A radar fine-scan angle measurement method and apparatus based on inter-frame dual-parameter fitting correlation

Abstract

This invention belongs to the field of radar angle measurement and discloses a radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation. The method includes: obtaining multi-frame range Doppler images from radar echo data; obtaining a preliminary processed image using amplitude thresholding; obtaining a peak point map from the preliminary processed image by extracting local maxima points from the four nearest neighbors; calculating the angle error corresponding to non-zero points in the peak point map of each frame using the sum-difference method; obtaining the beam azimuth angle of the corresponding frame from the radar echo data; obtaining a set of measurement values ​​based on the beam azimuth angle, angle error, and pixel position of all frames; obtaining a superimposed image from the peak point maps of all frames; detecting targets in the superimposed image using a preset occurrence threshold; for each target, indexing the angle error and beam azimuth angle in the measurement value set, linearly fitting using the least squares criterion, and obtaining the angle measurement value of the target using the fitted line. This invention can improve the angle measurement accuracy in small-range search and sector-scan tracking scenarios.

Description

Technical Field

[0001] This invention belongs to the field of radar angle measurement, specifically relating to a radar fine scanning angle measurement method and apparatus based on inter-frame dual-parameter fitting correlation. Background Technology

[0002] As a crucial tool for target detection, radar has played an increasingly important role in both military and civilian fields in recent years. Radar needs to detect various types of target information, and its most basic function is to detect targets by utilizing their reflection of electromagnetic waves, thereby determining their spatial location, which includes range and azimuth. Measuring the target's azimuth has always been one of the most fundamental and important functions of radar; therefore, accurately measuring the target's azimuth angle is a crucial step in radar signal processing and a key issue in signal processing itself.

[0003] Monopulse radar is widely used in target tracking due to its high angle measurement accuracy. Currently, most modern radars use monopulse technology to estimate the target's direction of arrival, operating with only one pulse. Measurement methods are divided into phase methods and amplitude methods. The phase method uses the phase difference between the echo signals received by multiple antennas to measure the angle, while the amplitude method uses the amplitude value of the radar echo signal received by the antenna to measure the angle.

[0004] Current technologies directly use the angle discrimination curve (or angle discrimination curve) to measure angles during small-range searches and sector scanning. However, in practice, the angle discrimination curve is not a straight line due to fluctuations in the target signal-to-noise ratio under ocean background conditions. Figure 1 As shown, directly using the angle corresponding to the angle discrimination curve will result in a large dispersion distribution in the target angle dimension. In addition, the angle channel gain is affected by factors such as temperature, which will change the slope of the angle discrimination curve, also causing the corresponding angle error to increase. Figure 2 As shown. Obtaining high-precision angle measurement results in these situations requires accurate compensation of the angle discrimination curve, which is time-consuming and labor-intensive, and places high demands on the echo signal-to-noise ratio, resulting in low angle measurement accuracy under outdoor conditions.

[0005] Therefore, there is an urgent need to provide effective solutions to the problems that existing radar angle measurement methods cannot effectively cope with changes in the slope of the angle discrimination curve caused by various reasons, as well as the low accuracy and instability of angle measurement in complex scenarios. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a radar fine-scan angle measurement method and apparatus based on inter-frame dual-parameter fitting correlation. The technical problem to be solved by this invention is achieved through the following technical solution:

[0007] In a first aspect, embodiments of the present invention provide a radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation, the method comprising:

[0008] Based on the received radar echo data, multiple range Doppler images are obtained. Each range Doppler image is processed using an amplitude threshold to obtain the corresponding preliminary processed image.

[0009] For each frame of the initial image processing, the local maxima are extracted by four nearest neighbors to obtain the corresponding peak point map;

[0010] The sum-difference method is used to calculate the angular error corresponding to the non-zero point in the peak point map of each frame; the beam azimuth angle of the corresponding frame is obtained from the radar echo data; based on the beam azimuth angle of all frames within the scanning range, the angular error obtained from the peak point map, and the pixel position, a set of measurement values ​​is obtained.

[0011] The peak point maps of all frames within the scanning range are superimposed to obtain a superimposed image; the target in the superimposed image is detected using a preset occurrence frequency threshold;

[0012] For each target, the corresponding angular error and beam azimuth angle are indexed in the set of measurements;

[0013] For each target, all indexed angular errors and beam azimuth angles are linearly fitted using the least squares criterion to obtain the fitted line of the target; the angle measurement value of the target is obtained using the fitted line corresponding to the target.

[0014] Secondly, embodiments of the present invention provide a radar fine-scan angle measurement device with inter-frame dual-parameter fitting correlation, the device comprising:

[0015] The preliminary image acquisition module is used to obtain multiple frames of range Doppler images based on the received radar echo data, and to process each frame of range Doppler image using an amplitude threshold to obtain the corresponding preliminary processed image.

[0016] The peak point map acquisition module is used to obtain the corresponding peak point map by extracting local maxima points from the four nearest neighbors of each frame of the pre-processed image.

[0017] The measurement value set acquisition module is used to calculate the angular error corresponding to the non-zero point in the peak point map of each frame using the sum and difference method; obtain the beam azimuth angle of the corresponding frame from the radar echo data; and obtain the measurement value set based on the beam azimuth angle of all frames within the scanning range, the angular error obtained from the peak point map, and the pixel position.

[0018] The target filtering module is used to overlay the peak point maps of all frames within the scanning range to obtain an overlay image; and to detect targets in the overlay image using a preset occurrence threshold.

[0019] The target information indexing module is used to index the corresponding angular error and beam azimuth angle in the set of measured values ​​for each target.

[0020] The target angle measurement module is used to perform linear fitting on all indexed angle errors and beam azimuth angles for each target using the least squares criterion to obtain the target's fitted line; the target's angle measurement value is obtained using the fitted line corresponding to the target.

[0021] The beneficial effects of this invention are:

[0022] This invention provides a radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation. It integrates information obtained from multiple target measurements during scanning, uses the least squares method to linearly fit the target angle error and the beam azimuth angle of the corresponding frame number, and performs angle measurement based on the zero-crossing point of the fitted line. Since it does not use the slope information of the angle discrimination curve, this method is insensitive to changes in the gain of the sum and difference channels, enhancing the system's adaptability under practical operating conditions. Because it specifically uses the zero-crossing point fitted from multiple frames of information for angle measurement, it effectively reduces the impact of target signal-to-noise ratio fluctuations, improves target angle cohesion during small-range search and sector-scan tracking, and significantly improves target clustering accuracy. The angle measurement accuracy obtained by this method can reach similar levels to closed-loop tracking, effectively improving angle measurement accuracy. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the insufficient linearity of the existing angle-detection curve.

[0024] Figure 2 This is a schematic diagram illustrating the slope variation of the existing angle-recognition curve;

[0025] Figure 3 This is a flowchart illustrating a radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation provided in an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram comparing the angle-matching curve before and after fitting in an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram illustrating the calculation of the target's angle measurement value according to an embodiment of the present invention;

[0028] Figure 6 In this embodiment of the invention, the target angle measurement results within the scene before processing are obtained during a small-scale search operation.

[0029] Figure 7 This is the result of angle measurement of the target within the scene after processing during a small-scale search operation in an actual embodiment of the present invention.

[0030] Figure 8This is a detailed flowchart illustrating a radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation provided in an embodiment of the present invention.

[0031] Figure 9 This is a schematic diagram of a radar fine scanning angle measurement device with inter-frame dual-parameter fitting correlation provided in an embodiment of the present invention. Detailed Implementation

[0032] 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.

[0033] In a first aspect, embodiments of the present invention provide a radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation, such as... Figure 3 As shown, the method may include the following steps:

[0034] S1. Obtain multiple range Doppler images based on the received radar echo data. Process each range Doppler image using an amplitude threshold to obtain the corresponding preliminary processed image.

[0035] Specifically, let the scanning range be from frame n1 to frame n. Q The range-Doppler image of the nth frame can be obtained from the received radar echo data. n The dimension of each frame of the distance Doppler image is M×N, with the horizontal axis representing the distance dimension and the vertical axis representing the Doppler dimension, where M and N are natural numbers greater than 0, and Q is a natural number greater than 1.

[0036] The process of processing each frame of the distance Doppler image using an amplitude threshold to obtain the corresponding preliminary processed image uses the following calculation formula:

[0037]

[0038] Where n represents the frame number corresponding to the distance Doppler image; I Σn (i,j) represents the amplitude of the range Doppler image at position (i,j) in the nth frame of the range Doppler image; Q is a natural number greater than 1, representing the total number of frames of the range Doppler image to be processed; g represents the amplitude threshold; I tn (i,j) represents the pixel value at position (i,j) in the initial processed image of the nth frame; A Nn Let represent the noise floor of the nth frame, whose main source is thermal noise, which follows a Gaussian distribution. The calculation formula used is:

[0039] A Nn =mod(round(I Σn )) (2);

[0040] In this context, mod(·) takes the mode, which is the value that appears most frequently; round(·) rounds the integer to the nearest whole number.

[0041] The amplitude can be used for the first step of target detection. It can be understood that each frame of distance Doppler image can be processed to obtain a corresponding preliminary processed image. The noise floor is removed, and the positions with amplitude less than the amplitude threshold are set to 0.

[0042] S2, for each frame of the preliminary image, the local maxima are extracted by four nearest neighbors to obtain the corresponding peak point map;

[0043] In this process, the initial image processing of each frame extracts local maxima points using the four nearest neighbors method to obtain the corresponding peak point map. The calculation formula used is as follows:

[0044]

[0045] SGN=sgn(4I tn (i,j)-I tn (i-1,j)-I tn (i+1,j)-I tn (i,j-1)-I tn (i,j+1)) (3);

[0046] i = 2, ..., M-1, j = 2, ..., N-1

[0047] Where SGN is the simplified representation of the above sgn() formula; sgn(·) is the sign function, I pn (i,j) represents the pixel value of the peak point image at position (i,j) in the nth frame; M is the number of rows in the initial processed image, and N is the number of columns in the initial processed image.

[0048] As can be understood from formula (3), the pixel value at position (i,j) in the peak point image of the nth frame is determined by using the pixel values ​​at position (i,j) and its four positions above, below, left, and right in the preliminary processed image of the nth frame.

[0049] Local peak points have a higher signal-to-noise ratio compared to other adjacent points, which is more conducive to obtaining more accurate results when measuring target parameters.

[0050] S3, use the sum-difference method to calculate the angular error corresponding to the non-zero point in the peak point map of each frame; obtain the beam azimuth angle of the corresponding frame from the radar echo data; based on the beam azimuth angle of all frames within the scanning range, the angular error obtained from the peak point map, and the pixel position, obtain the set of measurement values;

[0051] In S3, the calculation formula used to calculate the angular error corresponding to the non-zero points in the peak point map of each frame using the sum-difference method is as follows:

[0052]

[0053] Among them, I Δn (i,j) represents the amplitude of the distance Doppler image of the nth frame of the difference channel at position (i,j); ε n (i,j) represents the angular error of the sum and difference channels in the nth frame at position (i,j) in the Doppler image.

[0054] It is understandable that for the peak point map of the nth frame, each non-zero point, that is, the point with a pixel value of 1, can obtain a corresponding angular error.

[0055] For a given angular error, the corresponding beam azimuth angle, denoted as AZ, can be obtained from the radar echo data based on the frame number used in its calculation and the pixel position in the corresponding frame's range-Doppler image. Therefore, for a target location, both the angular error and the beam azimuth angle can be obtained as measurement results. Thus, it can be understood that by combining the beam azimuth angles of all frames within the scanning range, the angular error obtained from the peak point map, and the pixel position, a set of measurement values ​​T = {ε} can be obtained. m ,AZ m i m ,j m}, where ε m AZ m These are the angular error and corresponding beam azimuth angle of the m-th measurement result, respectively. m j m This represents the pixel position corresponding to the m-th measurement result.

[0056] S4, superimpose the peak point maps of all frames within the scanning range to obtain a superimposed image; detect the target in the superimposed image using a preset occurrence threshold;

[0057] All peak point images within the scanned range are processed by superimposing the pixel values ​​at the same pixel location to obtain a superimposed image, denoted as I. sum .

[0058] The embodiments of the present invention have a preset occurrence threshold, denoted as H, where H is a natural number greater than 0, and is set according to empirical values.

[0059] The method of detecting targets in the overlay image using a preset occurrence frequency threshold includes:

[0060] Pixels in the overlay image whose values ​​are greater than or equal to the occurrence threshold are taken as stable targets with sufficiently high signal-to-noise ratios, and the positions of the targets in the overlay image are determined.

[0061] The process of object detection in the superimposed image described above can be understood by referring to the following formula:

[0062] D={i,j|I sum (i,j)≥H} (5);

[0063] Among them, I sum (i,j) represents the value at position (i,j) in the overlay image; D represents the set of target positions.

[0064] Understandably, the above processing can detect one or more targets, as well as the location of each target.

[0065] S5, for each target, index the corresponding angular error and beam azimuth angle in the set of measured values;

[0066] Specifically, for each target, indexing the corresponding angular error and beam azimuth angle in the set of measurements includes:

[0067] For each target, using the target's position in the overlay image, the angular error and beam azimuth angle that match the pixel position are indexed in the set of measurements, which are then used as all the angular errors and beam azimuth angles indexed for that target.

[0068] Specifically, based on the position D of the target p (p = 1, 2, ... P) in the overlay image... p Index the m-th value in the set of measured values ​​T p (m p =m p1 ,…,m pV Each piece of information includes the corresponding angular error and beam azimuth angle. Here, P represents the total number of detected targets, and pV represents the total number of measurement values ​​matched for the p-th target. In other words, for a single target, multiple angular errors and beam azimuth angles can be obtained.

[0069] S6. For each target, the least squares criterion is used to perform linear fitting on all indexed angular errors and beam azimuth angles to obtain the target's fitted line; the angle measurement value of the target is obtained using the fitted line corresponding to the target.

[0070] S6 is performed for each target. For each target, the least squares criterion is used to perform linear fitting on all angular errors and beam azimuth angles indexed to that target, resulting in a fitted straight line for that target. This is a process of solving an optimization problem, which can be expressed as:

[0071]

[0072] Where h represents the function of the optimization problem; P represents the total number of detected targets; pV represents the total number of measurement information points matched by the p-th target, i.e., how many information points are indexed in the measurement value set T; ε m AZ m These represent the angular error and corresponding beam azimuth angle of the m-th measurement result, respectively; k p and b p The parameters of the fitted line for the p-th target can be determined by solving for them. In k... p and b p Once the solution is determined, the fitted line for the p-th objective is determined.

[0073] Therefore, for each objective, k is determined. p and b p Then, the fitted curve for the target can be determined.

[0074] This invention uses the least squares method to process the angular error of the target, which can comprehensively analyze the results obtained from multiple measurements of the target during scanning, and compare the results before and after angular curve fitting. Figure 4 As shown, this improves the accuracy of target angle measurement during small-range search and sector scanning, mitigating the adverse effects of target signal-to-noise ratio fluctuations and changes in the slope of the angle discrimination curve on angle measurement accuracy.

[0075] For details on the process of linear fitting using the least squares criterion, please refer to the relevant technical explanations; it will not be elaborated here.

[0076] The horizontal axis of the fitted straight line represents the beam azimuth angle, and the vertical axis represents the angular error. Therefore, for each target, obtaining the target's angle measurement value using the fitted straight line includes:

[0077] The angle corresponding to the zero point on the fitted line of the target is obtained as the angle measurement value of the target.

[0078] Specifically, the angle corresponding to the zero point of the fitted line can be calculated. As the angle measurement value of the target p, such as Figure 5 As shown.

[0079] In actual small-scale search operations, the target angle measurement results before and after processing are as follows: Figure 6 and Figure 7 As shown in the figure. The RDA plot represents the distance-Doppler angle plot.

[0080] The radar fine-scan angle measurement method based on inter-frame dual-parameter fitting and correlation provided in this invention integrates information obtained from multiple target measurements during scanning to achieve target angle measurement. Detailed processing flow can be found in [link to relevant documentation]. Figure 8 I understand; I will not go into the specifics.

[0081] Since multiple samplings are performed during small-range search and sector scan tracking, sufficient measurement information can be obtained for the same target. Based on this, this invention provides a radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation. It integrates information obtained from multiple target measurements during scanning, uses the least squares method to linearly fit the target angle error and the beam azimuth angle of the corresponding frame number, and performs angle measurement based on the zero-crossing point of the fitted line. Because it does not use the slope information of the angle discrimination curve, this method is insensitive to changes in the sum and difference channel gain, enhancing the system adaptability under actual working conditions. By specifically using the zero-crossing point fitted from multiple frames for angle measurement, it effectively reduces the impact of target signal-to-noise ratio fluctuations, improves target angle cohesion during small-range search and sector scan tracking, and significantly improves target clustering accuracy. The angle measurement accuracy obtained by this method can reach similar levels to closed-loop tracking, effectively improving angle measurement accuracy.

[0082] Secondly, corresponding to the above method embodiments, this invention also provides a radar fine-scan angle measurement device with inter-frame dual-parameter fitting correlation, such as... Figure 9 As shown, the device includes:

[0083] The preliminary image acquisition module is used to obtain multiple frames of range Doppler images based on the received radar echo data, and to process each frame of range Doppler image using an amplitude threshold to obtain the corresponding preliminary processed image.

[0084] The peak point map acquisition module is used to obtain the corresponding peak point map by extracting local maxima points from the four nearest neighbors of each frame of the pre-processed image.

[0085] The measurement value set acquisition module is used to calculate the angular error corresponding to the non-zero point in the peak point map of each frame using the sum and difference method; obtain the beam azimuth angle of the corresponding frame from the radar echo data; and obtain the measurement value set based on the beam azimuth angle of all frames within the scanning range, the angular error obtained from the peak point map, and the pixel position.

[0086] The target filtering module is used to overlay the peak point maps of all frames within the scanning range to obtain an overlay image; and to detect targets in the overlay image using a preset occurrence threshold.

[0087] The target information indexing module is used to index the corresponding angular error and beam azimuth angle in the set of measured values ​​for each target.

[0088] The target angle measurement module is used to perform linear fitting on all indexed angle errors and beam azimuth angles for each target using the least squares criterion to obtain the target's fitted line; the target's angle measurement value is obtained using the fitted line corresponding to the target.

[0089] Optionally, for the preliminary image acquisition module, each frame of the distance Doppler image is processed using an amplitude threshold to obtain the corresponding preliminary image. The calculation formula used is as follows:

[0090]

[0091] Where n represents the frame number corresponding to the distance Doppler image; I Σn (i,j) represents the amplitude of the range Doppler image at position (i,j) in the nth frame of the range Doppler image; Q is a natural number greater than 1, representing the total number of frames of the range Doppler image to be processed; g represents the amplitude threshold; I tn (i,j) represents the pixel value at position (i,j) in the initial processed image of the nth frame; A Nn The noise floor of the nth frame is represented by the following formula:

[0092] A Nn =mod(round(I Σn ));

[0093] In this context, mod(·) is used to select the modulo; round(·) is used to round to the nearest integer.

[0094] Optionally, for the peak point map acquisition module, the corresponding peak point map is obtained by extracting local maxima points from the four nearest neighbors for each frame of the pre-processed image. The calculation formula used is as follows:

[0095]

[0096] SGN=sgn(4I tn (i,j)-I tn (i-1,j)-I tn (i+1,j)-I tn (i,j-1)-I tn (i,j+1));

[0097] i = 2, ..., M-1, j = 2, ..., N-1

[0098] Where sgn(·) is the sign function, I pn (i,j) represents the pixel value of the peak point image at position (i,j) in the nth frame; M is the number of rows in the initial processed image, and N is the number of columns in the initial processed image.

[0099] Optionally, for the module obtaining the set of measured values, the angular error corresponding to the non-zero points in the peak point image of each frame is calculated using the sum-difference method, and the calculation formula is as follows:

[0100]

[0101] Among them, I Δn (i,j) represents the amplitude of the distance Doppler image of the nth frame of the difference channel at position (i,j); ε n (i,j) represents the angular error of the sum and difference channels in the nth frame at position (i,j) in the Doppler image.

[0102] Optionally, for the target filtering module, a preset occurrence frequency threshold is used to detect targets in the overlay image, specifically for:

[0103] Pixels in the overlay image whose values ​​are greater than or equal to the occurrence threshold are taken as targets, and the positions of the targets in the overlay image are determined.

[0104] Optionally, for the target information indexing module, for each target, the corresponding angular error and beam azimuth angle are indexed in the set of measured values, specifically for:

[0105] For each target, using the target's position in the overlay image, the angular error and beam azimuth angle that match the pixel position are indexed in the set of measurements, which are then used as all the angular errors and beam azimuth angles indexed for that target.

[0106] Optionally, for the target angle measurement module, the process of linearly fitting all indexed angle errors and beam azimuth angles to obtain the target fitting line using the least squares criterion for each target can be represented by the following optimization problem:

[0107]

[0108] Where h represents the function of the optimization problem; P represents the total number of detected targets; pV represents the total number of measurement values ​​matched by the p-th target; ε m AZ m These represent the angular error and corresponding beam azimuth angle of the m-th measurement result, respectively; k p and b p Let k represent the parameters of the fitted line for the p-th target. p and b p Once the solution is determined, the fitted line for the p-th objective is determined.

[0109] Optionally, the angle measurement module for the target obtains the angle measurement value of the target by using the fitted straight line of the target, specifically for:

[0110] The angle corresponding to the zero point on the fitted line of the target is obtained as the angle measurement value of the target.

[0111] For details on the specific processing procedures of each module of the device, please refer to the relevant content in the first section, which will not be repeated here.

[0112] The radar fine-scan angle measurement device with inter-frame dual-parameter fitting correlation provided in this invention integrates information obtained from multiple target measurements during scanning, uses the least squares method to linearly fit the target angle error and the beam azimuth angle of the corresponding frame number, and performs angle measurement based on the zero-crossing point of the fitted line. Since it does not use the slope information of the angle discrimination curve, the method of this invention is insensitive to changes in the gain of the sum and difference channels, enhancing the system adaptability under actual working conditions. Because it specifically uses the zero-crossing point fitted from multiple frames of information for angle measurement, it effectively reduces the impact of target signal-to-noise ratio fluctuations, improves target angle cohesion during small-range search and sector-scan tracking, and significantly improves target clustering accuracy. The angle measurement accuracy obtained by the method of this invention can reach similar levels to closed-loop tracking, effectively improving angle measurement accuracy.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation, characterized in that, include: Based on the received radar echo data, multiple range Doppler images are obtained. Each range Doppler image is processed using an amplitude threshold to obtain the corresponding preliminary processed image. For each frame of the initial image processing, the local maxima are extracted by four nearest neighbors to obtain the corresponding peak point map; The sum-difference method is used to calculate the angular error corresponding to the non-zero points in the peak point image of each frame; Obtain the beam azimuth angle of the corresponding frame from the radar echo data; based on the beam azimuth angle of all frames within the scanning range, the angle error obtained from the peak point map, and the pixel position, obtain the set of measurement values; The peak point maps of all frames within the scanning range are superimposed to obtain a superimposed image; the target in the superimposed image is detected using a preset occurrence frequency threshold; For each target, the corresponding angular error and beam azimuth angle are indexed in the set of measurements; For each target, all indexed angular errors and beam azimuth angles are linearly fitted using the least squares criterion to obtain the fitted line of the target; the angle measurement value of the target is obtained using the fitted line corresponding to the target.

2. The radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation according to claim 1, characterized in that, The process of processing each frame of the distance Doppler image using an amplitude threshold to obtain the corresponding preliminary processed image uses the following calculation formula: Where n represents the frame number corresponding to the distance Doppler image; I Σn (i,j) represents the amplitude of the range Doppler image at position (i,j) in the nth frame of the range Doppler image; Q is a natural number greater than 1, representing the total number of frames of the range Doppler image to be processed; g represents the amplitude threshold; I tn (i,j) represents the pixel value at position (i,j) in the initial processed image of the nth frame; A Nn The noise floor of the nth frame is represented by the following formula: A Nn =mod(round(I Σn )); In this context, mod(·) is used to select the modulo; round(·) is used to round to the nearest integer.

3. The radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation according to claim 2, characterized in that, The initial image processing of each frame uses the method of extracting local maxima points from four nearest neighbors to obtain the corresponding peak point map. The calculation formula used is as follows: SGN=sgn(4I tn (i,j)-I tn (i-1,j)-I tn (i+1,j)-I tn (i,j-1)-I tn (i,j+1)); i = 2, ..., M-1, j = 2, ..., N-1 Where sgn(·) is the sign function, I pn (i,j) represents the pixel value of the peak point image at position (i,j) in the nth frame; M is the number of rows in the initial processed image, and N is the number of columns in the initial processed image.

4. The radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation according to claim 3, characterized in that, The formula used to calculate the angular error corresponding to the non-zero points in the peak point image of each frame using the sum-difference method is as follows: Among them, I Δn (i,j) represents the amplitude of the distance Doppler image of the nth frame of the difference channel at position (i,j); ε n (i,j) represents the angular error of the sum and difference channels in the nth frame at position (i,j) in the Doppler image.

5. The radar fine-scan angle measurement method based on inter-frame dual-parameter fitting and correlation according to claim 4, characterized in that, The method of detecting targets in the overlay image using a preset occurrence frequency threshold includes: Pixels in the overlay image whose values ​​are greater than or equal to the occurrence threshold are taken as targets, and the positions of the targets in the overlay image are determined.

6. The radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation according to claim 5, characterized in that, For each target, indexing the corresponding angular error and beam azimuth angle in the set of measurements includes: For each target, using the target's position in the overlay image, the angular error and beam azimuth angle that match the pixel position are indexed in the set of measurements, which are then used as all the angular errors and beam azimuth angles indexed for that target.

7. The radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation according to claim 6, characterized in that, The optimization problem in the process of linearly fitting all indexed angular errors and beam azimuth angles to obtain the target's fitted line using the least squares criterion is as follows: Where h represents the function of the optimization problem; P represents the total number of detected targets; pV represents the total number of measurement values ​​matched by the p-th target; ε m AZ m These represent the angular error and corresponding beam azimuth angle of the m-th measurement result, respectively; k p and b p Let k represent the parameters of the fitted line for the p-th target. p and b p Once the solution is determined, the fitted line for the p-th objective is determined.

8. The radar fine-scan angle measurement method based on inter-frame dual-parameter fitting correlation according to claim 1, characterized in that, The step of obtaining the angle measurement value of the target using the fitted straight line of the target includes: The angle corresponding to the zero point on the fitted line of the target is obtained as the angle measurement value of the target.

9. A radar fine-scan angle measurement device with inter-frame dual-parameter fitting correlation, characterized in that, include: The preliminary image acquisition module is used to obtain multiple frames of range Doppler images based on the received radar echo data, and to process each frame of range Doppler image using an amplitude threshold to obtain the corresponding preliminary processed image. The peak point map acquisition module is used to obtain the corresponding peak point map by extracting local maxima points from the four nearest neighbors of each frame of the pre-processed image. The measurement set acquisition module is used to calculate the angular error corresponding to the non-zero points in the peak point map of each frame using the sum and difference method; Obtain the beam azimuth angle of the corresponding frame from the radar echo data; based on the beam azimuth angle of all frames within the scanning range, the angle error obtained from the peak point map, and the pixel position, obtain the set of measurement values; The target filtering module is used to overlay the peak point maps of all frames within the scanning range to obtain an overlay image; and to detect targets in the overlay image using a preset occurrence threshold. The target information indexing module is used to index the corresponding angular error and beam azimuth angle in the set of measured values ​​for each target. The target angle measurement module is used to perform linear fitting on all indexed angle errors and beam azimuth angles for each target using the least squares criterion to obtain the target's fitted line; the target's angle measurement value is obtained using the fitted line corresponding to the target.

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