Frequency spectrum reconstruction method and device for high-speed platform oblique side array multichannel SAR signals under diving track

Abstract

The invention discloses a frequency spectrum reconstruction method and device for a high-speed platform oblique side array multichannel SAR signal under a diving track. Comprising the following steps: acquiring multi-channel echo signals; performing coordinate rotation transformation processing and distance pulse compression on the multi-channel echo signal to obtain a pulse pressure signal; sequentially carrying out distance FFT (Fast Fourier Transform), linear walking correction, azimuth FFT and distance IFFT on the pulse pressure signal of each channel to obtain a processed signal of each channel; performing distance partitioning on the processed signal of each channel; determining a spatial domain filtering weight vector by adopting a steering vector matrix, wherein an expression of the steering vector matrix is obtained by modeling a space-time spectrum of the oblique side array multi-channel SAR under the diving trajectory; and according to the spatial filtering weight vector, Doppler spectrum reconstruction is carried out on the echo signal after distance partitioning, and an equivalent single-channel two-dimensional unambiguous echo signal is obtained. According to the method, the accurate spectrum reconstruction of the high-speed platform oblique side array multichannel SAR signal under the diving track can be realized.

Description

Technical Field

[0001] This invention belongs to the field of radar technology, specifically relating to a method and device for spectrum reconstruction of multi-channel SAR signals from a high-speed platform under a dive trajectory. Background Technology

[0002] With the significant increase in platform flight speed, single antennas are limited by the minimum antenna area required for unambiguous imaging in Synthetic Aperture Radar (SAR) systems. It is difficult to simultaneously achieve unambiguous range and azimuth imaging. Multi-channel SAR systems can overcome these limitations, enabling unambiguous SAR imaging at high speeds. Conventional multi-channel SAR systems typically deploy their channel arrays linearly along the horizontal direction. However, for SAR platforms with complex shapes and limited internal space, horizontally deployed multi-channel systems cannot be accommodated. Oblique-array multi-channel systems, on the other hand, have an array axis at an angle to the horizontal direction. By flexibly adjusting the installation angle, they can fully utilize the platform's internal space, making them more adaptable to SAR platforms with limited internal space.

[0003] For subsequent imaging processing, spectral reconstruction of oblique-array multi-channel SAR signals is crucial. However, in a dive trajectory, the radar platform has a three-dimensional flight velocity, and current multi-channel SAR spectral reconstruction methods are designed based on level flight trajectory models, which cannot be applied to the spectral reconstruction of oblique-array multi-channel SAR signals in a dive trajectory. Therefore, there is an urgent need for a spectral reconstruction method for oblique-array multi-channel SAR signals of high-speed platforms in a dive trajectory. Summary of the Invention To address the aforementioned problems in the prior art, this invention provides a method and device for spectrum reconstruction of multi-channel SAR signals from a high-speed platform under a dive trajectory.

[0004] The technical problem to be solved by this invention is achieved through the following technical solution: This invention provides a method for spectral reconstruction of multi-channel SAR signals from a high-speed platform under a dive trajectory, comprising: Acquire multi-channel echo signals, wherein the multi-channel echo signals are azimuth-ambiguous multi-channel data; The multi-channel echo signal is sequentially subjected to coordinate rotation transformation and distance pulse compression to obtain the pulse-compressed multi-channel echo signal. The pulse-compressed echo signal of each channel is sequentially processed by range FFT, linear motion correction, azimuth FFT and range IFFT to obtain the range-time-domain and azimuth-frequency-domain echo signal of each channel after motion correction. The distance-time-domain, azimuth-frequency-domain echo signals after motion correction processing for each channel are all divided into distance blocks; The spatial filtering weight vectors of each Doppler ambiguity direction of the Doppler cell are determined by using a steering vector matrix, wherein the expression of the steering vector matrix is ​​obtained by modeling the spatiotemporal spectrum of a downslope multichannel SAR with a dive trajectory. Based on the spatial filtering weight vectors of each Doppler ambiguity direction, the echo signal after range segmentation is reconstructed using the Doppler spectrum to obtain an equivalent single-channel two-dimensional unambiguous echo signal.

[0005] The present invention also provides a spectrum reconstruction device for multi-channel SAR signals of a high-speed platform under a dive trajectory, comprising a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; The memory is used to store computer programs; When the processor executes the program stored in the memory, it implements the steps of the above-mentioned method for spectral reconstruction of multi-channel SAR signals of a high-speed platform under a dive trajectory.

[0006] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention accurately models the spatiotemporal spectrum of a multi-channel SAR array with an oblique array under a dive trajectory, deriving an analytical expression for the nonlinear steering vector and analyzing its range non-stationary characteristics. Based on this, the multi-channel echo signal is divided into range blocks, and spectral reconstruction is performed using spatial filtering methods to obtain an equivalent single-channel unambiguous echo signal. This lays the foundation for subsequent unambiguous SAR imaging and achieves accurate spectral reconstruction of high-speed platform oblique array multi-channel SAR signals under a dive trajectory. This invention effectively overcomes the range non-stationarity problem of oblique array multi-channel SAR signals through range block spectral reconstruction processing, and can simultaneously achieve accurate spectral reconstruction of targets at different distances in the scene. This invention is applicable to the spectral reconstruction of conventional multi-channel arrays deployed horizontally and oblique array multi-channel arrays under horizontal or dive trajectories, effectively improving the algorithm's adaptability to radar platforms and flight trajectories.

[0007] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0008] Figure 1 This is a schematic flowchart of a method for spectral reconstruction of a multi-channel SAR signal from a high-speed platform under a dive trajectory, provided by an embodiment of the present invention. Figure 2 This is another flowchart illustrating a method for spectral reconstruction of multi-channel SAR signals from a high-speed platform under a dive trajectory, provided in an embodiment of the present invention. Figure 3This is a schematic diagram of the array configuration of a slanted array multichannel SAR; Figure 4 This is a top view schematic diagram of the rotation transformation process provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the geometric model of oblique side array multi-channel SAR imaging; Figure 6 This is a schematic diagram illustrating the derivation of the guiding vector provided in an embodiment of the present invention; Figure 7a This is a schematic diagram of the result of spectrum reconstruction of the echo signal using conventional spatial filtering methods; Figure 7b This is a schematic diagram showing the result of spectrum reconstruction of the echo signal using the method proposed in this invention; Figure 8a This is another schematic diagram showing the result of spectrum reconstruction of the echo signal using conventional spatial filtering methods; Figure 8b This is another schematic diagram showing the result of spectrum reconstruction of the echo signal using the method proposed in this invention; Figure 9 This is a schematic diagram of the imaging result obtained by using the BP algorithm to image the spectral reconstruction result of the method proposed in this invention. Figures 10a-10c This is a schematic diagram illustrating the imaging results analysis of a point target in the upper left corner of the scene; Figures 11a-11c This is a schematic diagram illustrating the imaging results analysis of a point target at the center of the scene; Figures 12a-12c This is a schematic diagram illustrating the imaging results analysis of a point target in the lower right corner of the scene. Detailed Implementation

[0009] 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.

[0010] Figure 1 This is a schematic flowchart of a method for spectral reconstruction of a multi-channel SAR signal from a high-speed platform under a dive trajectory, provided by an embodiment of the present invention. Figure 2 This is a schematic flowchart illustrating a method for spectral reconstruction of multi-channel SAR signals from a high-speed platform under a dive trajectory, provided by an embodiment of the present invention. (Combined with...) Figure 1 and Figure 2 It can be seen that the method includes: S101. Acquire multi-channel echo signals. Multi-channel echo signals are azimuth-ambiguous multi-channel data.

[0011] For example, a multi-channel echo signal can be M Azimuth ambiguity echo data for each channel.

[0012] S102. Perform coordinate rotation transformation and distance pulse compression on the multi-channel echo signal in sequence to obtain the pulse-compressed multi-channel echo signal.

[0013] S103. Perform range FFT transformation, linear motion correction processing, azimuth FFT transformation and range IFFT transformation processing on the pulse-compressed echo signal of each channel in sequence to obtain the range, time domain and azimuth frequency domain echo signal after motion correction processing for each channel.

[0014] Specifically, such as Figure 2 As shown, for the echo signal of each channel, a range FFT transform is first performed, and then a linear travel correction function is used to perform linear travel correction on the echo signal after the range FFT transform. After that, the azimuth FFT transform and range IFFT transform are performed on the echo signal after linear travel correction in sequence to obtain the range, time domain, azimuth, and frequency domain echo signal after travel correction processing for that channel.

[0015] S104. The distance, time-domain, azimuth, and frequency-domain echo signals after the movement correction processing of each channel are all divided into distance blocks.

[0016] S105. The spatial filtering weight vector of each Doppler ambiguity direction of the Doppler cell is determined by using the steering vector matrix. The expression of the steering vector matrix is ​​obtained by modeling the spatiotemporal spectrum of the downslope array multichannel SAR of the dive trajectory.

[0017] S106. Based on the spatial filtering weight vectors of each Doppler ambiguity direction, the echo signal after distance segmentation is reconstructed using the Doppler spectrum to obtain an equivalent single-channel two-dimensional unambiguous echo signal.

[0018] Here, precise spatiotemporal spectral modeling can be performed in advance to obtain the steering vector matrix, and then the spatial filtering weight vector can be determined. After that, the range-time-azimuth-frequency echo signals after travel correction processing for each channel are divided into range blocks. Finally, the Doppler spectrum reconstruction of the range-blocked echo signals is performed using the spatial filtering weight vector. Alternatively, the range-time-azimuth-frequency echo signals after travel correction processing for each channel can be divided into range blocks first, and then precise spatiotemporal spectral modeling can be performed to obtain the steering vector matrix. Then, the spatial filtering weight vector can be determined, and finally, the Doppler spectrum reconstruction of the range-blocked echo signals is performed using the spatial filtering weight vector.

[0019] It should be noted that after range correction processing of the range-time-azimuth-frequency-domain echo signals for each channel, range blocks are applied to ensure that each range block contains a portion of the echo signals from all channels. Therefore, it can be calculated according to... Figure 2As shown, Doppler spectrum reconstruction is performed on a portion of the echo signals of all channels in each range block in sequence until all range blocks have been traversed. Based on the Doppler spectrum reconstruction results of a portion of the echo signals of all range blocks, an equivalent single-channel two-dimensional unambiguous echo signal is obtained.

[0020] It should be noted that, as Figure 2 As shown, the final equivalent single-channel two-dimensional unambiguous echo signal can be used for unambiguous SAR imaging to obtain unambiguous SAR images.

[0021] In some embodiments, the above-mentioned S102 is implemented through the following steps: S1021, Based on the radar platform's flight speed vector Velocity vector after projection onto the ground In the imaging coordinate system of Axis and Components of the axis and Calculate the rotation angle .

[0022] Specifically, , express In the imaging coordinate system of Components of the axis, express In the imaging coordinate system of Components of the axis, This represents the inverse cosine function.

[0023] S1022, Based on the velocity vector in the imaging coordinate system of The sign of the axis components will affect the imaging coordinate system. Axis and Axis winding All axes rotate ,get Axis and axis, and the imaging coordinate system of Axis as Axis, obtained from axis, axis, Axis and imaging coordinate system The origin The rotated coordinate system .

[0024] S1023, Transfer the multi-channel echo signal from the imaging coordinate system Transform to the rotated coordinate system In the process, the multi-channel echo signal after rotation transformation is obtained.

[0025] Here, we first introduce the array configuration of oblique-array multi-channel SAR. For a multi-channel SAR system operating in single-transmit / multi-receive mode, after equivalent phase center processing, we can assume that each channel transmits and receives automatically at the equivalent phase center location. We assume there are a total of... There are 1 channel (taking an odd number as an example), and each channel is numbered as follows: After equivalent phase center processing, the channel To the central passage The spacing is (in the central passage) Ahead, (positive for positive, negative for negative), representing the unit vector along the channel axis as... , , In the imaging coordinate system of , and The three components on the axis. Taking a three-channel system as an example, the array configuration diagram of a slanted array multi-channel SAR is shown below. Figure 3 As shown, the imaging coordinate system of , and These are the distance axis, azimuth axis, and altitude axis, respectively. For example... Figure 3 As shown, the channels are distributed in a plane. Inside, assuming a plane Pitch angle (relative to plane) The included angle is Then the installation angle between the channel array axis and the horizontal direction is . The projection of each passage onto the ground is .

[0026] To reduce the complexity of subsequent spectral reconstruction, the imaging coordinate system is first... A rotational transformation is performed to make the range velocity of the radar platform (i.e., the multi-channel SAR system) zero. Assume the radar platform's flight velocity vector is... ,but The velocity vector projected onto the ground plane is First, calculate the vector. In the initial coordinate system Angle between axes : Then, fix the origin. , Initial coordinate plane about the height axis Rotation angle Then the rotated coordinate system can be obtained. A top view of the rotation transformation process is shown below. Figure 4 As shown. It should be noted that when When it is negative, the imaging coordinate system of Axis and Axis winding The shafts rotate counterclockwise. , and when When positive, the imaging coordinate system of Axis and Axis winding The shafts rotate clockwise. After the coordinate system rotation, the radar platform's flight velocity vector... Transform into ,in: The channel axis vector is ,in: .

[0027] S1024. Perform distance pulse compression processing on the multi-channel echo signal after rotation transformation to obtain the pulse-compressed multi-channel echo signal.

[0028] Here, the geometric model of oblique side array multi-channel SAR imaging is as follows: Figure 5 As shown. The echo signal model for a slanted array multi-channel SAR is derived below. Assume the radar platform moves along... Figure 5 The blue trajectory in the image indicates that the geometric center of the radar platform is located at point [location missing] at the azimuth center. Flight altitude is Its ground projection is the origin. Assume the center of the scene is a point. Its ground yaw angle is ,point Time The slope distance is The projected length of this slant distance on the ground plane is Then point The coordinates can be represented as Assume there is an arbitrary point target in the scene. Its yaw angle is .point Time The slope distance is Its ground projection is Then point The coordinates can be represented as .aisle At any position The position is Then the channel Time instantaneous slant distance for: The radar transmits a linear frequency modulated signal. Assuming the echo signal is unambiguous in both the range and azimuth directions, after pulse compression, the channel... The received echo signal is represented as: ,in, Indicates distance over time. Point The scattering intensity, Indicates the transmission bandwidth. Represents the speed of light. Indicates the signal wavelength.

[0029] Before performing spectrum reconstruction, the pulse-compressed echo signal needs to undergo linear motion correction processing to compensate for the Doppler center of the echo and correct the two-dimensional coupling of the spectrum, thereby reducing the Doppler bandwidth. Specifically, from the point... Point to the center of the scene The vector is , The pitch angle is Then the echo Doppler at the center of the scene at the azimuth center time is: The expression for the linear movement correction function is: ,in, Indicates distance frequency, This indicates the carrier frequency of the signal. Then the channel can be... Received echo signal pairs Perform a Fourier transform, then multiply it in the range frequency domain by the linear traverse correction function, and then... and Perform a Fourier transform to obtain the channel. The distance-time-domain and azimuth-frequency-domain echo signals after movement correction processing ,in, Indicates the baseband azimuth frequency. is the pulse repetition frequency.

[0030] In some embodiments, S104 specifically involves: dividing the range-time-domain, azimuth-frequency-domain echo signal after the travel correction processing of each channel into... Each distance block is used to obtain the echo signal of each distance block in each channel.

[0031] For a azimuth multichannel SAR system, each Doppler cell corresponds to One direction of arrival, therefore, from The steering vectors of the Doppler blur direction are combined to form a steering vector matrix. For example, the steering vector matrix... The expression is: ,in, Indicates matrix transpose. Represents Doppler units The The steering vector of the Doppler blur direction, Represents Doppler units The steering vector of the 0th Doppler blur direction, Represents Doppler units The A steering vector for the direction of Doppler blur.

[0032] The following explains the process of obtaining the steering vector matrix by modeling the spatiotemporal spectrum of a downsloping side array multichannel SAR on a dive trajectory: For a multi-channel azimuth SAR system, the echo signal received by each channel is a superposition of multiple Doppler ambiguity components, with the Doppler ambiguity factor being... ,in, Let be the Doppler bandwidth in the unambiguous case. The following assumes the Doppler ambiguity factor is . (Taking odd numbers as an example), where, If the integer is positive, then the index value of the Doppler blur component is... Then the channel The received azimuth ambiguity signal is represented as: In radar array signal processing, spatial steering vectors can be constructed based on the echo phase difference caused by the spatial position differences of each channel. : This vector characterizes the structure of the signal's spatiotemporal spectrum and is crucial for spectral reconstruction in multi-channel SAR systems. The following section combines... Figure 6 The relationship between the phase difference of the echo from a multi-channel SAR with a downslope array and the echo Doppler effect is analyzed, and its spatiotemporal spectrum model is derived. For example... Figure 6 As shown, for any point in the scene From point Point of view The vector is Channel axis vector and Form a plane The normal vector perpendicular to the plane and pointing upwards. It can be represented as: Calculate the channel axis vector With plane normal vector The outer product of the outer product yields the channel array in the plane. The normal vector pointing inwards towards the target side: Then the channel array normal vector modulus The expression is: Then the channel array normal vector and vector The included angle The expression is: From the above The expression can be deduced by analogy, at the azimuth center time point The echo Doppler is: ,in For vectors The pitch angle. Therefore, point The ground yaw angle can be expressed using echo Doppler as: Substitute this expression into the above The expression can be used to obtain The included angle is indicated The expression: . This Substituting the expression into the above... From the expression, we can obtain the effect of multi-channel SAR with oblique side array on fuzzy components in the dive trajectory. The guide vector : For azimuth multichannel SAR, each Doppler cell corresponds to... One destination direction, from By combining the steering vectors of the Doppler blur direction, the steering vector matrix can be obtained. : .

[0033] It should be noted that, according to the above The spatiotemporal spectrum of the oblique array multichannel SAR under the dive trajectory was characterized, based on The expression shows that the spatiotemporal spectrum is related to the slant range variable of the target. , and pitch angle Relatedly, the spatiotemporal spectra corresponding to different range units do not coincide in the spatiotemporal plane. Especially in the short range, the spatiotemporal characteristics of the signal change more drastically. Therefore, this invention divides the echo signal into blocks in the range direction and constructs a steering vector matrix based on the slant range and pitch angle parameters corresponding to the center of each range block. Subsequently, the spectrum of each range block signal is reconstructed one by one. In this way, the influence of range non-stationary characteristics can be overcome, thereby improving the reconstruction accuracy.

[0034] In this invention, after obtaining the guiding vector matrix Then, according to Determine the doppler unit of Spatial filtering weight vectors for the Doppler blur direction are used to zero out the blurred spectral components, thereby recovering the unblurred signal. For example, for a certain Doppler unit... To reconstruct its first A fuzzy component Then the spatial filtering weight vector needs to be set to the first... The output for the first Doppler blur direction is 1, and the output for the other blur directions is 0. Therefore, the output for the first Doppler blur direction is 1. The spatial filtering weight vectors for each Doppler blur direction are: , It is an integer. The value is , Represents a matrix Seeking pseudo-reversal, ,and, elements in , All other elements in the array are zero.

[0035] In some embodiments, the above-mentioned S106 is implemented through the following steps: S1061. Extract the echo signals of all channels for each distance block.

[0036] Specifically, for each range block, the echo signals of all channels within that range block are extracted and arranged into a vector form, thus obtaining the echo signals of all channels within that range block. For example, the first... Echo signals from all channels of each distance block The expression is: ,in, Indicates the first channel's... The echo signal of each distance block, Indicates the second channel's... The echo signal of each distance block, Similarly, is a positive integer, The value is .

[0037] S1062. Using the spatial filtering weight vector of each Doppler ambiguity direction, extract the corresponding Doppler unambiguous component from the echo signals of all channels of each range block.

[0038] For example, using the first Spatial filtering weight vectors in the direction of Doppler blur From the first Echo signals from all channels of each distance block Extracting a Doppler unambiguous component The expression is: ,in, Indicates distance over time. Represents Doppler units The One ambiguous component. Following this procedure, the echo signal can be... Extract the unambiguous Doppler components one by one from the data, thereby obtaining the unambiguous components from the data. Extract One Doppler unambiguous component, that is, All Doppler unambiguous components.

[0039] S1063. Based on all Doppler unambiguous components of the echo signals of all channels of each range block, reconstruct the Doppler unambiguous signal of each range block.

[0040] For example, in obtaining of After the Doppler unambiguous components, this can be... By arranging the unambiguous Doppler components in order, we can obtain the first... Doppler unambiguous signal from each distance block ,and, The expression is: .

[0041] S1064, according to The Doppler unambiguous signal of each distance block is used to obtain the equivalent single-channel two-dimensional unambiguous echo signal.

[0042] In some embodiments, for The echo signals from all channels of each distance block are sequentially subjected to the above spatial filtering process, and the reconstructed signals are then processed. By arranging the Doppler unambiguous signals of each distance block in distance order, the final equivalent single-channel two-dimensional unambiguous echo signal can be obtained. ,and, The expression is: .

[0043] This invention also provides a spectrum reconstruction device for multi-channel SAR signals of a high-speed platform under a dive trajectory, comprising a processor, a communication interface, a memory, and a communication bus. The processor, communication interface, and memory communicate with each other through the communication bus. The memory is used to store computer programs. The processor is used to execute the program stored in the memory to implement the steps of the spectrum reconstruction method for multi-channel SAR signals of a high-speed platform under a dive trajectory.

[0044] The effectiveness of the signal spectrum reconstruction method proposed in this invention will be verified through simulation experiments below.

[0045] 1) Simulation conditions Table 1

[0046] Will Set to 43° Set to 30°, set 3 distributed channels, and set the coordinates of each channel as (0.033m, -0.083m, -0.035m), (0m, 0m, 0m), and (-0.033m, 0.083m, 0.035m).

[0047] 2) Simulation content and result analysis A point target was placed at an angle of 30° and a slant distance of 110km. The echo signal exhibited 3x Doppler ambiguity. Conventional spatial filtering methods were used to reconstruct the spectrum of the echo signal, and the results are as follows: Figure 7a As shown, energy leakage exists in the reconstructed signal spectrum, and the ambiguity components are not completely suppressed, which will reduce the focusing quality of subsequent SAR imaging. The reconstruction result using the method proposed in this invention is as follows: Figure 7b As shown, the reconstructed signal spectrum does not exhibit energy leakage, and the ambiguity components are effectively suppressed.

[0048] Nine × nine point targets were set at an angle of 30° and an angle of 110km, with a scene width of 5.7km (range) × 3.5km (azimuth). The echo signal exhibited 3x Doppler blur. Conventional spatial filtering methods were used to reconstruct the Doppler echo signal, and the results are as follows. Figure 8a As shown, Doppler blurring still exists in the azimuth direction. The spectral reconstruction result using the method proposed in this invention is as follows: Figure 8b As shown, the fuzzy components are effectively suppressed.

[0049] The spectral reconstruction results of the proposed method were imaged using the BP algorithm, and the imaging results are as follows: Figure 9 As shown, the imaging results are clear and free of blur. Figure 9 Select a point target (i.e., ...) at the top left corner, center, and bottom right corner of the scene shown. Figure 9 The three points circled in red are analyzed using their contour maps and 2D profiles to obtain the target point in the upper left corner of the scene. Figures 10a-10c The point target at the center of the scene Figures 11a-11c The target point in the bottom right corner of the scene Figures 12a-12c ,in, Figure 10a , Figure 11a and Figure 12a It is a contour map. Figure 10b , Figure 11b and Figure 12b It is a distance profile. Figure 10c , Figure 11c and Figure 12c This is an azimuth profile. It is evident that the focusing effect on point targets at different distances is excellent, demonstrating the effectiveness of the proposed oblique-array multi-channel SAR signal spectrum reconstruction method.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions 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 suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0051] In this specification, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. While different embodiments may describe certain measures, this does not mean that these measures cannot be combined to produce a good effect.

[0052] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for spectral reconstruction of multi-channel SAR signals from a high-speed platform with a slanted array under a dive trajectory, characterized in that, include: Acquire multi-channel echo signals, wherein the multi-channel echo signals are azimuth-ambiguous multi-channel data; The multi-channel echo signal is sequentially subjected to coordinate rotation transformation and distance pulse compression to obtain the pulse-compressed multi-channel echo signal. The pulse-compressed echo signal of each channel is sequentially processed by range FFT, linear motion correction, azimuth FFT and range IFFT to obtain the range-time-domain and azimuth-frequency-domain echo signal of each channel after motion correction. The distance-time-domain, azimuth-frequency-domain echo signals after motion correction processing for each channel are all divided into distance blocks; The spatial filtering weight vectors of each Doppler ambiguity direction of the Doppler cell are determined by using a steering vector matrix, wherein the expression of the steering vector matrix is ​​obtained by modeling the spatiotemporal spectrum of a downslope multichannel SAR with a dive trajectory. Based on the spatial filtering weight vectors of each Doppler ambiguity direction, the echo signal after range segmentation is reconstructed using the Doppler spectrum to obtain an equivalent single-channel two-dimensional unambiguous echo signal.

2. The spectral reconstruction method for multi-channel SAR signals of a high-speed platform under a dive trajectory as described in claim 1, characterized in that, The process of sequentially performing coordinate rotation transformation and distance pulse compression on the multi-channel echo signal to obtain the pulse-compressed multi-channel echo signal includes: Based on the velocity vector of the radar platform's flight velocity vector projected onto the ground in the imaging coordinate system of Axis and Calculate the rotation angle of the axis components ; According to the velocity vector in the imaging coordinate system of The sign of the axis components determines the orientation of the imaging coordinate system. Axis and Axis winding All axes rotate ,get Axis and axis, and the imaging coordinate system of Axis as Axis, obtained from axis, axis, Axis and the imaging coordinate system The origin The rotated coordinate system ; The multi-channel echo signal is transferred from the imaging coordinate system Transform to the rotated coordinate system In the process, the multi-channel echo signal after rotation transformation is obtained; The multi-channel echo signal after rotation transformation is subjected to distance pulse compression processing to obtain the pulse-compressed multi-channel echo signal.

3. The spectral reconstruction method for multi-channel SAR signals of a high-speed platform under a dive trajectory according to claim 2, characterized in that, The rotation angle The expression is as follows: ； in, The velocity vector is represented in the imaging coordinate system. of Components of the axis, The velocity vector is represented in the imaging coordinate system. of Components of the axis, This represents the inverse cosine function.

4. The spectral reconstruction method for multi-channel SAR signals of a high-speed platform under a dive trajectory according to claim 2, characterized in that, When the velocity vector is in the imaging coordinate system of When the axis component is negative, the imaging coordinate system is... of Axis and Axis winding The shafts rotate counterclockwise. When the velocity vector is in the imaging coordinate system of When the components of the axis are positive, the imaging coordinate system is... of Axis and Axis winding The shafts rotate clockwise. .

5. The spectral reconstruction method for multi-channel SAR signals of a high-speed platform under a dive trajectory according to claim 1, characterized in that, The range-time-domain, azimuth-frequency-domain echo signals after travel correction processing for each channel are all divided into range blocks, including: The distance, time, azimuth, and frequency domain echo signals after travel correction for each channel are divided into... Each distance block is used to obtain the echo signal of each distance block in each channel.

6. The spectral reconstruction method for multi-channel SAR signals of a high-speed platform under a dive trajectory according to claim 5, characterized in that, The step of reconstructing the Doppler spectrum of the echo signal after range segmentation based on the spatial filtering weight vectors of each Doppler ambiguity direction to obtain an equivalent single-channel two-dimensional unambiguous echo signal includes: Extract the echo signals of all channels for each distance block; Using the spatial filtering weight vector for each Doppler ambiguity direction, a corresponding Doppler unambiguous component is extracted from the echo signals of all channels in each range block; Based on all Doppler unambiguous components of the echo signals from all channels of each range block, the Doppler unambiguous signal of each range block is reconstructed. according to The Doppler unambiguous signal of each distance block is used to obtain the equivalent single-channel two-dimensional unambiguous echo signal.

7. The spectral reconstruction method for multi-channel SAR signals of a high-speed platform under a dive trajectory as described in claim 6, characterized in that, Adopting the first The spatial filtering weight vector of the Doppler blur direction, from the th A Doppler unambiguous component extracted from the echo signals of all channels of a distance block. The expression is as follows: ； in, Indicates distance over time. Represents Doppler units The A fuzzy component, Indicates the first Echo signals from all channels of each distance block, Indicates the first Spatial filtering weight vectors for the Doppler blur direction. It is an integer. The value is , and All are positive integers. The value is .

8. The spectral reconstruction method for multi-channel SAR signals of a high-speed platform under a dive trajectory according to claim 7, characterized in that, The expression is as follows: ； in, Represents a matrix Seeking pseudo-reversal, Represents the guiding vector matrix. , This represents the matrix transpose, and... elements in , All other elements in the array are zero.

9. The method for spectral reconstruction of multi-channel SAR signals from a high-speed platform under a dive trajectory according to claim 1 or 8, characterized in that, The expression for the guiding vector matrix is ​​as follows: ； in, Indicates matrix transpose. Represents Doppler units The The steering vector of the Doppler blur direction, Represents Doppler units The steering vector of the 0th Doppler blur direction, Represents Doppler units The A steering vector for the direction of Doppler blur.

10. A spectrum reconstruction device for multi-channel SAR signals from a high-speed platform under a dive trajectory, comprising a processor, a communication interface, a memory, and a communication bus, characterized in that, The processor, the communication interface, and the memory communicate with each other via the communication bus; The memory is used to store computer programs; When the processor executes a program stored in the memory, it implements the steps of the method described in any one of claims 1-9.

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