A multi-dimensional visualization analysis method for SAR detection capability

Abstract

The present invention discloses a multidimensional visualization analysis method for SAR detection capabilities, belonging to the field of synthetic aperture radar imaging technology. It solves the problem in the prior art that radar detection parameters are numerous and their coupling relationships are complex, making it impossible to perform a fusion analysis and display of the coupling relationships of the radar detection parameters and the detection boundaries. The method includes obtaining a ground reflection coefficient matrix, a range resolution matrix, and an azimuth resolution matrix for grid points at different range resolutions; screening the range resolution in the range resolution matrix, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix of the grid points according to a threshold range, obtaining multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient requirements, and graphically displaying them to obtain a two-dimensional analysis chart. This method can be used for multidimensional visualization analysis of SAR detection capabilities.

Description

Technical Field

[0001] The present invention belongs to the technical field of synthetic aperture radar imaging, and in particular relates to a multi-dimensional visualization analysis method for SAR detection capability. Background Art

[0002] SAR (Synthetic Aperture Radar) is an active earth observation system that can be installed on aircraft, satellites, spacecraft and other flying platforms to conduct earth observations around the clock and in all weather conditions, and has a certain surface penetration capability.

[0003] The increasing demand for high-precision SAR detection requires a thorough understanding of the coupling of various SAR detection parameters and the capability boundaries. The SAR detection parameters are numerous and the coupling relationships are complex, making detailed analysis difficult. Different detection requirements and usage scenarios lead to different detection boundary constraints. It is necessary to integrate the detection boundary constraints with the detection parameters for analysis and make the optimal decision for the SAR solution design under multi-task requirements.

[0004] Therefore, the existing technology is still unable to perform fusion analysis and display of the coupling relationship between SAR detection parameters and detection boundaries. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a multi-dimensional visualization analysis method for SAR detection capabilities, which solves the problem in the existing technology that radar detection parameters are numerous and the coupling relationships are complex, making it impossible to perform a fusion analysis and display of the coupling relationships of radar detection parameters and detection boundaries.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions:

[0007] The present invention provides a multi-dimensional visualization analysis method for SAR detection capability, comprising the following steps:

[0008] Step 1: Determine the ground beam coverage using the vehicle's flight parameters and the SAR's antenna installation angle and scanning range. Draw a grid within the beam coverage to obtain the grid point coordinate matrix within the beam coverage.

[0009] Step 2: Calculate the slant angle matrix and slant range matrix corresponding to the grid points within the beam coverage range based on the flight parameters of the carrier and the grid point coordinate matrix;

[0010] Step 3: Calculate the actual transmit gain matrix from the antenna to the grid point and the actual receive gain matrix from the antenna to the grid point based on the off-axis angle. It should be noted that the off-axis angle refers to the angle between the carrier target pointing and the antenna pointing;

[0011] Step 4: Calculate the SAR equation based on the actual transmission gain matrix from the antenna to the grid point, the actual receiving gain matrix from the antenna to the grid point, the slant angle matrix, the slant range matrix, the SAR system loss, and the average power to obtain the ground reflection coefficient matrix of the grid point at different distance resolutions;

[0012] According to the bandwidth of SAR, the height of the carrier and the slant range matrix, the range resolution matrix of the grid points is obtained;

[0013] According to the carrier's velocity, wavelength, synthetic aperture time, slant angle matrix and slant range matrix, the azimuth resolution matrix of the grid points is obtained;

[0014] The distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix are screened according to the threshold range to obtain multiple grid points that simultaneously meet the distance resolution, azimuth resolution, and ground reflection coefficient, and display them graphically to obtain a two-dimensional analysis diagram;

[0015] Step 5: Analyze the SAR detection capability based on the obtained two-dimensional analysis graph.

[0016] Furthermore, in step 1, the following method is used to obtain the grid point coordinate matrix within the beam coverage range:

[0017] T x =[x1,x2,…,x M ]

[0018] T z =[z1,z2,…,z N ]

[0019] Among them, x1, x M 、z1、z N are the coordinates of the intersection of the maximum coverage range of the beam and the two-dimensional coordinate axis of the ground, T x 、T z is the two-dimensional coordinate matrix of the grid points, x is an integer from 1 to M, and z is an integer from 1 to N.

[0020] Furthermore, in step 2, the slant angle matrix θ and slant range matrix R corresponding to the grid points within the beam coverage range are calculated based on the flight parameters of the carrier and the grid point coordinate matrix using the following formula:

[0021] θ v =arctan(v z / v x )

[0022] θ p =arctan(T z -P z ) / (Tx -P z )

[0023] θ=θ p -θ v

[0024]

[0025] Among them, θ is the slant angle matrix, R is the slant distance matrix, and v x is the north velocity of the carrier in the navigation coordinate system, v z is the east speed of the carrier in the navigation coordinate system, (P x , P y , P z ) is the coordinate of the carrier in the navigation coordinate system, T x 、T z is the two-dimensional coordinate matrix of the grid points, x is an integer from 1 to M, and z is an integer from 1 to N.

[0026] Furthermore, in step 3, according to the off-axis angle matrix Calculate the actual transmission gain matrix G from the antenna to the grid point tT And the actual receiving gain matrix G from the antenna to the grid point rT Use the following formula:

[0027]

[0028]

[0029] Among them, G t is the antenna transmission gain, G r G is the antenna receiving gain. Each model of GAR has a fixed G t and G r , both are known values, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, is the off-axis angle matrix.

[0030] Furthermore, in step 4, the SAR equation is calculated based on the actual transmission gain matrix from the antenna to the grid point, the actual receiving gain matrix from the antenna to the grid point, the slant angle matrix, the slant range matrix, the system loss of the SAR, and the average power, and the ground reflection coefficient matrix of the grid point at different resolutions is obtained using the following formula:

[0031]

[0032] Where σ is the ground reflection coefficient matrix, R is the slant range matrix, K = 1.38 × 10 -23is the Boltzmann constant, T0 is the noise temperature, F n is the noise coefficient, L is the system loss, v is the sum velocity of the carrier in the north-east plane in the navigation coordinate system, θ is the oblique viewing angle matrix, P av is the average power, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, SNR is the detection signal-to-noise ratio, λ is the wavelength, D r is the range resolution, and k=1.4 is the azimuth broadening factor.

[0033] Furthermore, in step 4, according to the bandwidth B of SAR r , the height of the carrier, the slant distance R matrix to calculate the distance resolution matrix D r Use the following formula:

[0034]

[0035]

[0036] Among them, D r is the distance resolution matrix, R is the slant range matrix, B r is the bandwidth of SAR, (P x , P y , P z ) is the coordinate of the carrier in the navigation coordinate system, k is the azimuth broadening factor, c is the speed of light, and β is the ground-grabbing angle.

[0037] Furthermore, in step 4, the azimuth resolution matrix D is calculated based on the carrier's velocity, wavelength, synthetic aperture time, slant angle matrix, and slant range matrix. a Use the following formula:

[0038]

[0039] Among them, D a is the azimuth resolution matrix, k is the azimuth broadening factor, λ is the wavelength, R is the slant range matrix, v is the sum velocity of the carrier in the northeast plane in the navigation coordinate system, θ is the slant angle matrix, T a is the synthetic aperture time.

[0040] Furthermore, in step 4, screening the distance resolution in the distance resolution matrix, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix of the grid points according to the threshold range includes the following steps:

[0041] At the same time, it is determined whether the distance resolution in the distance resolution matrix is ​​within the distance resolution threshold range, whether the azimuth resolution in the azimuth resolution matrix is ​​within the azimuth resolution threshold range, and whether the ground reflection coefficient in the ground reflection coefficient matrix is ​​within the ground reflection coefficient threshold range;

[0042] If the range resolution, azimuth resolution, and ground reflection coefficient are all within their respective threshold ranges, the grid points corresponding to the range resolution, azimuth resolution, and ground reflection coefficient are judged to meet the conditions, and multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient are obtained.

[0043] Furthermore, step 4 also includes the following steps:

[0044] Calculate the distortion rate based on the velocity error and height error of the carrier;

[0045] According to the threshold range, multiple grid points that simultaneously meet the range resolution, azimuth resolution and ground reflection coefficient are subjected to distortion screening, and the grid points after distortion screening are graphically displayed as grid points that meet the conditions.

[0046] Furthermore, calculating the distortion rate based on the velocity error and height error of the carrier includes the following steps:

[0047] The theoretical two-dimensional positions of the four edge points of the ground beam coverage range are obtained according to the ground beam coverage range;

[0048] The carrier's 3D velocity error and height error are added to the ground beam coverage to obtain the actual ground beam coverage and the actual 2D positions of the four edge points of the actual beam coverage.

[0049] The difference between the actual two-dimensional position and the theoretical two-dimensional position is calculated, and the maximum value of the ratio of the difference to the two-dimensional width of the actual beam coverage range is the distortion rate.

[0050] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0051] 1. The multi-dimensional visualization analysis method for SAR detection capability provided by this invention comprehensively calculates and screens indicators such as range resolution, azimuth resolution, and ground reflectivity, which were previously calculated separately, to meet the needs of SAR detection capability analysis. It presents the radar capability boundary in multiple dimensions through two-dimensional images, maps the position, three-dimensional velocity, and three-dimensional attitude of the carrier to multiple dimensions such as the SAR's effective range, squinting angle, and off-axis angle. It presents the distribution characteristics of the resolution within the ground beam coverage area, realizes the detailed visualization of the coupling relationship between various SAR detection parameters and the detection boundary, and provides systematic support for radar solution design.

[0052] 2. The multi-dimensional visualization analysis method for SAR detection capability provided by the present invention can obtain the coupling of various SAR detection parameters and the capability boundary, meet the requirements of high-precision SAR detection, realize the refined analysis of SAR detection parameters, adapt to multi-task requirements, and facilitate SAR solution design decisions.

[0053] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0055] Figure 1 A schematic diagram of the connection between the memory and the housing in the multi-dimensional visual analysis system for SAR detection capabilities provided in the second embodiment of the present invention;

[0056] Figure 2 This is a schematic diagram of the connection between the first arc rod and the connecting rod in the multi-dimensional visual analysis system for SAR detection capabilities provided in the second embodiment of the present invention.

[0057] Reference numerals:

[0058] 1-housing; 2-memory; 3-first arc-shaped rod; 4-second arc-shaped rod; 5-connecting tube; 6-outer ring; 7-first inner ring; 8-second inner ring; 9-baffle. DETAILED DESCRIPTION

[0059] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0060] Example 1

[0061] This embodiment provides a multi-dimensional visualization analysis method for SAR detection capability, including the following steps:

[0062] Step 1: Determine the ground beam coverage using the vehicle's flight parameters and the SAR's antenna installation angle and scanning range. Draw a grid within the beam coverage to obtain the grid point coordinate matrix within the beam coverage.

[0063] Step 2: Calculate the slant angle matrix and slant range matrix corresponding to the grid points within the beam coverage range based on the flight parameters of the carrier and the grid point coordinate matrix;

[0064] Step 3: Calculate the actual transmit gain matrix from the antenna to the grid point and the actual receive gain matrix from the antenna to the grid point based on the off-axis angle. It should be noted that the off-axis angle refers to the angle between the carrier target pointing and the antenna pointing;

[0065] Step 4: Calculate the SAR equation based on the actual transmit gain matrix from the antenna to the grid point, the actual receive gain matrix from the antenna to the grid point, the slant angle matrix, the slant range matrix, the SAR system loss (it should be noted that the SAR system loss is a fixed value. Each SAR model has a fixed system loss, usually including waveform loss or transmission loss, etc.), and the average power to obtain the ground reflection coefficient matrix of the grid point at different range resolutions.

[0066] According to the bandwidth of SAR, the height of the carrier and the slant range matrix, the range resolution matrix of the grid points is obtained;

[0067] The azimuth resolution matrix of the grid points is obtained according to the carrier's velocity (which can be obtained by calculating the carrier's three-dimensional velocity), wavelength, synthetic aperture time, slant angle matrix and slant range matrix;

[0068] According to the threshold range, the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix are screened to obtain multiple grid points that simultaneously meet the distance resolution, azimuth resolution, and ground reflection coefficient. These are graphically displayed to obtain a two-dimensional analysis diagram.

[0069] Illustratively, in the above steps 1 and 2, the flight parameters of the carrier include the coordinates, pitch attitude, yaw attitude, roll attitude and three-dimensional velocity of the carrier in the navigation coordinate system.

[0070] It should be noted that the carrier refers to a substrate for carrying the SAR, for example, an aircraft or other aircraft.

[0071] According to the two-dimensional analysis diagram obtained according to the above steps, the beam coverage range can be divided into multiple areas, and the resolution distribution characteristics within the ground beam coverage range at different oblique angles can be obtained, for example, resolving 1 meter × 1 meter × sigma (ground reflection coefficient) = -12, 3 meters × 3 meters × sigma (ground reflection coefficient) = -12 and 5 meters × 5 meters × sigma (ground reflection coefficient) = -12. In practical applications, for example, the grid points of the circular marks are grid points that meet the distance resolution and azimuth resolution of 1 meter × 1 meter × sigma (ground reflection coefficient) = -12, the grid points of the cross-shaped marks are grid points that meet the distance resolution and azimuth resolution of 3 meters × 3 meters × sigma (ground reflection coefficient) = -12, and the grid points of the triangular marks are grid points that meet the distance resolution and azimuth resolution of 5 meters × 5 meters × sigma (ground reflection coefficient) = -12. When the carrier needs to perform image detection with a distance resolution and azimuth resolution of 1 meter × 1 meter × sigma (ground reflection coefficient) = -12, the various parameters of the carrier and the radar can be controlled to be consistent with the various parameters corresponding to the grid points of the circular marks, so that image detection with a distance resolution and azimuth resolution of 1 meter × 1 meter × sigma (ground reflection coefficient) = -12 can be achieved, thereby guiding radar image detection.

[0072] Compared with the existing technology, the multi-dimensional visualization analysis method for SAR detection capability provided in this embodiment comprehensively calculates and filters indicators such as range resolution, azimuth resolution, and ground reflection coefficient, which were previously calculated separately, to meet the needs of SAR detection capability analysis. It presents the radar capability boundary in multiple dimensions through two-dimensional images, maps the position, three-dimensional velocity, and three-dimensional attitude of the carrier to multiple dimensions such as the SAR's effective range, slant angle, and off-axis angle, and presents the distribution characteristics of the resolution within the ground beam coverage range. This realizes a detailed visualization of the coupling relationship between various SAR detection parameters and the detection boundary, providing systematic support for radar solution design.

[0073] Specifically, in step 1 above, the following method is used to obtain the grid point coordinate matrix within the beam coverage range:

[0074] T x =[x1, x2, ..., x M ]

[0075] T z =[z1,z2,…,z N ]

[0076] Among them, x1, x M 、z1、z N are the coordinates of the intersection of the maximum coverage range of the beam and the two-dimensional coordinate axis of the ground, T x 、T zis the two-dimensional coordinate matrix of the grid points, x is an integer from 1 to M, and z is an integer from 1 to N.

[0077] In step 2 above, the slant angle matrix θ and slant range matrix R corresponding to the grid points within the beam coverage range are calculated based on the flight parameters of the carrier and the grid point coordinate matrix using the following formula:

[0078] θ v =arctan(v z / v x )

[0079] θ p =arctan(T z -P z ) / (T x -P z )

[0080] θ=θ p -θ v

[0081]

[0082] Among them, θ is the slant angle matrix, R is the slant distance matrix, and v x is the north velocity of the carrier in the navigation coordinate system, v z is the east speed of the carrier in the navigation coordinate system, (P x , P y , P z ) is the coordinate of the carrier in the navigation coordinate system, T x 、T z is the two-dimensional coordinate matrix of the grid points, x is an integer from 1 to M, and z is an integer from 1 to N.

[0083] In the above step 3, according to the off-axis angle matrix Calculate the actual transmission gain matrix G from the antenna to the grid point tT And the actual receiving gain matrix G from the antenna to the grid point rT Use the following formula:

[0084]

[0085]

[0086] Among them, G t is the antenna transmission gain, G r G is the antenna receiving gain. Each model of GAR has a fixed G t and G r , both are known values, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, is the off-axis angle matrix.

[0087] In step 4 above, the SAR equation is calculated based on the actual transmission gain matrix from the antenna to the grid point, the actual receiving gain matrix from the antenna to the grid point, the slant angle matrix, the slant range matrix, the SAR system loss and the average power. The ground reflection coefficient matrix of the grid point at different resolutions is obtained using the following formula:

[0088]

[0089] Where σ is the ground reflection coefficient matrix, R is the slant range matrix, K = 1.38 × 10 -23 is the Boltzmann constant, T0 is the noise temperature, F n is the noise coefficient, L is the system loss, v is the sum velocity of the carrier in the north-east plane in the navigation coordinate system, θ is the oblique viewing angle matrix, P av is the average power, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, SNR is the detection signal-to-noise ratio, λ is the wavelength, D r is the range resolution (in this formula, is the specified value), and k=1.4 is the azimuth broadening factor.

[0090] In the above step 4, according to the bandwidth B of SAR r , the height of the carrier, the slant distance R matrix to calculate the distance resolution matrix D r Use the following formula:

[0091]

[0092]

[0093] Among them, D r is the distance resolution matrix, R is the slant range matrix, B r is the bandwidth of SAR, (P x ,P y ,P z ) is the coordinate of the carrier in the navigation coordinate system, k is the azimuth broadening factor, c is the speed of light, and β is the ground-grabbing angle.

[0094] The azimuth resolution matrix D is calculated based on the carrier's velocity, wavelength, synthetic aperture time, slant angle matrix and slant range matrix. a Use the following formula:

[0095]

[0096] Among them, D ais the azimuth resolution matrix, k is the azimuth broadening factor, λ is the wavelength, R is the slant range matrix, v is the sum velocity of the carrier in the northeast plane in the navigation coordinate system, θ is the slant angle matrix, T a is the synthetic aperture time.

[0097] Exemplarily, screening the distance resolution in the distance resolution matrix, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix of the grid points according to the threshold range includes the following steps:

[0098] Step a: Determine whether the range resolution in the range resolution matrix is ​​within the range resolution threshold range. If so, determine whether the grid point corresponding to the range resolution meets the conditions, and obtain multiple grid points that meet the range resolution.

[0099] Step b: determining whether the azimuth resolution of the plurality of grid points satisfying the range resolution is within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the condition, and obtaining a plurality of grid points satisfying both the range resolution and the azimuth resolution;

[0100] Step c: Determine whether the ground reflection coefficients of multiple grid points that simultaneously meet the distance resolution and azimuth resolution are within the ground reflection coefficient threshold range. If so, determine whether the grid points corresponding to the ground reflection coefficients meet the conditions, and obtain multiple grid points that simultaneously meet the distance resolution, azimuth resolution, and ground reflection coefficient.

[0101] Alternatively, screening the range resolution in the range resolution matrix, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix of the grid points according to the threshold range includes the following steps:

[0102] Step a': determining whether the azimuth resolution in the azimuth resolution matrix is ​​within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the conditions, and obtaining a plurality of grid points that meet the azimuth resolution;

[0103] Step b': determining whether the range resolution of the plurality of grid points satisfying the azimuth resolution is within a range of the range resolution threshold; if so, determining whether the grid points corresponding to the range resolution satisfy the conditions, and obtaining a plurality of grid points satisfying both the azimuth resolution and the range resolution;

[0104] Step c': Determine whether the ground reflection coefficients of multiple grid points that simultaneously meet the azimuth resolution and the range resolution are within the ground reflection coefficient threshold range. If so, determine whether the grid points corresponding to the ground reflection coefficients meet the conditions, and obtain multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient.

[0105] Alternatively, screening the range resolution in the range resolution matrix, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix of the grid points according to the threshold range includes the following steps:

[0106] Step a'': determining whether a ground reflection coefficient in a ground reflection coefficient matrix is ​​within a ground reflection coefficient threshold range; if so, determining whether a grid point corresponding to the ground reflection coefficient satisfies a condition, and obtaining a plurality of grid points satisfying the ground reflection coefficient;

[0107] Step b'': determining whether the azimuth resolution of the plurality of grid points satisfying the ground reflection coefficient is within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the condition, and obtaining a plurality of grid points satisfying both the ground reflection coefficient and the azimuth resolution;

[0108] Step c”: Determine whether the range resolution of the multiple grid points that simultaneously meet the ground reflection coefficient and azimuth resolution is within the range resolution threshold. If so, determine whether the grid points corresponding to the range resolution meet the conditions, and obtain multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient.

[0109] Alternatively, screening the range resolution in the range resolution matrix, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix of the grid points according to the threshold range includes the following steps:

[0110] Step A: Determine whether the ground reflection coefficient in the ground reflection coefficient matrix is ​​within the ground reflection coefficient threshold range. If so, determine whether the grid point corresponding to the ground reflection coefficient meets the conditions, and obtain multiple grid points that meet the ground reflection coefficient.

[0111] Step B: Determine whether the range resolution of the multiple grid points that meet the ground reflection coefficient is within the range of the range resolution threshold. If so, determine whether the grid points corresponding to the range resolution meet the conditions, and obtain multiple grid points that simultaneously meet the ground reflection coefficient and the range resolution.

[0112] Step C: Determine whether the azimuth resolution of multiple grid points that simultaneously meet the ground reflection coefficient and distance resolution is within the azimuth resolution threshold range. If so, determine whether the grid point corresponding to the azimuth resolution meets the conditions, and obtain multiple grid points that simultaneously meet the distance resolution, azimuth resolution, and ground reflection coefficient.

[0113] Alternatively, screening the range resolution in the range resolution matrix, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix of the grid points according to the threshold range includes the following steps:

[0114] Step A': determining whether the azimuth resolution in the azimuth resolution matrix is ​​within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the conditions, and obtaining a plurality of grid points that meet the azimuth resolution;

[0115] Step B': determining whether the range resolution of the multiple grid points that meet the azimuth resolution is within the ground reflection coefficient threshold range; if so, determining whether the grid point corresponding to the ground reflection coefficient meets the condition, and obtaining multiple grid points that simultaneously meet the azimuth resolution and the ground reflection coefficient;

[0116] Step C': Determine whether the range resolution of multiple grid points that simultaneously meet the requirements of azimuth resolution and ground reflection coefficient is within the range resolution threshold. If so, determine whether the grid points corresponding to the range resolution meet the requirements, and obtain multiple grid points that simultaneously meet the requirements of range resolution, azimuth resolution, and ground reflection coefficient.

[0117] Alternatively, screening the range resolution in the range resolution matrix, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix of the grid points according to the threshold range includes the following steps:

[0118] Step A”: determining whether the range resolution in the range resolution matrix is ​​within a range resolution threshold range; if so, determining whether the grid point corresponding to the range resolution satisfies a condition, and obtaining a plurality of grid points that satisfy the range resolution;

[0119] Step B': determining whether the azimuth resolution of the plurality of grid points that meet the range resolution is within a ground reflection coefficient threshold range; if so, determining whether the grid point corresponding to the ground reflection coefficient meets the condition, and obtaining a plurality of grid points that simultaneously meet the range resolution and the ground reflection coefficient;

[0120] Step C”: Determine whether the azimuth resolution of multiple grid points that simultaneously meet the range resolution and the ground reflection coefficient is within the azimuth resolution threshold range. If so, determine whether the grid point corresponding to the azimuth resolution meets the conditions, and obtain multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient.

[0121] Alternatively, screening the range resolution in the range resolution matrix, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix of the grid points according to the threshold range includes the following steps:

[0122] At the same time, it is determined whether the distance resolution in the distance resolution matrix is ​​within the distance resolution threshold range, whether the azimuth resolution in the azimuth resolution matrix is ​​within the azimuth resolution threshold range, and whether the ground reflection coefficient in the ground reflection coefficient matrix is ​​within the ground reflection coefficient threshold range;

[0123] If the range resolution, azimuth resolution, and ground reflection coefficient are all within their respective threshold ranges, the grid points corresponding to the range resolution, azimuth resolution, and ground reflection coefficient are judged to meet the conditions, and multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient are obtained.

[0124] It is worth noting that in actual applications, the speed error and altitude error of the carrier will also affect the detection capability of SAR. Therefore, the above step 4 also includes the following steps:

[0125] Calculate the distortion rate based on the velocity error and height error of the carrier;

[0126] According to the threshold range, multiple grid points that simultaneously meet the range resolution, azimuth resolution and ground reflection coefficient are subjected to distortion screening, and the grid points after distortion screening are graphically displayed as grid points that meet the conditions.

[0127] Specifically, the calculation of the distortion rate based on the velocity error and height error of the carrier includes the following steps:

[0128] The theoretical two-dimensional positions of the four edge points of the ground beam coverage range are obtained according to the ground beam coverage range;

[0129] The carrier's 3D velocity error and height error are added to the ground beam coverage to obtain the actual ground beam coverage and the actual 2D positions of the four edge points of the actual beam coverage.

[0130] The difference between the actual two-dimensional position and the theoretical two-dimensional position is calculated, and the maximum value of the ratio of the difference to the two-dimensional width of the actual beam coverage range is the distortion rate.

[0131] Example 2

[0132] This embodiment provides a multi-dimensional visualization analysis system for SAR detection capability, including a grid point coordinate matrix acquisition unit, a slant angle matrix and slant range matrix acquisition unit, an antenna-to-grid point actual transmission gain matrix and an antenna-to-grid point actual reception gain matrix acquisition unit, a range resolution acquisition unit, an azimuth resolution acquisition unit, a ground reflection coefficient acquisition unit, a threshold comparison unit, and a graphical display unit.

[0133] The grid point coordinate matrix acquisition unit determines the ground beam coverage range using the flight parameters of the carrier and the antenna installation angle and scanning range of the SAR, draws a grid within the beam coverage range, and obtains the grid point coordinate matrix within the beam coverage range;

[0134] The slant angle matrix and slant range matrix acquisition unit is used to calculate the slant angle matrix and slant range matrix corresponding to the grid points within the beam coverage range according to the flight parameters of the carrier and the grid point coordinate matrix;

[0135] The actual transmission gain matrix from the antenna to the grid point and the actual reception gain matrix from the antenna to the grid point are obtained by the unit for calculating the actual transmission gain matrix from the antenna to the grid point and the actual reception gain matrix from the antenna to the grid point according to the off-axis angle;

[0136] The ground reflection coefficient matrix acquisition unit receives the actual transmission gain matrix from the antenna to the grid point, the actual receiving gain matrix from the antenna to the grid point, the slant angle matrix, and the slant range matrix, and calculates the SAR equation based on the actual transmission gain matrix from the antenna to the grid point, the actual receiving gain matrix from the antenna to the grid point, the slant angle matrix, the slant range matrix, the system loss and the average power of the SAR to obtain the ground reflection coefficient matrix of the grid point at different distance resolutions;

[0137] The range resolution acquisition unit receives the slant range matrix and obtains the range resolution matrix of the grid points based on the bandwidth of the SAR, the height of the carrier and the slant range matrix;

[0138] The azimuth resolution acquisition unit receives the slant angle matrix and the slant range matrix, and obtains the azimuth resolution matrix of the grid points according to the carrier's velocity, wavelength, synthetic aperture time, slant angle matrix and slant range matrix;

[0139] The threshold comparison unit receives the distance resolution matrix, the azimuth resolution matrix and the ground reflection coefficient matrix respectively, and compares them with the threshold range stored in the threshold comparison unit to obtain multiple grid points that simultaneously meet the distance resolution, azimuth resolution and ground reflection coefficient and send them to the graphical display unit to display a two-dimensional analysis diagram.

[0140] Compared with the prior art, the beneficial effects of the SAR detection capability multi-dimensional visualization analysis system provided in this embodiment are substantially the same as the beneficial effects of the SAR detection capability multi-dimensional visualization analysis method provided in Example 1, and are not described in detail here.

[0141] Specifically, in the above-mentioned grid point coordinate matrix acquisition unit, the grid point coordinate matrix adopts the following formula:

[0142] T x =[x1, x2, ..., x M ]

[0143] Tz =[z1,z2,…,z N ]

[0144] Among them, x1, x M 、z1、z N are the coordinates of the intersection of the maximum coverage range of the beam and the two-dimensional coordinate axis of the ground, T x 、T z is the two-dimensional coordinate matrix of the grid points.

[0145] In the above-mentioned slant angle matrix and slant distance matrix acquisition unit, the slant angle matrix θ and the slant distance matrix R are calculated using the following formula:

[0146] θ v =arctan(v z / v x )

[0147] θ p =arctan(T z -P z ) / (T x -P z )

[0148] θ=θ p -θ v

[0149]

[0150] Among them, θ is the slant angle matrix, R is the slant distance matrix, and v x is the north velocity of the carrier in the navigation coordinate system, v z is the east speed of the carrier in the navigation coordinate system, (P x , P y , P z ) is the coordinate of the carrier in the navigation coordinate system, T x 、T z is the two-dimensional coordinate matrix of the grid points.

[0151] In the above-mentioned actual transmission gain matrix from antenna to grid point and actual receiving gain matrix from antenna to grid point obtaining unit, the actual transmission gain matrix from antenna to grid point G tT And the actual receiving gain matrix G from the antenna to the grid point rT The calculation is based on the following formula:

[0152]

[0153]

[0154] Among them, G t is the antenna transmission gain, G rG is the antenna receiving gain. Each model of GAR has a fixed G t and G r , both are known values, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, is the off-axis angle matrix.

[0155] In the above ground reflection coefficient matrix acquisition unit, the ground reflection coefficient matrix is ​​calculated using the following formula:

[0156]

[0157] Where σ is the ground reflection coefficient matrix, R is the slant range matrix, K = 1.38 × 10 -23 is the Boltzmann constant, T0 is the noise temperature, F n is the noise coefficient, L is the system loss, v is the sum velocity of the carrier in the north-east plane in the navigation coordinate system, θ is the oblique viewing angle matrix, P av is the average power, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, SNR is the detection signal-to-noise ratio, λ is the wavelength, D r is the range resolution (in this formula, is the specified value), and k=1.4 is the azimuth broadening factor.

[0158] In the above distance resolution acquisition unit, the distance resolution matrix D r The calculation is based on the following formula:

[0159]

[0160]

[0161] Among them, D r is the distance resolution matrix, R is the slant range matrix, B r is the bandwidth of SAR, (P x , P y , P z ) is the coordinate of the carrier in the navigation coordinate system, k is the azimuth broadening factor, c is the speed of light, and β is the ground-grabbing angle.

[0162] In the above-mentioned azimuth resolution acquisition unit, the azimuth resolution matrix D a The calculation is based on the following formula:

[0163]

[0164] Among them, D ais the azimuth resolution matrix, k is the azimuth broadening factor, λ is the wavelength, R is the slant range matrix, v is the sum velocity of the carrier in the northeast plane in the navigation coordinate system, θ is the slant angle matrix, T a is the synthetic aperture time.

[0165] It is worth noting that, in practical applications, the velocity error and height error of the carrier will also affect the detection capability of SAR. Therefore, the multi-dimensional visualization analysis system for SAR detection capability also includes a distortion rate acquisition unit;

[0166] The threshold comparison unit receives the distortion rate and compares the distortion rates corresponding to multiple grid points that simultaneously meet the distance resolution, azimuth resolution and ground reflection coefficient with the threshold stored in the threshold comparison unit, obtains multiple grid points that simultaneously meet the distance resolution, azimuth resolution, ground reflection coefficient and distortion rate and sends them to the graphical display unit to display a two-dimensional analysis graph.

[0167] It can be understood that in order to realize the storage of the above-mentioned units, the above-mentioned SAR detection capability multi-dimensional visualization analysis system also includes a memory 2 for storing a grid point coordinate matrix acquisition unit, a slant angle matrix and a slant range matrix acquisition unit, an antenna to grid point actual transmission gain matrix and an antenna to grid point actual receiving gain matrix acquisition unit, a distance resolution acquisition unit, an azimuth resolution acquisition unit, a ground reflection coefficient acquisition unit, a threshold comparison unit and a graphical display unit. Exemplarily, the memory 2 can be a chip.

[0168] In order to effectively protect the memory 2, the above-mentioned SAR detection capability multi-dimensional visualization analysis system also includes a shell 1. The memory 2 is arranged in the shell 1. The shell 1 can effectively protect the memory 2 and extend its service life.

[0169] In practical applications, considering that the memory 2 is an electronic device, when the carrier is an aircraft, the memory 2 will inevitably be subjected to a certain impact when the carrier lands. The above-mentioned SAR detection capability multi-dimensional visualization analysis system also includes a buffer, and the memory 2 is detachably connected to the housing 1 through the buffer. Figure 1 .

[0170] By way of example, the buffer member comprises a first curved rod 3, a connecting tube 5, and a second curved rod 4. One end of the first curved rod 3 is slidably connected to one end of the second curved rod 4 via the connecting tube 5. The other ends of the first curved rod 3 and the second curved rod 4 are connected to the housing 1, and the reservoir 2 is disposed on the connecting tube 5. Thus, on the one hand, because both the first curved rod 3 and the second curved rod 4 are curved, when the reservoir 2 is impacted, the first curved rod 3 and the second curved rod 4 can undergo a certain degree of elastic deformation, thereby providing a buffering effect. On the other hand, one end of the first curved rod 3 is slidably connected to one end of the second curved rod 4 via the connecting tube 5. During the elastic deformation of the first curved rod 3 and the second curved rod 4, the ends of the two rods approach each other, increasing their elastic deformation and thus further buffering the impact.

[0171] Considering that any material has a deformation limit, in order to avoid the first curved rod 3 and the second curved rod 4 from being damaged due to excessive deformation, it is necessary to appropriately limit the relative sliding displacement between the first curved rod 3 and the second curved rod 4. One end of the connecting tube 5 is sleeved on the outer wall of the first curved rod 3, and the other end of the connecting tube 5 is sleeved on the outer wall of the second curved tube. Limiting members are provided between the connecting tube 5 and the first curved rod 3 and between the connecting tube 5 and the second curved rod 4. Figure 2 .

[0172] Exemplarily, the limiting member includes an outer ring 6 provided on the outer walls of the first arc rod 3 and the second arc rod 4 and an inner ring provided on the inner wall of the connecting tube 5. The outer ring 6 is a rigid ring and the inner ring is an elastic ring. The inner diameter of the inner ring is smaller than the outer diameter of the outer ring 6. As the inner diameters of the multiple inner rings gradually decrease as they approach the midpoint of the connecting tube 5.

[0173] Taking the inner ring and outer ring 6 between the connecting tube 5 and the first arc rod 3 as an example, the number of outer ring 6 is 1, and the number of inner rings is 2, namely the first inner ring 7 and the second inner ring 8. A baffle 9 is provided on the side of the second inner ring 8 away from the first inner ring 7. When not impacted, the outer ring 6 is located on the side of the first inner ring 7 away from the second inner ring 8 and does not contact the first inner ring 7; when the elastic deformation of the first arc rod 3 is too large, the outer ring 6 squeezes the first inner ring 7 and enters between the first inner ring 7 and the second inner ring 8, and collides with the second inner ring 8, absorbing part of the impact force, and the second inner ring 8 can limit the sliding displacement between the first arc member and the connecting tube 5 to a certain extent, preventing the outer ring 6 from further sliding displacement; when the first arc rod 3 is close to the maximum elastic deformation, the outer ring 6 squeezes the second inner ring 8 and abuts against the baffle 9, thereby preventing the outer ring 6 from further sliding displacement, thereby avoiding damage to the outer ring 6.

[0174] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A multi-dimensional visualization analysis method for SAR detection capability, characterized in that: The steps include: Step 1: Determine the ground beam coverage using the vehicle's flight parameters and the SAR's antenna installation angle and scanning range. Draw a grid within the beam coverage to obtain the grid point coordinate matrix within the beam coverage. Step 2: Calculate the slant angle matrix and slant range matrix corresponding to the grid points within the beam coverage range based on the flight parameters of the carrier and the grid point coordinate matrix using the following formula: θ v =arctan(v z / v x ) θ=θ p -θ v Step 3: Calculate the actual transmit gain matrix from the antenna to the grid point and the actual receive gain matrix from the antenna to the grid point based on the off-axis angle; Step 4: Calculate the SAR equation based on the actual transmission gain matrix from the antenna to the grid point, the actual receiving gain matrix from the antenna to the grid point, the slant angle matrix, the slant range matrix, the SAR system loss, and the average power. The ground reflection coefficient matrix at different distance resolutions of the grid point is obtained using the following formula: According to the bandwidth of SAR, the height of the carrier and the slant range matrix, the range resolution matrix of the grid points is obtained using the following formula: According to the carrier's velocity, wavelength, synthetic aperture time, slant angle matrix and slant range matrix, the azimuth resolution matrix of the grid points is obtained using the following formula: The distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix are screened according to the threshold range to obtain multiple grid points that simultaneously meet the distance resolution, azimuth resolution, and ground reflection coefficient, and display them graphically to obtain a two-dimensional analysis diagram; Step 5: Analyze SAR detection capability based on the obtained two-dimensional analysis graph; In the above formula, θ is the slant angle matrix, R is the slant distance matrix, and v x is the north velocity of the carrier in the navigation coordinate system, v z is the east speed of the carrier in the navigation coordinate system, (P x ,P y ,P z ) is the coordinate of the carrier in the navigation coordinate system, T x 、T z is the two-dimensional coordinate matrix of the grid points, x is an integer from 1 to M, z is an integer from 1 to N, σ is the ground reflection coefficient matrix, K = 1.38 × 10 -23 is the Boltzmann constant, T0 is the noise temperature, F n is the noise coefficient, L is the system loss, v is the velocity of the carrier in the northeast plane in the navigation coordinate system, P av is the average power, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, SNR is the detection signal-to-noise ratio, λ is the wavelength, D r is the range resolution, k=1.4 is the azimuth broadening factor, B r is the bandwidth of SAR, c is the speed of light, β is the grazing angle, D a is the azimuth resolution matrix, T a is the synthetic aperture time.

2. The multidimensional visualization analysis method for SAR detection capability according to claim 1, characterized in that: In step 1, the following method is used to obtain the grid point coordinate matrix within the beam coverage range: T x =[x1,x2,…,x M ] T z =[z1,z2,…,z N ] Among them, x1, x M 、z1、z N They are the coordinates of the intersection of the maximum coverage range of the beam and the two-dimensional coordinate axis of the ground.

3. The multidimensional visualization analysis method for SAR detection capability according to claim 1, characterized in that: In step 3, according to the off-axis angle matrix (Calculate the actual transmission gain matrix G from the antenna to the grid point tT And the actual receiving gain matrix G from the antenna to the grid point rT Use the following formula: Among them, G t is the antenna transmission gain, G r is the antenna receiving gain, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, is the off-axis angle matrix.

4. The multidimensional visualization analysis method for SAR detection capability according to any one of claims 1 to 3, characterized in that: In step 4, screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range includes the following steps: At the same time, it is determined whether the distance resolution in the distance resolution matrix is ​​within the distance resolution threshold range, whether the azimuth resolution in the azimuth resolution matrix is ​​within the azimuth resolution threshold range, and whether the ground reflection coefficient in the ground reflection coefficient matrix is ​​within the ground reflection coefficient threshold range; If the range resolution, azimuth resolution, and ground reflection coefficient are all within their respective threshold ranges, the grid points corresponding to the range resolution, azimuth resolution, and ground reflection coefficient are judged to meet the conditions, and multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient are obtained.

5. The multi-dimensional visualization analysis method for SAR detection capability according to any one of claims 1 to 3, characterized in that: The step 4 also includes the following steps: Calculate the distortion rate based on the velocity error and height error of the carrier; According to the threshold range, multiple grid points that simultaneously meet the range resolution, azimuth resolution and ground reflection coefficient are subjected to distortion screening, and the grid points after distortion screening are graphically displayed as grid points that meet the conditions.

6. The multi-dimensional visualization analysis method of SAR detection capability according to claim 5, characterized in that: Calculating the distortion rate based on the velocity error and height error of the carrier includes the following steps: The theoretical two-dimensional positions of the four edge points of the ground beam coverage range are obtained according to the ground beam coverage range; The carrier's 3D velocity error and height error are added to the ground beam coverage to obtain the actual ground beam coverage and the actual 2D positions of the four edge points of the actual beam coverage. The difference between the actual two-dimensional position and the theoretical two-dimensional position is calculated, and the maximum value of the ratio of the difference to the two-dimensional width of the actual beam coverage range is the distortion rate.

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