequency domain signal.

[0083] S401 uses a time-domain compensation function to perform time-domain consistent compensation processing on the echo signal to obtain a time-domain compensated signal.

[0084] For example, the time-domain compensation function and the frequency-domain compensation function can be constructed based on the relationship between the high-precision instantaneous slant range of any point A in the radar imaging scene and the instantaneous slant range of the reference point.

[0085] In one example, the received echo signal can first be processed by range-to-Fourier transform and range pulse compression to obtain the radar signal. Then, based on the time-domain compensation function, consistency compensation is performed on the radar signal in the azimuth time domain and range frequency domain to obtain the time-domain compensated signal.

[0086] For example, the echo signal can satisfy the following formula:

[0087]

[0088] in, for, The scattering coefficient is... For the distance window function, For azimuth window function, The imaginary unit, For carrier frequency, At the speed of light, To adjust the frequency, For distance and time.

[0089] For example, radar signals can satisfy the following formula:

[0090]

[0091] in, For radar signals, For distance frequency.

[0092] For example, the time-domain compensation function can satisfy the following formula:

[0093]

[0094] in, This is the time-domain compensation function.

[0095] For example, the time-domain compensated signal can satisfy the following formula:

[0096]

[0097] in, This is a time-domain compensated signal.

[0098] S402, based on the stationary phase principle, obtains the echo two-dimensional frequency domain signal from the time-domain compensation signal.

[0099] For example, the echo two-dimensional frequency domain signal can satisfy the following formula:

[0100]

[0101] in, The echo is a two-dimensional frequency domain signal. , For azimuth frequency, , , , , , The parameters are Doppler parameters of the distance history and are all space-varying.

[0102] For example, the coefficients of the second, third, and fourth orders Taylor series expansion yields:

[0103]

[0104] in, , , These are all expansion coefficients of different terms.

[0105] Specifically, , , It is also an expansion coefficient.

[0106] For example, by adjusting the coefficients After expansion and rearrangement, the phase of the two-dimensional frequency domain signal of the echo can satisfy the following formula:

[0107]

[0108] in, This represents the phase of the two-dimensional frequency domain signal of the echo. The first term in the phase expression is a reference term that needs to be removed through subsequent compensation; the second term is the range term; and the third term is the azimuth term.

[0109] S403 uses a frequency domain compensation function to perform consistency compensation on the two-dimensional frequency domain signal of the echo to obtain a two-dimensional frequency domain signal.

[0110] In one example, the frequency domain compensation function can also be a time domain compensation function constructed based on the relationship between the high-precision instantaneous slant range of point A and the instantaneous slant range of the reference point.

[0111] For example, the frequency domain compensation function can satisfy the following formula:

[0112]

[0113] in, This is the frequency domain compensation function.

[0114] In one example, a two-dimensional frequency domain signal can satisfy the following formula:

[0115]

[0116] in, The signal is a two-dimensional frequency domain signal. Compared to the echo two-dimensional frequency domain signal, the reference term has been removed from the two-dimensional frequency domain signal. The reference point in the imaging scene can be focused into the image using the two-dimensional frequency domain signal. However, due to the large coupling spatial variation, the focusing effect at the edge points of the image is poor. Therefore, step S404 is required to remove the remaining coupling spatial variation in the phase.

[0117] S404 performs a non-uniform fast Fourier transform on a two-dimensional frequency domain signal to obtain the transformed two-dimensional frequency domain signal.

[0118] In one example, the coupling space variation in a two-dimensional frequency domain signal can be removed by using a non-uniform fast Fourier transform to obtain the transformed two-dimensional frequency domain signal.

[0119] For example, the process of non-uniform fast Fourier transform can be represented as:

[0120]

[0121] in, The transformed two-dimensional frequency domain signal, For a two-dimensional frequency domain signal, the zeroth order expansion coefficients based on the reference point satisfy: The coefficients of a first-order expansion satisfy: The first frequency domain expansion coefficients satisfy: The second frequency domain expansion coefficients satisfy: , M and N These represent the number of sampling points in the range frequency domain and the azimuth frequency domain, respectively. , .

[0122] For example, the simplified and transformed two-dimensional frequency domain signal can satisfy the following formula:

[0123]

[0124] in, The transformed signal of the two-dimensional frequency domain signal with respect to m and n. , These are two expansion coefficients.

[0125] S405 performs an inverse Fourier transform on the transformed two-dimensional frequency domain signal to obtain a focused image.

[0126] In one example, a two-dimensional fast Fourier transform can be performed on the transformed two-dimensional frequency domain signal, and then SAR imaging can be performed to obtain a focused image of the aircraft.

[0127] Since the high-precision instantaneous slant range model provided by this invention is constructed based on a helical trajectory geometric model, it fully considers the velocity and acceleration changes of an aircraft moving along a helical trajectory. Therefore, by constructing a compensation function using the high-precision instantaneous slant range of the aircraft and using this compensation function to compensate for the echo signal, the compensation effect of the compensation function can be improved, thereby improving the imaging quality of the helical trajectory. Removing coupling spatial variation errors in the phase using non-uniform fast Fourier transform can also improve the imaging quality and accuracy. Furthermore, determining the high-precision instantaneous slant range of the observed object using the high-precision instantaneous slant range model obtained through Taylor expansion and multiple fitting simplifications can reduce the amount of computation and enhance real-time performance.

[0128] Figure 5 The diagram shown illustrates the structure of a synthetic aperture radar imaging device for a helical trajectory glider provided in an embodiment of the present invention. As an example and not a limitation, the device 500 may include a compensation module 510 and a Fourier transform module 520.

[0129] The compensation module 510 is used to perform time-domain and frequency-domain compensation processing on the echo signal sequentially using time-domain compensation function and frequency-domain compensation function to obtain a two-dimensional frequency domain signal;

[0130] The time-domain compensation function and the frequency-domain compensation function are constructed based on the relationship between the high-precision instantaneous slant range of any point in the imaging scene and the instantaneous slant range of the reference point. The instantaneous slant range is determined based on the geometric model of a spiral trajectory with rapid acceleration and velocity changes.

[0131] The Fourier transform module 520 is used to perform a non-uniform fast Fourier transform on the two-dimensional frequency domain signal to obtain the transformed two-dimensional frequency domain signal; and to perform an inverse Fourier transform on the transformed two-dimensional frequency domain signal to obtain the focused image of the aircraft.

[0132] To better illustrate the beneficial effects of the present invention, the following simulation experiments were conducted:

[0133] For example, simulation experiments can be conducted using the parameters in Table 1 below to obtain results as follows: Figure 6 The image shown is of the imaging scene.

[0134] Table 1

[0135]

[0136] For example, Figure 6 The vertical axis represents the orientation dimension, and the horizontal axis represents the distance dimension. See also Figure 6 The imaging image shown in (a) and Figure 6 As shown in (b) of the image, the point target interpolation diagram shows that the nine target points in different positions in the imaging scene can be clearly distinguished.

[0137] Therefore, since the high-precision instantaneous slant range model provided by this invention is constructed based on the geometric model of a spiral trajectory, it fully considers the speed and acceleration changes of an aircraft moving in a spiral trajectory. Thus, by constructing a compensation function using the high-precision instantaneous slant range of the aircraft and compensating for the echo signal using this compensation function, the compensation effect of the compensation function can be improved, thereby improving the imaging quality of the spiral trajectory. Removing the coupling spatial variation error in the phase through non-uniform fast Fourier transform can also improve the imaging quality and accuracy.

[0138] Figure 7 The diagram shown is a structural schematic of an electronic device provided in an embodiment of the present invention. Figure 7 The illustrated electronic device 700 may include: at least one processor 710 ( Figure 7 The diagram shows only one processor, a memory 720, and a computer program 730 stored in the memory 720 and executable on the at least one processor 710, which, when executing the computer program 730, implements the steps in any of the above method embodiments.

[0139] The electronic device 700 can be a robot or other processing device capable of implementing the above methods. This embodiment of the invention does not impose any restrictions on the specific type of electronic device.

[0140] Those skilled in the art will understand that Figure 7 This is merely an example of electronic device 700 and does not constitute a limitation on the electronic device. It may include more or fewer components than shown, or combine certain components, or use different components. For example, the electronic device 700 may also include input / output interfaces.

[0141] The processor 710 may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASTCs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0142] In some embodiments, the memory 720 may be an internal storage unit, such as a hard disk or RAM. In other embodiments, the memory 720 may be an external storage device, such as a plug-in hard disk, a smart memory card (SMC), a secure digital card (SD), or a flash card. Furthermore, the memory 720 may include both internal and external storage units. The memory 720 is used to store the operating system, applications, a boot loader, data, and other programs, such as the program code of the computer program. The memory 720 can also be used to temporarily store data that has been output or will be output.

[0143] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0144] Those skilled in the art will understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the functions described above can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this invention. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0145] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0146] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in 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 implementations should not be considered beyond the scope of this invention.

Claims

1. A synthetic aperture radar imaging method for a helical trajectory glider, characterized in that, include: The echo signal is processed sequentially in the time domain and frequency domain by time domain compensation function and frequency domain compensation function to obtain a two-dimensional frequency domain signal; The time-domain compensation function and the frequency-domain compensation function are constructed based on the relationship between the high-precision instantaneous slant range of any point in the imaging scene and the instantaneous slant range of the reference point. The instantaneous slant range is determined based on a geometric model of a spiral trajectory with rapid acceleration and velocity changes. The two-dimensional frequency domain signal is subjected to a non-uniform fast Fourier transform to obtain the transformed two-dimensional frequency domain signal. The inverse Fourier transform of the transformed two-dimensional frequency domain signal is used to obtain the focused image; The high-precision instantaneous slant range is determined based on a high-precision instantaneous slant range model, which is obtained by fitting and simplifying the multidimensional Taylor expansion coefficients of the instantaneous slant range. The high-precision instantaneous slant range model satisfies the following formula: Let A be the high-precision instantaneous slant distance of any point A within the imaging scene. The instantaneous slope distance of the reference point C. For location, slow time; in: , , , , These are the fitting coefficients of the multidimensional Taylor expansion coefficients for the 0th to 4th orders of the instantaneous slope distance of point A. The Taylor expansion coefficients of the instantaneous slant distance at the reference point C are given. , The Taylor expansion coefficients of the instantaneous slant distance of point A are given, wherein the multidimensional Taylor expansion coefficients are obtained by Taylor expansion based on the reference point. in: in, Let be the integration constant. This is the initial platform height. The angle between the velocity vector component in the yaw plane and the polar radius. Angular velocity of rotation The initial velocity is vertical. This is the vertical acceleration.

2. The method according to claim 1, characterized in that, The simplified multidimensional Taylor expansion coefficients satisfy the following formula: in, Let be the multidimensional Taylor expansion coefficient of point A.

3. The method according to claim 1, characterized in that, The process of sequentially compensating the echo signal in the time and frequency domains using time-domain and frequency-domain compensation functions to obtain a two-dimensional frequency domain signal includes: The echo signal is obtained by performing time-domain consistent compensation processing on the time-domain compensation function to obtain a time-domain compensated signal. Based on the stationary phase principle, the echo two-dimensional frequency domain signal is obtained from the time-domain compensation signal; The two-dimensional frequency domain signal is obtained by performing frequency domain consistency compensation processing on the echo two-dimensional frequency domain signal using the frequency domain compensation function.

4. The method according to claim 3, characterized in that, The time-domain compensation function satisfies the following formula: in, The time-domain compensation function is... The imaginary unit, For carrier frequency, For distance frequency, Represents the speed of light; The time-domain compensation signal satisfies the following formula: in, The time-domain compensated signal, The scattering coefficient is... For the distance window function, This is the azimuth window function.

5. The method according to claim 4, characterized in that, The frequency domain compensation function satisfies the following formula: in, The frequency domain compensation function is... , For azimuth frequency, is the expansion factor.

6. The method according to claim 5, characterized in that, The process of the non-uniform fast Fourier transform is represented as follows: in, The transformed two-dimensional frequency domain signal, For the two-dimensional frequency domain signal, These are the expansion coefficients in the first frequency domain. The zeroth order expansion coefficients are based on the reference point. These are the expansion coefficients in the second frequency domain. These are the first-order expansion coefficients based on the reference point.

7. A synthetic aperture radar imaging device for a helical trajectory glider, characterized in that, include: The compensation module is used to perform time-domain and frequency-domain compensation processing on the echo signal sequentially using a time-domain compensation function and a frequency-domain compensation function to obtain a two-dimensional frequency-domain signal. The time-domain compensation function and the frequency-domain compensation function are constructed based on the relationship between the high-precision instantaneous slant range of any point in the imaging scene and the instantaneous slant range of the reference point. The instantaneous slant range is determined based on a geometric model of a spiral trajectory with rapid acceleration and velocity changes. The Fourier transform module is used to perform a non-uniform fast Fourier transform on the two-dimensional frequency domain signal to obtain a transformed two-dimensional frequency domain signal; and to perform an inverse Fourier transform on the transformed two-dimensional frequency domain signal to obtain a focused image of the aircraft. The high-precision instantaneous slant range is determined based on a high-precision instantaneous slant range model, which is obtained by fitting and simplifying the multidimensional Taylor expansion coefficients of the instantaneous slant range. The high-precision instantaneous slant range model satisfies the following formula: Let A be the high-precision instantaneous slant distance of any point A within the imaging scene. The instantaneous slope distance of the reference point C. For location, slow time; in: , , , , These are the fitting coefficients of the multidimensional Taylor expansion coefficients for the 0th to 4th orders of the instantaneous slope distance of point A. The Taylor expansion coefficients of the instantaneous slant distance at the reference point C are given. , The Taylor expansion coefficients of the instantaneous slant distance of point A are given, wherein the multidimensional Taylor expansion coefficients are obtained by Taylor expansion based on the reference point. in: in, Let be the integration constant. This is the initial platform height. The angle between the velocity vector component in the yaw plane and the polar radius. Angular velocity of rotation The initial velocity is vertical. This is the vertical acceleration.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1-6.

Images