Multi-channel moving target detection method based on two-dimensional difference measurement angle in clutter environment

Abstract

The application provides a SAR multi-channel moving target detection method based on two-dimensional and difference angle measurement technology in a clutter environment, and aims at the problem that the energy of a moving target cannot be accumulated due to the influence of the speed of the moving target in a multi-channel SAR radar system in a clutter environment, so that target detection cannot be realized. The method estimates the azimuth angle and the elevation angle of the moving target by using single pulse and difference angle measurement technology, and combines beam forming technology, SAR multi-channel clutter cancellation technology, constant false alarm detection technology and multi-target clustering technology to complete the detection of the moving target. The method calculates the angle discrimination curve by using a two-dimensional array directional diagram, so that the influence of interference suppression on the angle discrimination curve is avoided. Meanwhile, the method only needs one PRT pulse echo data to detect the moving target, reduces the azimuth accumulation time of the SAR system, greatly reduces the time cost in the moving target detection and improves the detection efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of moving target detection, and relates to a multi-channel moving target detection method based on two-dimensional sum and difference angle measurement in clutter environments. Background Technology

[0002] For moving targets in cluttered environments, the non-cooperative nature of the moving targets means that their radial velocity not only causes range ambiguity but also azimuth shift. Furthermore, their azimuth velocity can cause image defocusing and blurring, thus affecting target detection and subsequent imaging processing. Additionally, the radar receives clutter along with the target echo, often obscuring the target's echo and making target detection even more difficult.

[0003] To address the aforementioned problems in moving target detection, clutter suppression can be applied to the echoes to filter out clutter information and reduce its impact on the target echoes. Then, a multi-channel sum-difference angle measurement method is used to obtain the angle information of the moving target to achieve detection. However, interference suppression affects the weight vector of the sum-difference beam, causing distortion of the sum-difference beam pattern and the angle discrimination curve, leading to angle estimation errors and affecting subsequent target detection results. To improve the accuracy of angle calculation, this invention discloses a multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in cluttered environments. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-channel moving target detection method based on two-dimensional sum and difference angle measurement in cluttered environments. This method can effectively avoid the impact of interference suppression on the angle discrimination curve. At the same time, this invention only requires one PRT pulse echo data to detect moving targets, reducing the azimuth accumulation time of the SAR radar system. In moving target detection, this method can greatly reduce time costs and improve detection efficiency.

[0005] This invention is achieved through the following technical solution: A multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in cluttered environments, implemented using a multi-channel SAR radar system, includes the following steps: Step 1: Calculate the radiation pattern function of the array antenna of the multi-channel SAR radar system based on the range of azimuth and elevation angles, and calculate the azimuth difference slope and elevation difference slope based on the radiation pattern function. Step 2: Receive single pulse echoes from moving targets using a multi-channel SAR radar system, and perform range pulse compression on the single pulse echoes from moving targets; Step 3: Generate range pulse compression results and channel data, azimuth difference channel data, and elevation difference channel data based on the single pulse echoes of moving targets received by different channels in the multi-channel SAR radar system; Step 4: Receive clutter echoes through an auxiliary antenna, and suppress interference on the range pulse compression results of the clutter echoes for the sum channel data, azimuth difference channel data, and elevation difference channel data generated in Step 3. Step 5: Based on the results of Step 1 and Step 4, estimate the azimuth and pitch angles of the moving target, and perform one-dimensional CFAR detection on the estimation results. Step 6: Determine the number of moving targets. For a single moving target, directly calculate the pulse compression position of the azimuth and pitch angles of the single moving target. For multiple moving targets, use clustering to extract the pulse compression position of each moving target. Step 7: Determine the azimuth and pitch angles of the moving target based on the pulse compression position, and plot the determined azimuth and pitch angles onto a two-dimensional angle grid.

[0006] To better realize the present invention, step 4 further includes: Step 4.1: Set up at least two auxiliary antennas to form a clutter receiving space, and receive the echo of the interference signal through the auxiliary antennas; Step 4.2: Perform range-direction pulse compression on the interference signal echo; Step 4.3: Calculate the interference suppression weights based on the interference signal echo and the single pulse echo of the moving target, and use the interference suppression weights to suppress interference in the azimuth channel data, pitch difference channel data, and azimuth difference channel data.

[0007] To better realize the present invention, the calculation formula for the interference suppression weight is further as follows: ; in: Indicates the interference suppression weights; Represents the interference signal echo matrix; A single pulse echo matrix representing a moving target.

[0008] To better implement this invention, the formula for interference suppression using interference suppression weight pairs and channel data, azimuth difference channel data, and pitch difference channel data is further defined as follows: ; in: This represents the output result of interference suppression performed using interference suppression weight pairs and channel data, azimuth aberration channel data, and pitch aberration channel data. Indicates the interference suppression weights; Represents the interference signal echo matrix; A single pulse echo matrix representing a moving target.

[0009] To better realize the present invention, step 3 further includes: Step 3.1: Set up four receiving channels in the multi-channel SAR radar system to simultaneously receive single pulse echoes from moving targets through the four receiving channels; Step 3.2: Apply a phase correction function to correct the phase of the single pulse echo of the moving target received by the four receiving channels; Step 3.3: Calculate the sum channel data, azimuth difference channel data, and pitch difference channel data for the four receiving channels.

[0010] To better realize the present invention, the phase correction function is further defined as follows: ; Where: H represents the phase correction function with the data from the first received channel as the reference channel; j represents the imaginary unit; Indicates the slant range of the moving target relative to the receiving channel; This represents the slant range of the moving target relative to the first receiving channel; represents the signal carrier frequency; c represents the electromagnetic wave propagation speed.

[0011] To better realize this invention, the formula for calculating the slant range of the moving target relative to the receiving channel is further as follows: ; in: Indicates the slant range of the moving target relative to the receiving channel; () represents the three-dimensional coordinates of the m-th moving target; () represents the three-dimensional coordinates of the nth receiving channel, 1≤n≤4; Indicates the azimuth velocity of a moving target; Represents the radial velocity of a moving target; This indicates the speed of movement of the multi-channel SAR radar system.

[0012] To better implement this invention, the sum of the four receiving channels is further defined as follows: ; in: This represents the sum of data from the four receiving channels; This indicates the data received from the first channel; This indicates the data from the second receiving channel; This indicates the data received from the third channel; This indicates the data from the fourth receiving channel; Indicates distance in advance; The azimuth difference channel data of the four receiving channels are as follows: ; in: This represents the azimuth difference channel data of the four receiving channels; This indicates the data received from the first channel; This indicates the data from the second receiving channel; This indicates the data received from the third channel; This indicates the data from the fourth receiving channel; Indicates distance in advance; The pitch difference channel data of the four receiving channels are as follows: ; in: This represents the pitch difference channel data for the four receiving channels; This indicates the data received from the first channel; This indicates the data from the second receiving channel; This indicates the data received from the third channel; This indicates the data from the fourth receiving channel; Indicates distance in terms of fast time.

[0013] To better realize the present invention, an array coordinate system is further established with the transmitting antenna of the multi-channel SAR radar system as the origin, and the four receiving channels are located in the four quadrants of the array coordinate system respectively. Each receiving channel includes at least 80 array elements forming a rectangular array.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention proposes a SAR multi-channel moving target detection method based on two-dimensional sum-difference angle measurement technology in cluttered environments. Addressing the problem that moving targets in cluttered environments cannot accumulate energy due to their velocity, thus hindering target detection in multi-channel SAR radar systems, this invention utilizes single-pulse sum-difference angle measurement technology to estimate the azimuth and elevation angles of the moving target. This is combined with beamforming technology, SAR multi-channel clutter cancellation technology, constant false alarm rate (CFAR) detection technology, and multi-target clustering technology to complete the detection of the moving target. This method uses a two-dimensional array pattern to calculate the angle discrimination curve, avoiding the influence of interference suppression on the angle discrimination curve. Furthermore, this method requires only one PRT pulse echo data to detect the moving target, reducing the azimuth accumulation time of the SAR system, significantly reducing time costs and improving detection efficiency in moving target detection. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a schematic diagram of an antenna array; Figure 3 This is a schematic diagram showing the positions of adjacent array elements and moving targets; Figure 4 The radiation pattern of the antenna array after weighting; Figure 5 This is a schematic diagram of the weighting coefficients for the antenna array; Figure 6 This is the radiation pattern of the antenna array; Figure 7 This is the azimuth and difference beam pattern; Figure 8 This is the pitch and difference beam pattern; Figure 9 A schematic diagram of the signal before channel interference suppression for a single moving target; Figure 10 A schematic diagram of the signal after suppression of a single moving target and channel interference; Figure 11 A schematic diagram illustrating the theoretical detection of a single moving target; Figure 12 A schematic diagram of actual detection of a single moving target; Figure 13 A schematic diagram showing the results of two-dimensional angle calculation for the azimuth of a single moving target; Figure 14 A schematic diagram showing the calculation results of the pitch angle of a single moving target in two dimensions. Figure 15 A schematic diagram of the two-dimensional angular error in the orientation of a single moving target; Figure 16 A schematic diagram of the pitch angle error of a single moving target in two dimensions; Figure 17 A schematic diagram of the signal before interference suppression from multiple moving targets and channels; Figure 18 A schematic diagram of the signal after suppression of interference from multiple moving targets and channels; Figure 19 A schematic diagram illustrating the theoretical detection of multiple moving targets; Figure 20 A schematic diagram illustrating the actual detection of multiple moving targets; Figure 21 A schematic diagram showing the results of two-dimensional angle calculations for the orientation of multiple moving targets; Figure 22 A schematic diagram showing the calculation results of the pitch angle of multiple moving targets in two dimensions; Figure 23 A schematic diagram illustrating the two-dimensional angular error in the orientation of multiple moving targets; Figure 24 A schematic diagram of the pitch angle error of multiple moving targets in two dimensions. Detailed Implementation

[0016] The following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0017] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is intended to include the plural form as well. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0018] For ease of description, the words "up," "down," "left," and "right" appearing in this invention only indicate that they are consistent with the up, down, left, and right directions of the accompanying drawings themselves, and do not limit the structure. They are merely for the purpose of facilitating the description of this invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] Terminology Explanation: The terms "installation," "connection," "linking," and "fixing" in this invention should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction relationship between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0020] Example 1: This embodiment presents a multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in cluttered environments, implemented using a multi-channel SAR radar system, such as... Figure 1 , Figures 4-8 As shown, it includes the following steps: Step 1: Calculate the radiation pattern function of the array antenna of the multi-channel SAR radar system based on the range of azimuth and elevation angles, and calculate the azimuth difference slope and elevation difference slope based on the radiation pattern function. Step 2: Receive single pulse echoes from moving targets using a multi-channel SAR radar system, and perform range pulse compression on the single pulse echoes from moving targets; Step 3: Generate range pulse compression results and channel data, azimuth difference channel data, and elevation difference channel data based on the single pulse echoes of moving targets received by different channels in the multi-channel SAR radar system; Step 4: Receive clutter echoes through an auxiliary antenna, and suppress interference on the range pulse compression results of the clutter echoes for the sum channel data, azimuth difference channel data, and elevation difference channel data generated in Step 3. Step 5: Based on the results of Step 1 and Step 4, estimate the azimuth and pitch angles of the moving target, and perform one-dimensional CFAR detection on the estimation results. Step 6: Determine the number of moving targets. For a single moving target, directly calculate the pulse compression position of the azimuth and pitch angles of the single moving target. For multiple moving targets, use clustering to extract the pulse compression position of each moving target. Step 7: Determine the azimuth and pitch angles of the moving target based on the pulse compression position, and plot the determined azimuth and pitch angles onto a two-dimensional angle grid.

[0021] Step 3 specifically includes: Step 3.1: Set up four receiving channels in the multi-channel SAR radar system to simultaneously receive single pulse echoes from moving targets through the four receiving channels; Step 3.2: Apply a phase correction function to correct the phase of the single pulse echo of the moving target received by the four receiving channels; Step 3.3: Calculate the sum channel data, azimuth difference channel data, and pitch difference channel data for the four receiving channels.

[0022] Step 4 specifically includes: Step 4.1: Set up at least two auxiliary antennas to form a clutter receiving space, and receive the echo of the interference signal through the auxiliary antennas; Step 4.2: Perform range-direction pulse compression on the interference signal echo; Step 4.3: Calculate the interference suppression weights based on the interference signal echo and the single pulse echo of the moving target, and use the interference suppression weights to suppress interference in the azimuth channel data, pitch difference channel data, and azimuth difference channel data.

[0023] For amplitude-comparison single-pulse and differential angle measurement techniques, the signals received by each receiving channel are echo signals with different amplitudes but the same phase. For moving targets, the target echoes received by different receiving channels of a multi-channel SAR radar system have a certain phase difference. After range pulse compression, phase correction is required to meet the amplitude-comparison single-pulse angle measurement conditions. The phase correction function is: ; Where: H represents the phase correction function with the data from the first received channel as the reference channel; j represents the imaginary unit; Indicates the slant range of the moving target relative to the receiving channel; This represents the slant range of the moving target relative to the first receiving channel; represents the signal carrier frequency; c represents the electromagnetic wave propagation speed.

[0024] The sum of the channel data for the four receiving channels is as follows: ; in: This represents the sum of data from the four receiving channels; This indicates the data received from the first channel; This indicates the data from the second receiving channel; This indicates the data received from the third channel; This indicates the data from the fourth receiving channel; Indicates distance in advance; The azimuth difference channel data of the four receiving channels are as follows: ; in: This represents the azimuth difference channel data of the four receiving channels; This indicates the data received from the first channel; This indicates the data from the second receiving channel; This indicates the data received from the third channel; This indicates the data from the fourth receiving channel; Indicates distance in advance; The pitch difference channel data of the four receiving channels are as follows: ; in: This represents the pitch difference channel data for the four receiving channels; This indicates the data received from the first channel; This indicates the data from the second receiving channel; This indicates the data received from the third channel; This indicates the data from the fourth receiving channel; Indicates distance in terms of fast time.

[0025] like Figure 2 and Figure 3As shown, an array coordinate system is established with the transmitting antenna of the multi-channel SAR radar system as the origin. The four receiving channels are located in the four quadrants of the array coordinate system, and each receiving channel consists of at least 80 array elements forming a rectangular array. Within each quadrant, 10 array elements are evenly distributed along the x-axis, and 8 array elements are evenly distributed along the y-axis, for a total of 80 array elements distributed within each quadrant.

[0026] Taking two adjacent array elements on the y-axis as an example, the path difference between the moving target and the two adjacent array elements is: Then the guiding vector along the y-axis can be expressed as: ; Where K=8 is the number of array elements in a single channel along the y-axis; j represents the imaginary part of the complex number; d represents the spacing between two adjacent array elements; This indicates the elevation angle at which the radar system observes a moving target. Indicates the elevation angle of the radar beam; Indicates the wavelength of the beam; This represents the guiding vector of the moving target along the y-axis.

[0027] Similarly, the guiding vector of the array on the x-axis can be obtained as: ; Where L=10 is the number of array elements in a single channel along the x-axis; j represents the imaginary part of the complex number; d represents the spacing between two adjacent array elements; This indicates the elevation angle at which the radar system observes a moving target. Indicates the elevation angle of the radar beam; Indicates the azimuth angle of a moving target observed by the radar system; Indicates the azimuth angle of the radar beam; Indicates the wavelength of the beam; This represents the guiding vector of the moving target along the x-axis.

[0028] The beam pattern of the area array beam of each receiving channel in a multi-channel SAR radar system is represented as follows: ; in: This indicates the radiation pattern of the area array beam; This represents the element radiation pattern after weighting the receiving antenna. This represents the guidance vector of the moving target along the y-axis. This represents the guiding vector of the moving target along the x-axis.

[0029] and ;in Represents the array element pattern function; Indicates the weighting coefficient of the receiving antenna; in ; ; Where: K represents the number of array elements in a single channel along the y-axis; This represents the element spacing along the x-axis of the array; This represents the element spacing along the y-axis of the array; This represents the weighted window function of the array along the x-axis. This represents the weighted window function of the array along the y-axis.

[0030] Based on the pattern function calculated above, let When the target angle With beam pointing angle satisfy The pitch angle error function can be calculated. for: ; in: This represents pitch difference channel data; This represents pitch and channel data, when the pitch angle error function... satisfy At that time, pitch angle error function It has a linear relationship with the pitch angle. This is the half-power beamwidth. Therefore, the elevation aberration slope can be expressed as: ; in: Indicates the pitch difference slope; .

[0031] Similarly, the azimuth angle error function can be obtained. and azimuth slope They can be represented as follows: ; in: This represents the azimuth difference channel data; This indicates the azimuth and channel data.

[0032] ; in: Indicates the azimuth slope; .

[0033] The formula for calculating the interference suppression weight is: ; in: Indicates the interference suppression weights; Represents the interference signal echo matrix; A single pulse echo matrix representing a moving target.

[0034] The formula for interference suppression using interference suppression weights on the azimuth channel data, pitch channel data, and other channel data is as follows: ; in: This represents the output result of interference suppression performed using interference suppression weight pairs and channel data, azimuth aberration channel data, and pitch aberration channel data. Indicates the interference suppression weights; Represents the interference signal echo matrix; A single pulse echo matrix representing a moving target.

[0035] The SAR multi-channel moving target detection method based on two-dimensional sum-difference angle measurement technology is implemented using amplitude comparison and difference angle measurement techniques. After the multi-channel SAR radar system transmits a linear frequency modulated (LFM) signal, the four receiving channels simultaneously receive the echo signals from the moving target, as shown in the following equation: ; Where: n is the receiving channel number, and n = 1, 2, 3, 4; For transmitting signal carrier frequency; The speed of electromagnetic wave propagation; For distance to fast time; The direction is slowed down by time; For pattern functions; The azimuth angle of the target relative to the phase center of the receiving channel; The pitch angle of the moving target relative to the phase center of the receiving channel; This is an interference signal; Let be the slant range of the moving target relative to the receiving channel; j is the imaginary part of the complex number.

[0036] The formula for calculating the slant distance of the moving target relative to the receiving channel is: ; in: Indicates the slant range of the moving target relative to the receiving channel; () represents the three-dimensional coordinates of the m-th moving target; () represents the three-dimensional coordinates of the nth receiving channel, 1≤n≤4; Indicates the azimuth velocity of a moving target; Represents the radial velocity of a moving target; This indicates the speed of movement of the multi-channel SAR radar system.

[0037] The azimuth slope was calculated using the above methods for calculating elevation and azimuth slopes. and pitch slope Then the moving target is relative to the direction of the digital beam. The angle can be calculated using the following formula: ; ; When the relative angle of the moving target is small, it can be approximately calculated using the following formula: ; .

[0038] Example 2: like Figures 9-16 As shown in the figure, the data obtained after simulation calculation using a multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in a clutter environment is as follows: Simulation Experiment Data Parameter Table

[0039] Detection of a single moving target: This method was used to conduct a simulation experiment on a single moving target. The parameters of the multi-channel SAR radar system are shown in the table above. The array radiation pattern after weighting the antenna pattern describes the normalized sum and difference beam patterns in the azimuth and elevation directions, respectively. Consider a moving target and three interference signals. The moving target's position is (100, 100, -H), and its radial velocity is -10 m / s, while its azimuth velocity is -15 m / s.

[0040] After phase correction and range pulse compression of the echo, interference suppression is performed using an auxiliary antenna. The results before and after interference suppression within a single pulse show that the interference is effectively suppressed. Figure 11 and Figure 12 The image shows the detection results of a SAR multi-channel moving target detection method based on two-dimensional sum-difference angle measurement technology in a cluttered environment. Figure 11 For theoretical calculation of test results, Figure 12 The results show the detection results of the method of the present invention on moving targets. The results demonstrate that the method of the present invention can detect moving targets, and the detection results are close to the theoretical calculation results.

[0041] Figure 13 and Figure 14 The estimation results of the azimuth and pitch angles by the method of this invention are compared with the theoretically calculated two-dimensional angle values. Figure 13 The difference between the theoretically calculated azimuth angle based on 128 pulses and the azimuth angle estimated by the method of this invention is given. Figure 14The difference between the pitch angle calculated theoretically and the pitch angle estimated by the method of this invention is used to calculate the pitch angle. The maximum error of the azimuth angle measurement by the method of this invention is 0.07261°, and the maximum error of the pitch angle measurement is 0.05963°. The two-dimensional angle measurement errors are both less than 0.1°, which meets the angle measurement requirements.

[0042] Example 3: like Figures 17-24 As shown, this demonstrates the detection of multiple moving targets: Simulation Experiment Data Parameter Table

[0043] Considering two moving targets and three interference signals, the initial positions of the two moving targets are (106, 106, -H) and (48, 52, -H). The initial angles of the two targets are calculated from their positions. The two-dimensional velocities of the moving target are (1.0168°, 1.0634°) and (0.5024°, 0.5097°), respectively. They are (-10m / s, -15m / s) and (-12m / s, -15m / s) respectively.

[0044] The above method was used to conduct a simulation experiment on two moving targets, such as... Figure 18 As shown, the interference suppression results are illustrated, and it can be seen that the interference is completely suppressed and the moving target signal is preserved. Figure 19 and Figure 20 The image shows the detection results of two moving targets using a SAR multi-channel moving target detection method based on two-dimensional sum-difference angle measurement technology in a cluttered environment. Figure 19 For the theoretically calculated detection effect, Figure 20 As the detection results of the method of the present invention are obvious, the detection results of the invented method are the same as the theoretically calculated detection results.

[0045] To further analyze the effects of the method of the present invention, Figure 21 and Figure 22 To compare the azimuth and pitch angle measurement results of moving targets using theoretical calculations and the method of this invention, the figure shows that the method of this invention can estimate the two-dimensional angles of multi-point moving targets, but there are certain errors between the estimated two-dimensional angles and the theoretically calculated angles. For moving target 1, the maximum azimuth angle error is 0.07693°, and the maximum pitch angle error is 0.004876°; for moving target 2, the maximum azimuth angle error is 0.08441°, and the maximum pitch angle error is 0.085318°. The differences between the estimated azimuth and pitch angles and the theoretically calculated values ​​are both less than 0.1°, meeting the resolution requirements.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in cluttered environments, implemented using a multi-channel SAR radar system, characterized in that... Includes the following steps: Step 1: Calculate the radiation pattern function of the array antenna of the multi-channel SAR radar system based on the range of azimuth and elevation angles, and calculate the azimuth difference slope and elevation difference slope based on the radiation pattern function. Step 2: Receive single pulse echoes from moving targets using a multi-channel SAR radar system, and perform range pulse compression on the single pulse echoes from moving targets; Step 3: Generate range pulse compression results and channel data, azimuth difference channel data, and elevation difference channel data based on the single pulse echoes of moving targets received by different channels in the multi-channel SAR radar system; Step 4: Receive clutter echoes through an auxiliary antenna, and suppress interference on the range pulse compression results of the clutter echoes for the sum channel data, azimuth difference channel data, and elevation difference channel data generated in Step 3. Step 5: Based on the results of Step 1 and Step 4, estimate the azimuth and pitch angles of the moving target, and perform one-dimensional CFAR detection on the estimation results. Step 6: Determine the number of moving targets. For a single moving target, directly calculate the pulse compression position of the azimuth and pitch angles of the single moving target. For multiple moving targets, a clustering method is used to extract the pulse compression position of each moving target; Step 7: Determine the azimuth and pitch angles of the moving target based on the pulse compression position, and plot the determined azimuth and pitch angles onto a two-dimensional angle grid.

2. The multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in a cluttered environment according to claim 1, characterized in that, Step 4 specifically includes: Step 4.1: Set up at least two auxiliary antennas to form a clutter receiving space, and receive the echo of the interference signal through the auxiliary antennas; Step 4.2: Perform range-direction pulse compression on the interference signal echo; Step 4.3: Calculate the interference suppression weights based on the interference signal echo and the single pulse echo of the moving target, and use the interference suppression weights to suppress interference in the azimuth channel data, pitch difference channel data, and azimuth difference channel data.

3. The multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in a cluttered environment according to claim 2, characterized in that, The formula for calculating the interference suppression weight is: Where: w opt denoted by ; N(t) represents the interference suppression weight; s(t) represents the interference signal echo matrix; s(t) represents the single pulse echo matrix of the moving target.

4. The multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in a cluttered environment according to claim 3, characterized in that, The formula for interference suppression using interference suppression weights on the azimuth channel data, pitch channel data, and other channel data is as follows: y out =s(t)-w opt N(t); Where: y out This represents the output result of interference suppression performed using interference suppression weight pairs and channel data, azimuth aberration channel data, and pitch aberration channel data; w opt denoted by ; N(t) represents the interference suppression weight; s(t) represents the interference signal echo matrix; s(t) represents the single pulse echo matrix of the moving target.

5. The multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in a cluttered environment according to any one of claims 1-4, characterized in that, Step 3 specifically includes: Step 3.1: Set up four receiving channels in the multi-channel SAR radar system to simultaneously receive single pulse echoes from moving targets through the four receiving channels; Step 3.2: Apply a phase correction function to correct the phase of the single pulse echo of the moving target received by the four receiving channels; Step 3.3: Calculate the sum channel data, azimuth difference channel data, and pitch difference channel data for the four receiving channels.

6. The multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in a cluttered environment according to claim 5, characterized in that, The phase correction function is: Where: H represents the phase correction function with the data from the first received channel as the reference channel; j represents the imaginary unit; R n R1 represents the slant range of the moving target relative to the receiving channel; R1 represents the slant range of the moving target relative to the first receiving channel; f c represents the signal carrier frequency; c represents the electromagnetic wave propagation speed.

7. The multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in a cluttered environment according to claim 6, characterized in that, The formula for calculating the slant distance of the moving target relative to the receiving channel is: Where: R n Indicates the slant range of the moving target relative to the receiving channel; (x m y m , z m (x) represents the three-dimensional coordinates of the m-th moving target; (x) n y n , z n () represents the three-dimensional coordinates of the nth receiving channel, 1≤n≤4; v a Indicates the azimuth velocity of a moving target; v r v0 represents the radial velocity of the moving target; v0 represents the velocity of the multi-channel SAR radar system.

8. The multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in a cluttered environment according to claim 7, characterized in that, The sum of the channel data for the four receiving channels is as follows: S ∑ (t r )=S1(t r )+S2(t r )+S3(t r )+S4(t r ); Wherein: S ∑ (t r S1(t) represents the sum of data from the four received channels; r S2(t) represents the data from the first received channel; r S3(t) represents the data from the second receiving channel; r S4(t) represents the data from the third receiving channel; r ) represents the data from the fourth receiving channel; t r Indicates distance in advance; The azimuth difference channel data of the four receiving channels are as follows: S (Δ , θ) (t r )=S1(t r )+S4(t r )-S2(t r )-S3(t r ); Wherein: S (Δ , θ) (t r S1(t) represents the azimuth difference channel data of the four receiving channels; r S2(t) represents the data from the first received channel; r S3(t) represents the data from the second receiving channel; r S4(t) represents the data from the third receiving channel; r ) represents the data from the fourth receiving channel; t r Indicates distance in advance; The pitch difference channel data of the four receiving channels are as follows: in: This represents the pitch difference channel data from the four receiving channels; S1(t) r S2(t) represents the data from the first received channel; r S3(t) represents the data from the second receiving channel; r S4(t) represents the data from the third receiving channel; r ) represents the data from the fourth receiving channel; t r Indicates distance in terms of fast time.

9. The multi-channel moving target detection method based on two-dimensional sum-difference angle measurement in a cluttered environment according to claim 8, characterized in that, An array coordinate system is established with the transmitting antenna of the multi-channel SAR radar system as the origin. The four receiving channels are located in the four quadrants of the array coordinate system, and each receiving channel consists of at least 80 array elements forming a rectangular array.

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