Three-dimensional imaging method and device for interferometric inverse synthetic aperture radar in squint scene

Abstract

The invention provides a three-dimensional imaging method and device of an interferometric inverse synthetic aperture radar in a squint scene. The method comprises the following steps: respectively carrying out pulse compression processing on echo signals obtained by a right-angle L-shaped three-antenna system, and sequentially carrying out fast Fourier transform and HHO algorithm processing on correspondingly obtained pulse compression echo data to obtain motion parameters of a target; constructing a dynamic virtual antenna according to the motion parameters of the target, the pulse compression echo data, the distance prior information and the angle prior information; performing strabismus compensation on the pulse compression echo data by calculating the dynamic baseline length and the time-varying strabismus wave path difference of the dynamic virtual antenna to obtain compensation echo data of each antenna in the right-angle L-shaped three-antenna system; performing translational motion compensation on the compensation echo data by using the motion parameters of the target to obtain a high-resolution ISAR image of each antenna about the target; and obtaining a three-dimensional imaging result of the interferometric inverse synthetic aperture radar in a squint scene through the high-resolution ISAR image.

Description

Technical Field

[0001] The present invention relates to the field of radar imaging technology, and in particular to a three-dimensional imaging method and device of an interferometric inverse synthetic aperture radar in a squint scene. Background Art

[0002] As an important development direction in the field of radar, radar three-dimensional imaging technology aims to make up for the limitations of inverse synthetic aperture radar (ISAR) in target recognition and improve the target recognition and detection capabilities of radar systems. The interferometric inverse synthetic aperture radar system (InISAR) is based on the principle of multi-antenna ISAR imaging and realizes three-dimensional reconstruction of the target through interferometric measurement technology. This technology is widely used in military reconnaissance, civilian monitoring and other fields, and is of great significance for improving the comprehensive performance of radar systems. Among them, the three-antenna configured InISAR is favored because of its simple structure and small number of antennas. Under ideal conditions, that is, when the target is near the antenna electrical axis (facing the scene), the projection coordinates of different baseline estimates are perpendicular to each other, and the three-dimensional geometric structure of the target can be accurately reconstructed.

[0003] However, in practical applications, due to the non-cooperative nature of the imaging target, the target is often in a squint scene far away from the antenna electrical axis, which poses a severe challenge to the existing InISAR imaging methods. In order to cope with the problem of InISAR three-dimensional imaging in squint scenes, researchers have proposed a variety of solutions in recent years. Among them, the nonlinear least squares (NLS) method and the squint iterative improvement (SII) algorithm are two representative squint InISAR imaging solutions. Both methods are committed to eliminating the squint additional phase to accurately obtain the coordinate values ​​of the target scattering points along the baseline direction. Through coordinate transformation, the true coordinates of the target scattering points can be further obtained, thereby realizing three-dimensional imaging.

[0004] Although the above two methods have achieved certain results in InISAR imaging in squint scenes, there are still some shortcomings. First, both methods aim to eliminate the additional phase, and require multiple iterations to complete the imaging process, resulting in low imaging efficiency. Secondly, since a large number of approximate processing is used in the method, error transmission problems may be introduced, affecting the imaging accuracy. Therefore, how to achieve efficient and accurate InISAR three-dimensional imaging in squint scenes is still a technical problem that needs to be solved in the current radar imaging field. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a three-dimensional imaging method and device of interferometric inverse synthetic aperture radar in a squint scene.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a three-dimensional imaging method of an interferometric inverse synthetic aperture radar in a squint scene, which is applied to a right-angle L-configuration three-antenna system, comprising:

[0008] The echo signals acquired by the right-angle L-configuration three-antenna system are pulse compressed to obtain pulse compression echo data;

[0009] The pulse compression echo data is processed by fast Fourier transform, and the translation motion parameters are estimated based on the result of fast Fourier transform processing and Harris Hawk optimization HHO algorithm to obtain the motion parameters of the target;

[0010] A dynamic virtual antenna is constructed based on the target's motion parameters, pulse compression echo data, distance prior information, and angle prior information;

[0011] By calculating the dynamic baseline length and time-varying squint path difference of the dynamic virtual antenna, squint compensation is performed on the pulse compression echo data to obtain the compensated echo data of each antenna in the right-angle L-configuration three-antenna system.

[0012] The motion parameters of the target are used to perform translational motion compensation on the compensated echo data, and a high-resolution ISAR image of the target for each antenna is obtained.

[0013] The three-dimensional imaging results of interferometric inverse synthetic aperture radar in the squint scene are obtained based on high-resolution ISAR images.

[0014] Optionally, the right-angle L-configuration three-antenna system includes: a first antenna, a second antenna, and a third antenna;

[0015] The first antenna is a transceiver integrated antenna, the second antenna and the third antenna are both receiving antennas, and the first antenna is the coordinate origin of the right-angle L-configuration three-antenna system.

[0016] Optionally, the pulse compression echo data is subjected to fast Fourier transform processing, and translational motion parameters are estimated based on the result of the fast Fourier transform processing and the Harris Hawk optimized HHO algorithm to obtain the motion parameters of the target, including:

[0017] Performing fast Fourier transform processing on the pulse compression echo data of the first antenna to obtain first echo transform data;

[0018] Perform polynomial modeling on the target's motion process to obtain the target scene model;

[0019] Based on the first echo transform data and the HHO algorithm under the target scene model, the translation motion parameters of the target are estimated to obtain the motion parameters of the target.

[0020] Optionally, the dynamic baseline length of the dynamic virtual antenna is expressed as:

[0021]

[0022] L X represents the dynamic baseline length, L1 represents the distance between the first antenna and the second antenna, θ X represents the angle between the target and the x-axis at the initial moment, R(t m ) represents the slow time moment t m The distance between the rotation center of the target and the first antenna when the target moves, wherein the dynamic baseline length represents the distance between the first antenna and the dynamic virtual antenna during the target movement;

[0023] The time-varying slant path difference of the dynamic virtual antenna is expressed as:

[0024]

[0025] BB″ represents the time-varying squint path difference, wherein the time-varying squint path difference represents the distance between the second antenna and the dynamic virtual antenna.

[0026] Optionally, by calculating the dynamic baseline length and the time-varying squint path difference of the dynamic virtual antenna, squint compensation is performed on the pulse compression echo data to obtain the compensated echo data of each antenna in the right-angle L-configuration three-antenna system, including:

[0027] Convolution processing is performed on the phase corresponding to the time-varying squint path difference and the pulse compression echo data of the second antenna and the third antenna, respectively, to obtain the second compensation echo data and the third compensation echo data after squint compensation;

[0028] The pulse compression echo data of the first antenna, the second compensation echo data and the third compensation echo data together constitute the compensation echo data of the right-angle L-configuration three-antenna system.

[0029] Optionally, a three-dimensional imaging result of an interferometric inverse synthetic aperture radar in a squint scene is obtained based on the high-resolution ISAR image, including:

[0030] The high-resolution ISAR images of all antennas are modulo-added to obtain a composite image;

[0031] Perform image registration on the high-resolution ISAR image according to the entropy of the synthetic image to obtain a high-resolution ISAR registered image;

[0032] The high-resolution ISAR registered images are interferometrically processed to obtain three-dimensional imaging results.

[0033] Optionally, performing image registration on the high-resolution ISAR image according to the entropy of the synthetic image to obtain a high-resolution ISAR registered image includes:

[0034] Image registration of high-resolution ISAR images using HHO algorithm and synthetic images;

[0035] When the change in entropy of the synthetic image is less than a preset threshold, a high-resolution ISAR registration image is obtained.

[0036] In a second aspect, the present invention provides a three-dimensional imaging device of an interferometric inverse synthetic aperture radar in a squint scene, which is applied to a right-angle L-configuration three-antenna system, including: a pulse compression unit, a parameter estimation unit, a virtual construction unit, a compensation unit, and an image generation unit;

[0037] The pulse compression unit is used to: perform pulse compression processing on the echo signals obtained by the right-angle L-configuration three-antenna system to obtain pulse compression echo data;

[0038] The parameter estimation unit is used to: perform fast Fourier transform processing on the pulse compression echo data, perform translation motion parameter estimation based on the result of fast Fourier transform processing and Harris Hawk Optimization HHO algorithm, and obtain the motion parameters of the target;

[0039] The virtual construction unit is used to: construct a dynamic virtual antenna according to the target's motion parameters, pulse compression echo data, distance prior information, and angle prior information;

[0040] The compensation unit is used to: perform squint compensation on the pulse compression echo data by calculating the dynamic baseline length and time-varying squint path difference of the dynamic virtual antenna, and obtain the compensated echo data of each antenna in the right-angle L-configuration three-antenna system; perform translational motion compensation on the compensated echo data using the motion parameters of the target, and obtain the high-resolution ISAR image of each antenna about the target;

[0041] The image generation unit is used to obtain the three-dimensional imaging result of the interferometric inverse synthetic aperture radar in the squint scene based on the high-resolution ISAR image.

[0042] In a third aspect, the present invention provides a three-dimensional imaging device of an interferometric inverse synthetic aperture radar in an oblique viewing scene, comprising: a processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor. When the three-dimensional imaging device of the interferometric inverse synthetic aperture radar in an oblique viewing scene is running, the processor and the storage medium communicate via the bus, and the processor executes the machine-readable instructions to perform the steps of the three-dimensional imaging method of the interferometric inverse synthetic aperture radar in an oblique viewing scene as described in the first aspect above.

[0043] The present invention provides a three-dimensional imaging method and device of an interferometric inverse synthetic aperture radar in a squint scene. Among them, a three-dimensional imaging method of an interferometric inverse synthetic aperture radar in a squint scene includes: performing pulse compression processing on the echo signals obtained by the right-angle L-configuration three-antenna system respectively to obtain pulse compression echo data; performing fast Fourier transform processing on the pulse compression echo data, and estimating translational motion parameters based on the result of the fast Fourier transform processing and the Harris Hawk optimization HHO algorithm to obtain the motion parameters of the target; constructing a dynamic virtual antenna according to the motion parameters of the target, pulse compression echo data, distance prior information and angle prior information; performing squint compensation on the pulse compression echo data by calculating the dynamic baseline length and time-varying squint path difference of the dynamic virtual antenna to obtain the compensated echo data of each antenna in the right-angle L-configuration three-antenna system; performing translational motion compensation on the compensated echo data using the motion parameters of the target to obtain a high-resolution ISAR image of each antenna about the target; and obtaining the three-dimensional imaging result of the interferometric inverse synthetic aperture radar in the squint scene based on the high-resolution ISAR image. In the present invention, by constructing a dynamic virtual antenna and calculating the time-varying squint path difference, InISAR three-dimensional imaging in a squint scene is realized, and the imaging quality is improved; the HHO algorithm is used to estimate the translation motion parameters, and the accuracy and stability of the parameter estimation are improved; finally, the high-resolution ISAR images of each antenna are fused through the image registration technology, and the accuracy of the three-dimensional imaging results of the interferometric inverse synthetic aperture radar in the squint scene is improved.

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic flow chart of a three-dimensional imaging method of an interferometric inverse synthetic aperture radar in a squint scene provided by an embodiment of the present invention;

[0046] Figure 2 The schematic diagram of the structure of the target scene model is shown exemplarily;

[0047] Figure 3 The structural schematic diagram of the ship scattering point model is shown exemplarily;

[0048] Figure 4 : is an actual scene diagram of a right-angle L-configuration three-antenna system shown as an example;

[0049] Figure 5 The three-dimensional imaging result of the interferometric inverse synthetic aperture radar at a squint angle of 30° is shown as an example;

[0050] Figure 6 The three-dimensional imaging result of the interferometric inverse synthetic aperture radar at a squint angle of 45° is shown as an example;

[0051] Figure 7 The three-dimensional imaging result of the interferometric inverse synthetic aperture radar at a squint angle of 60° is shown as an example;

[0052] Figure 8 A schematic structural diagram of a three-dimensional imaging device of an interferometric inverse synthetic aperture radar in a squint scene provided by an embodiment of the present invention;

[0053] Fig. 9 A schematic structural diagram of a three-dimensional imaging device of an interferometric inverse synthetic aperture radar in a squint scene provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0055] In order to improve the accuracy of three-dimensional imaging results of interferometric inverse synthetic aperture radar in a squint scene, an embodiment of the present invention provides a three-dimensional imaging method of interferometric inverse synthetic aperture radar in a squint scene. Figure 1 The present invention provides a flow chart of a three-dimensional imaging method of an interferometric inverse synthetic aperture radar in a squint scene. Figure 1 As shown, including:

[0056] S101 , performing pulse compression processing on echo signals acquired by the right-angle L-configuration three-antenna system to obtain pulse compression echo data.

[0057] Wherein, the right-angle L-configuration three-antenna system includes: a first antenna, a second antenna and a third antenna;

[0058] The first antenna is a transceiver integrated antenna, the second antenna and the third antenna are both receiving antennas, and the first antenna is the coordinate origin of the right-angle L-configuration three-antenna system.

[0059] In the embodiment of the present invention, the first antenna is used as the coordinate origin of the right-angle L-configuration three-antenna system, which can facilitate the unification of system layout and calibration as well as consistency and repeatability, etc. It is helpful to optimize system performance and improve the accuracy and real-time performance of signal processing.

[0060] S102, performing fast Fourier transform processing on the pulse compression echo data, and estimating translational motion parameters based on the result of the fast Fourier transform processing and the Harris Hawk Optimization (HHO) algorithm to obtain the motion parameters of the target.

[0061] Optionally, S102 may specifically include:

[0062] Performing fast Fourier transform processing on the pulse compression echo data of the first antenna to obtain first echo transform data;

[0063] Perform polynomial modeling on the target's motion process to obtain the target scene model;

[0064] Based on the first echo transform data and the HHO algorithm under the target scene model, the translation motion parameters of the target are estimated to obtain the motion parameters of the target.

[0065] It should be noted that since the first antenna is a transceiver antenna, there is a direct correspondence between the signal it transmits and the echo signal received. This correspondence makes it more direct and accurate to extract the target's motion information from the echo data of the first antenna. In addition, in radar signal processing, simultaneous processing of echo data from multiple antennas may increase the complexity and time cost of calculation, especially in application scenarios with high real-time requirements, this complexity may become a bottleneck for system performance. By processing only the echo data of the first antenna, the complexity of signal processing can be reduced while ensuring a certain degree of accuracy, and the real-time performance and efficiency of the system can be improved. Finally, in a right-angle L-configuration three-antenna system, although each antenna may receive an echo signal from the target, these signals may contain redundant target motion information. By processing only the echo data of the first antenna and combining it with the HHO algorithm, sufficient target motion information can be extracted without the need to process the echo data of multiple antennas simultaneously.

[0066] In addition, the motion parameters of the target may include speed information and acceleration information of the target.

[0067] S103: construct a dynamic virtual antenna according to the target's motion parameters, pulse compression echo data, distance prior information, and angle prior information.

[0068] Specifically, in this embodiment, a dynamic virtual antenna is constructed under a target scene model according to the motion parameters of the target, pulse compression echo data, distance prior information, and angle prior information.

[0069] Figure 2 The schematic diagram of the structure of the target scene model is shown as an example. Figure 2 As shown, O-XYZ is the coordinate system of the right-angle L-configuration three-antenna system. The first antenna A (0, 0, 0) is located at the coordinate origin O, the second antenna B (L1, 0, 0) and the third antenna C (0, 0, L2) are located in the X-axis and Z-axis respectively, and L1 and L2 are the baseline lengths in the horizontal and vertical directions respectively. Specifically, L1 represents the distance between the first antenna and the second antenna, and L2 represents the distance between the first antenna and the third antenna. O′ is the rotation center of the target, and the O′-UVW coordinate system is constructed with O′ as the origin. During the radar observation time t0~t m (t0 is the initial time, t mIn the far field in the XOY plane (slow time), the target moves from position 1 (solid line target position O' in the figure) to position 2 (dashed line target position O" in the figure). Figure 2 In the above equation, P is a scattering point in the target, which follows the target from P′ to P″. Assume that during the movement, at the slow time t m At this moment, the coordinates of the scattering point P are (U P ,V P ,W P ), whose coordinate in the O-XYZ coordinate system is P(X P ,Y P ,Z P ).

[0070] Extend O′B and O″B to intersect the U′ axis at B′ and B″ respectively. Assume that there is a dynamic virtual antenna B′ in the U axis. As the target moves, the position of the dynamic virtual antenna B′ also moves from B′ to B″. At this time, the L-shaped array composed of antennas AB′C will meet the far-field normal view condition when performing InISAR three-dimensional imaging of the target. At this time, draw an auxiliary line BD′ perpendicular to AO′, and the length of the distance BD′ between the second antenna and the V axis and the distance AB′ between the first antenna and the virtual antenna at time t0 can be calculated:

[0071]

[0072] Among them, θ X It represents the angle between the target and the x-axis at the initial moment, L1 represents the distance between the first antenna and the second antenna, and R0 represents the initial slant range of the target.

[0073] Since the coherent accumulation angle of ISAR imaging is small (3° to 5°), in this embodiment, it can be approximately considered that at the slow time t m At this moment, the line AO″ between the first antenna and the target rotation center is perpendicular to the line AB″ between the first antenna and the virtual antenna, ∠D″AB≈θ X . Further, add an auxiliary line BD″ so that BD″ is perpendicular to AO″, and then we can get t m The length of the distance BD″ between the second antenna and the V axis and the distance AB″ between the first antenna and the virtual antenna at time:

[0074]

[0075] R(t m ) represents the slow time moment t m The dynamic baseline length represents the distance between the first antenna and the dynamic virtual antenna during the target movement.

[0076] S104, by calculating the dynamic baseline length and the time-varying squint path difference of the dynamic virtual antenna, squint compensation is performed on the pulse compression echo data to obtain compensated echo data of each antenna in the right-angle L-configuration three-antenna system.

[0077] In the above formula, R(t m )=R0+ΔR(t m ), when t=t0, R(t m )=R0. Combining the above formula, the dynamic baseline length L along the U′ axis is X It can be expressed as L X .

[0078] Optionally, the dynamic baseline length of the dynamic virtual antenna is expressed as:

[0079]

[0080] L X represents the dynamic baseline length, L1 represents the distance between the first antenna and the second antenna, θ X represents the angle between the target and the x-axis at the initial moment, R(t m ) represents the slow time moment t m The distance between the rotation center of the target and the first antenna when the target moves, wherein the dynamic baseline length represents the distance between the first antenna and the dynamic virtual antenna during the target movement;

[0081] The time-varying slant path difference of the dynamic virtual antenna is expressed as:

[0082]

[0083] BB″ represents the time-varying squint path difference, wherein the time-varying squint path difference represents the distance between the second antenna and the dynamic virtual antenna.

[0084] In summary, the overall process is: obtain the distance prior information R0 and the angle prior information θ through the traditional right-angle L-configuration three-antenna system X Then, the target motion parameters are obtained. Then, R(t m ). Finally, calculate the dynamic baseline length L X Then through L X Calculate the time-varying squint path difference BB″. Taking antenna pair AB as an example, the squint compensation can be completed by compensating the phase corresponding to the time-varying squint path difference BB″ in the echo data of antenna B.

[0085] Optionally, S104 may specifically include:

[0086] Convolution processing is performed on the phase corresponding to the time-varying squint path difference and the pulse compression echo data of the second antenna and the third antenna, respectively, to obtain the second compensation echo data and the third compensation echo data after squint compensation;

[0087] The pulse compression echo data of the first antenna, the second compensation echo data and the third compensation echo data together constitute the compensation echo data of the right-angle L-configuration three-antenna system.

[0088] S105 , using the motion parameters of the target to perform translational motion compensation on the compensated echo data, and obtaining a high-resolution ISAR image of the target for each antenna.

[0089] Exemplarily, the echo of the first antenna after translational motion compensation, that is, the high-resolution ISAR image of the first antenna with respect to the target can be expressed as:

[0090]

[0091] Represents the estimated value of the target-based motion parameters when the first antenna is in the hth range-frequency unit and the kth slow time The echo obtained after translation motion compensation, M represents the total number of pulses, N represents the total number of range units, m represents the mth slow time, n represents the range frequency unit, -N / 2≤n≤N / 2-1, 0≤m≤M-1; j represents the imaginary unit, S A (n; m) represents the total echo signal of the first antenna about the target, c represents the transmission speed of the echo, Δf r Represents the distance frequency, f c Indicates the carrier frequency, represents the coefficient of the lth order term, L represents the total number of orders, Δt m represents the slow time sampling interval, Represents the estimated values ​​of the motion parameters of the target.

[0092] The echo of the second antenna after translational motion compensation, that is, the high-resolution ISAR image of the second antenna about the target can be expressed as:

[0093]

[0094] represents the echo of the second antenna after translational motion compensation, σ PB represents the backscattering coefficient of the scattering point P with respect to the second antenna, σ PA represents the backscattering coefficient of the scattering point P with respect to the first antenna, represents the ideal ISAR echo signal of the first antenna, R B,WPD (·) represents the time-varying path difference of strabismus that needs to be compensated.

[0095] Adaptively, the echo of the third antenna after translational motion compensation can correspond to On the basis of , adaptive replacement is performed, that is, the parameters of the second antenna are replaced with the parameters of the third antenna.

[0096] S106. Obtain three-dimensional imaging results of interferometric inverse synthetic aperture radar in a squint scene based on the high-resolution ISAR image.

[0097] Specifically, in the above-mentioned interference processing process, it is necessary to first extract strong scattering points of the high-resolution ISAR registration image, and perform interference processing on the high-resolution ISAR registration image based on the strong scattering points. The extraction of strong scattering points can be performed based on a peak extraction algorithm.

[0098] In the embodiment of the present invention, the three-dimensional imaging result before rotation can be expressed as:

[0099]

[0100] Among them, U P represents the coordinate of the scattering point P on the U′ axis, V P represents the coordinate of the scattering point P on the V′ axis, W P represents the coordinate of the scattering point P on the W′ axis, represents the phase obtained after the echo of the virtual antenna interferes with the echo of the first antenna, R0 represents the initial slant range, n P Indicates the distance unit number of the scattering point P, -N / 2≤n P ≤N / 2-1, f s represents the fast-time sampling frequency, represents the phase obtained after the echo of the first antenna interferes with the echo of the third antenna, and L2 represents the distance between the first antenna and the third antenna.

[0101] Furthermore, after obtaining the three-dimensional imaging result before rotation, it is also necessary to convert U P 、V P and W P The scattering point coordinate matrix is ​​rotated by θ X After obtaining the angle prior information, the three-dimensional imaging result of the interferometric inverse synthetic aperture radar in the squint scene is finally obtained.

[0102] The embodiment of the present invention provides a three-dimensional imaging method of an interferometric inverse synthetic aperture radar in a squint scene, comprising: performing pulse compression processing on echo signals obtained by a right-angle L-configuration three-antenna system respectively to obtain pulse compression echo data; performing fast Fourier transform processing on the pulse compression echo data, and estimating translational motion parameters based on the result of the fast Fourier transform processing and a Harris Hawk optimization HHO algorithm to obtain motion parameters of a target; constructing a dynamic virtual antenna according to the motion parameters of the target, the pulse compression echo data, distance prior information, and angle prior information; performing squint compensation on the pulse compression echo data by calculating the dynamic baseline length and time-varying squint path difference of the dynamic virtual antenna to obtain compensated echo data of each antenna in the right-angle L-configuration three-antenna system; performing translational motion compensation on the compensated echo data using the motion parameters of the target to obtain a high-resolution ISAR image of each antenna about the target; and obtaining a three-dimensional imaging result of the interferometric inverse synthetic aperture radar in the squint scene based on the high-resolution ISAR image. In the embodiment of the present invention, by constructing a dynamic virtual antenna and calculating the time-varying squint path difference, InISAR three-dimensional imaging in a squint scene is achieved, and the imaging quality is improved; the HHO algorithm is used to estimate the translation motion parameters, and the accuracy and stability of the parameter estimation are improved; finally, the high-resolution ISAR images of each antenna are fused through the image registration technology, and the accuracy of the three-dimensional imaging results of the interferometric inverse synthetic aperture radar in the squint scene is improved.

[0103] Optionally, S106 may specifically include:

[0104] The high-resolution ISAR images of all antennas are modulo-added to obtain a composite image;

[0105] Perform image registration on the high-resolution ISAR image according to the entropy of the synthetic image to obtain a high-resolution ISAR registered image;

[0106] The high-resolution ISAR registered images are interferometrically processed to obtain the three-dimensional imaging results of interferometric inverse synthetic aperture radar in the squint scene.

[0107] It should be noted that, in the process of interference processing, it is necessary to first extract the strong scattering points of the high-resolution ISAR registration image, and perform interference processing on the high-resolution ISAR registration image based on the strong scattering points to obtain a three-dimensional imaging result.

[0108] Optionally, performing image registration on the high-resolution ISAR image according to the entropy of the synthetic image to obtain a high-resolution ISAR registered image includes:

[0109] Image registration of high-resolution ISAR images using HHO algorithm and synthetic images;

[0110] When the change in entropy of the synthetic image is less than a preset threshold, a high-resolution ISAR registration image is obtained.

[0111] In order to verify the effectiveness of the three-dimensional imaging method of interferometric inverse synthetic aperture radar in a squint scene provided by an embodiment of the present invention, a simulation experiment was also conducted. The following is a diagram:

[0112] The ship scattering point model is constructed using the publicly available length, width and height data of a destroyer. Figure 3 .like Figure 3 As shown in Figure 1, the model contains 51 scattering points with a size of 155m×120.4m×33.3m. Assume that the scattering coefficient of each scattering point in the model is 1. Figure 2 and Figure 4 The main simulation parameters of the right-angle L-configuration three-antenna InISAR system are shown in Table 1. The experimental operation system is Intel(R) Core(TM) i5-13400F@2.50GHz and NVIDIA GeForceRTX 4060GPU, 64-bit Windows10 operating system, and the simulation software is MATLAB, version R2024a.

[0113] Table 1 Main simulation parameters of InISAR system

[0114] parameter Numeric parameter Numeric <![CDATA[Baseline L1]]> 4m <![CDATA[Baseline L2]]> 4m Carrier frequency 10GHz bandwidth 200MHz PRF 400Hz Target distance 30Km Pulse Width 2us Sampling frequency 240MHz Number of distance units 960 Number of azimuth units 512

[0115] Implementation steps: Set the initial oblique angle of the ship target to 30°, and the translation speed, acceleration and movement direction of the ship target to: 20m / s, 5m / s2, 45°. Figure 4 The figure is an actual scene diagram of a right-angle L-configuration three-antenna system as an example. Figure 4 The antenna A, antenna B and antenna C correspond to the first antenna, the second antenna and the third antenna respectively. The above-mentioned squint angle is the angle formed by the line formed by the target rotation center and the first antenna and the X-axis, and the movement direction is the angle between the target speed direction and the X-axis. At the same time, in order to simulate the yaw motion of the target, the rotation speed of the three-dimensional model around the Z-axis is set to 0.1rad / s. In order to verify the effectiveness and robustness of the proposed method, additive complex Gaussian white noise is added to the echo of each antenna so that the signal-to-noise ratio of the signal is 10dB. Finally, after processing based on the method of the present invention, the three-dimensional imaging result of the interferometric inverse synthetic aperture radar in the squint scene is as shown in the attached figure. Figure 5-7 shown. Specifically, Figure 5 The following is an example of the three-dimensional imaging result of the interferometric inverse synthetic aperture radar at a squint angle of 30°. Figure 6 The following is an example of the three-dimensional imaging result of the interferometric inverse synthetic aperture radar at a 45° oblique viewing angle. Figure 7 The three-dimensional imaging result of the interferometric inverse synthetic aperture radar at a squinting angle of 60° is shown as an example. Figure 5 , Figure 5 The image on the left in the middle represents a three-dimensional view of the three-dimensional imaging result, and the results on the right are, from top to bottom, the range-azimuth profile, the height-range profile, and the height-azimuth profile of the left image. Figure 5 Result in the figure represents the three-dimensional imaging result, i.e., the three-dimensional coordinates of the scattering points reconstructed based on the method of the present invention, and Model represents the real three-dimensional coordinates of the scattering points in the model. The blue X, Y, and Z represent the three-dimensional coordinates of the reconstructed scattering points obtained based on the method of the present invention indicated by the blue arrows in the shape of *, and the red X, Y, and Z represent the three-dimensional coordinates of the scattering points in the real model indicated by the red arrows in the shape of circles. Figure 6 and Figure 7 and Figure 5 The interpretation of the corresponding elements in is the same. Figure 5-Figure 7 It can be seen that the reconstructed three-dimensional imaging result obtained based on the method of the present invention is highly consistent with the real model and has a small deviation, which verifies that the method of the present invention has high imaging accuracy.

[0116] In order to quantitatively describe the performance of the method of the present invention, the root mean square error (RMSE) between the reconstructed scattering point coordinates and the ideal three-dimensional geometric model is used as a quantitative indicator.

[0117] Table 2 gives Figure 5-7 The RMSE between the imaging results and the model is shown in Table 3. In addition, the embodiment of the present invention also conducted experiments under different signal-to-noise ratios (20, 15 and 10 dB) and different squint angles (30°, 45° and 60°), and conducted an additional repeated experiment for each. The RMSE between the imaging results and the model is also recorded in Table 3.

[0118] Table 2 RMSE between the 3D imaging results and the model at different squint angles and SNRs in the first group of experiments

[0119]

[0120]

[0121] Table 3 RMSE between 3D imaging results and models at different squint angles and SNRs in repeated experiments

[0122]

[0123] comprehensive Figure 5-7 It can be concluded from the data in Tables 2 and 3 that the method of the present invention exhibits superior imaging performance at different squint angles and different signal-to-noise ratios. At the same time, the method of the present invention is less affected by noise and has strong robustness.

[0124] In summary, the improvements of the method of the present invention are:

[0125] 1. The method of the present invention innovatively proposes a method for constructing a dynamic virtual antenna. By constructing a dynamic virtual antenna, the imaging angle of the antenna system is converted, the residual squint time-varying path difference is visualized and targeted compensation is performed.

[0126] 2. The method of the present invention innovatively applies the Harris Hawk HHO algorithm to the field of radar imaging. The algorithm uses the entropy of two-dimensional ISAR images and the entropy of synthetic images as criteria to achieve the estimation of translational motion compensation and image registration parameters, and finally achieves high-resolution ISAR imaging and ISAR image registration of the target. Based on the registered ISAR images, the present invention finally achieves InISAR three-dimensional imaging in a squint scene.

[0127] The method provided in the embodiment of the present invention can be applied to an electronic device. Specifically, the electronic device can be: a desktop computer, a portable computer, an intelligent mobile terminal, a server, etc., which is not limited in the embodiment of the present invention.

[0128] Based on the same inventive concept, an embodiment of the present invention further provides a three-dimensional imaging device of an interferometric inverse synthetic aperture radar in a squint scene. Figure 8 The present invention provides a schematic diagram of the structure of a three-dimensional imaging device of an interferometric inverse synthetic aperture radar in a squint scene. Figure 8 As shown, it includes: a pulse compression unit 801, a parameter estimation unit 802, a virtual construction unit 803, a compensation unit 804 and an image generation unit 805;

[0129] The pulse compression unit 801 is used to: perform pulse compression processing on the echo signals obtained by the right-angle L-configuration three-antenna system respectively to obtain pulse compression echo data;

[0130] The parameter estimation unit 802 is used to: perform fast Fourier transform processing on the pulse compression echo data, and perform translation motion parameter estimation based on the result of the fast Fourier transform processing and the Harris Hawk Optimization HHO algorithm to obtain the motion parameters of the target;

[0131] The virtual construction unit 803 is used to: construct a dynamic virtual antenna according to the target's motion parameters, pulse compression echo data, distance prior information, and angle prior information;

[0132] The compensation unit 804 is used to: perform squint compensation on the pulse compression echo data by calculating the dynamic baseline length and the time-varying squint path difference of the dynamic virtual antenna, and obtain the compensated echo data of each antenna in the right-angle L-configuration three-antenna system; perform translational motion compensation on the compensated echo data using the motion parameters of the target, and obtain the high-resolution ISAR image of each antenna about the target;

[0133] The image generation unit 805 is used to obtain the three-dimensional imaging result of the interferometric inverse synthetic aperture radar in the squint scene based on the high-resolution ISAR image.

[0134] Fig. 9 A schematic diagram of the structure of a three-dimensional imaging device of an interferometric inverse synthetic aperture radar in a squint scene provided by an embodiment of the present invention includes: a processor 910, a storage medium 920 and a bus 930, wherein the storage medium 920 stores machine-readable instructions executable by the processor 910, and when the three-dimensional imaging device of the interferometric inverse synthetic aperture radar in a squint scene is running, the processor 910 communicates with the storage medium 920 through the bus 930, and the processor 910 executes the machine-readable instructions to execute the steps of the above method embodiment. The specific implementation method and technical effect are similar and will not be repeated here.

[0135] The storage medium may include a random access memory (RAM) or a non-volatile memory (NVM), such as at least one disk storage. Optionally, the storage medium may also be at least one storage device located away from the aforementioned processor.

[0136] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0137] It should be noted that the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention.

[0138] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features 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 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 the different embodiments or examples described in this specification.

[0139] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art can understand and implement other changes of the above disclosed embodiments by viewing the drawings and the disclosed content. In the description of the present invention, the term "comprising" does not exclude other components or steps, "one" or "an" does not exclude multiple situations, and the meaning of "multiple" is two or more, unless otherwise clearly and specifically limited. In addition, certain measures are recorded in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0140] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A three-dimensional imaging method of interferometric inverse synthetic aperture radar in a squint scene, applied to a right-angle L-configuration three-antenna system, characterized in that: include: Performing pulse compression processing on the echo signals acquired by the right-angle L-configuration three-antenna system to obtain pulse compression echo data; The pulse compression echo data is subjected to fast Fourier transform processing, and translational motion parameters are estimated based on the result of the fast Fourier transform processing and the Harris Hawk optimized HHO algorithm to obtain the motion parameters of the target; Constructing a dynamic virtual antenna according to the motion parameters of the target, the pulse compression echo data, the distance prior information and the angle prior information; By calculating the dynamic baseline length and the time-varying squint path difference of the dynamic virtual antenna, squint compensation is performed on the pulse compression echo data to obtain the compensated echo data of each antenna in the right-angle L-configuration three-antenna system; Using the motion parameters of the target to perform translational motion compensation on the compensated echo data, so as to obtain a high-resolution ISAR image of the target from each antenna; Based on the high-resolution ISAR image, a three-dimensional imaging result of interferometric inverse synthetic aperture radar in a squint scene is obtained.

2. The three-dimensional imaging method of interferometric inverse synthetic aperture radar in a squint scene according to claim 1, characterized in that: The right-angle L-configuration three-antenna system includes: a first antenna, a second antenna, and a third antenna; The first antenna is a transceiver integrated antenna, the second antenna and the third antenna are both receiving antennas, and the first antenna is the coordinate origin of the right-angle L-configuration three-antenna system.

3. The three-dimensional imaging method of interferometric inverse synthetic aperture radar in a squint scene according to claim 2, characterized in that: The pulse compression echo data is subjected to fast Fourier transform processing, and translational motion parameter estimation is performed based on the result of the fast Fourier transform processing and the Harris Hawk optimized HHO algorithm to obtain the motion parameters of the target, including: Performing fast Fourier transform processing on the pulse compression echo data of the first antenna to obtain first echo transform data; Perform polynomial modeling on the target's motion process to obtain the target scene model; Under the target scene model, based on the first echo transform data and the HHO algorithm, translation motion parameters of the target are estimated to obtain motion parameters of the target.

4. The three-dimensional imaging method of interferometric inverse synthetic aperture radar in a squint scene according to claim 2, characterized in that: The dynamic baseline length of the dynamic virtual antenna is expressed as: L X represents the dynamic baseline length, L1 represents the distance between the first antenna and the second antenna, θ X represents the angle between the target and the x-axis at the initial moment, R(t m ) represents the slow time moment t m The distance between the rotation center of the target and the first antenna when the target moves, wherein the dynamic baseline length represents the distance between the first antenna and the dynamic virtual antenna during the target movement; The time-varying slant path difference of the dynamic virtual antenna is expressed as: BB″ represents a time-varying squint path difference, wherein the time-varying squint path difference represents the distance between the second antenna and the dynamic virtual antenna.

5. The three-dimensional imaging method of interferometric inverse synthetic aperture radar in a squint scene according to claim 2, characterized in that: The method of calculating the dynamic baseline length and the time-varying squint path difference of the dynamic virtual antenna, performing squint compensation on the pulse compression echo data, and obtaining the compensated echo data of each antenna in the right-angle L-configuration three-antenna system, includes: Convolution processing is performed on the phase corresponding to the time-varying squint path difference and the pulse compression echo data of the second antenna and the third antenna respectively, so as to obtain the second compensation echo data and the third compensation echo data after squint compensation; The pulse compression echo data of the first antenna, the second compensation echo data and the third compensation echo data together constitute the compensation echo data of the right-angle L-configuration three-antenna system.

6. The three-dimensional imaging method of interferometric inverse synthetic aperture radar in a squint scene according to claim 1, characterized in that: The method of obtaining a three-dimensional imaging result of an interferometric inverse synthetic aperture radar in a squint scene based on the high-resolution ISAR image includes: The high-resolution ISAR images of all antennas are modulo-added to obtain a composite image; Performing image registration on the high-resolution ISAR image according to the entropy of the synthetic image to obtain a high-resolution ISAR registered image; The high-resolution ISAR registration image is subjected to interference processing to obtain the three-dimensional imaging result.

7. The three-dimensional imaging method of interferometric inverse synthetic aperture radar in a squint scene according to claim 6, characterized in that: The performing image registration on the high-resolution ISAR image according to the entropy of the synthetic image to obtain a high-resolution ISAR registered image includes: Performing image registration on the high-resolution ISAR image using the HHO algorithm and the synthetic image; When the change in entropy of the synthetic image is less than a preset threshold, the high-resolution ISAR registration image is obtained accordingly.

8. A three-dimensional imaging device for interferometric inverse synthetic aperture radar in a squint scene, applied to a right-angle L-configuration three-antenna system, characterized in that: It includes: a pulse compression unit, a parameter estimation unit, a virtual construction unit, a compensation unit and an image generation unit; The pulse compression unit is used to: perform pulse compression processing on the echo signals obtained by the right-angle L-configuration three-antenna system respectively to obtain pulse compression echo data; The parameter estimation unit is used to: perform fast Fourier transform processing on the pulse compression echo data, perform translation motion parameter estimation based on the result of the fast Fourier transform processing and the Harris Hawk Optimization HHO algorithm, and obtain the motion parameters of the target; The virtual construction unit is used to: construct a dynamic virtual antenna according to the motion parameters of the target, the pulse compression echo data, the distance prior information and the angle prior information; The compensation unit is used to: perform squint compensation on the pulse compression echo data by calculating the dynamic baseline length and the time-varying squint path difference of the dynamic virtual antenna to obtain the compensated echo data of each antenna in the right-angle L-configuration three-antenna system; perform translational motion compensation on the compensated echo data using the motion parameters of the target to obtain a high-resolution ISAR image of each antenna about the target; The image generation unit is used to obtain a three-dimensional imaging result of an interferometric inverse synthetic aperture radar in a squint scene based on the high-resolution ISAR image.

9. A three-dimensional imaging device for interferometric inverse synthetic aperture radar in a squint scene, characterized in that: include: A processor, a storage medium and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, and when the three-dimensional imaging device of the interferometric inverse synthetic aperture radar in the squint scene is running, the processor communicates with the storage medium through the bus, and the processor executes the machine-readable instructions to perform the steps of the three-dimensional imaging method of the interferometric inverse synthetic aperture radar in the squint scene as described in any one of claims 1 to 7.

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