A one-dimensional angular positioning method for SAR moving targets with known target height

Abstract

The present invention discloses a one-dimensional angular positioning method for a SAR moving target with a known target height, belonging to the technical field of SAR radar signal processing. The present invention is implemented based on complex image data of two SAR channels, namely, a sum channel and an azimuth difference channel. Compared with a two-dimensional angular positioning method based on complex image data of three channels, namely, a sum channel, an azimuth difference channel, and an elevation difference channel, the present invention has lower requirements for system hardware, requiring only subarray division and beam synthesis in one dimension, namely, azimuth. In contrast, two-dimensional angular measurement requires subarray division and beam synthesis in both azimuth and elevation. Furthermore, the present invention has lower requirements for SAR imaging processing and data storage capabilities. Compared with a two-dimensional angular positioning method, the one-dimensional angular positioning method reduces the SAR imaging processing and data storage capacity by 1 / 3. Furthermore, the implementation process is simple and easy.

Description

Technical Field

[0001] The present invention relates to the technical field of SAR radar signal processing, and in particular to a one-dimensional angle measurement and positioning method for a SAR moving target with a known target height. Background Art

[0002] Synthetic Aperture Radar (SAR) is widely used in military reconnaissance and guidance due to its long-range, high-resolution, and all-weather capabilities. The three-dimensional spatial position information of the target of interest in SAR images is a key parameter in SAR image applications.

[0003] For stationary targets, target position information can be calculated using the range-Doppler value and the spatial geometric relationship between the radar platform and the target. For moving targets, the target velocity causes an additional Doppler shift, and since the target velocity is unknown, using stationary target positioning methods to locate moving targets can result in significant positioning errors. Therefore, sum-and-difference angle measurement can be used to measure and locate moving targets.

[0004] Traditional sum-difference angular positioning methods achieve three-dimensional target positioning through two-dimensional angular measurement results in azimuth and elevation, target slant range, and coordinate conversion. However, two-dimensional angular positioning methods place high demands on the hardware system, requiring the system to perform subarray division and beamforming in both azimuth and elevation, and signal processing to complete SAR imaging of at least three channels of data. Considering that platform and target altitude information is not used in the two-dimensional angular positioning process, and in some cases, target altitude information is easier to obtain, a one-dimensional angular positioning method for SAR moving targets with known target altitude is proposed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to realize one-dimensional angular positioning of SAR moving targets when the target height is known. A one-dimensional angular positioning method for SAR moving targets when the target height is known is provided. The method is based on the range Doppler complex data of two channels, the SAR image and the channel and the azimuth difference channel, and completes the three-dimensional spatial positioning of the target through amplitude angle measurement, coordinate transformation and solving a group of equations.

[0006] The present invention solves the above technical problems through the following technical solutions, which include the following steps:

[0007] S1: One-dimensional angle measurement of target pixel

[0008] Based on the sum-azimuth difference two-channel complex image data, the difference-sum amplitude ratio angle measurement method is used to complete the azimuth dimension angle measurement of the target pixel;

[0009] S2: Calculation of target z-coordinates under the antenna system

[0010] Calculate the target azimuth sight angle under the antenna system based on the antenna beam center pointing angle and the azimuth angle measurement result of step S1, and calculate the z-direction coordinate of the target under the antenna system through the target azimuth sight angle and the target slant range;

[0011] S3: Solve the target vector in the auxiliary system by listing the equations

[0012] The target vector coordinates in the auxiliary system are solved according to the z-coordinates of the target in the antenna system, the relative height between the platform and the target in the auxiliary system, the slant range of the target, and the coordinate transformation matrix from the auxiliary system to the antenna system.

[0013] S4: Validity judgment of target vector under auxiliary system

[0014] According to the target vector coordinates and coordinate conversion relationship in the auxiliary system, the target vector is converted to the antenna system and the target elevation line of sight angle deviation is calculated. The validity of the target vector coordinates is determined by whether the target elevation line of sight angle deviation is less than the half beam width.

[0015] S5: Calculation of target three-dimensional coordinates in the target system

[0016] When there is a valid target vector, the three-dimensional coordinates of the target in the target system are solved according to the target vector coordinates in the auxiliary system and the platform position in the target system.

[0017] Furthermore, in the steps S1 to S5, the antenna system is the antenna coordinate system, the target system is the target coordinate system, and the auxiliary system is the auxiliary coordinate system; wherein the antenna system takes the center of the antenna array as the origin o A , o A x A The direction of the normal to the antenna array is consistent, o A y A Pointing upward within the antenna array, o A -x A y A z A A right-hand rectangular coordinate system is formed, and the target system takes the specified point in the imaging area as the origin. T x T The axis points to the north in the imaging horizontal plane, o T y T The axis is perpendicular to the specified point, o T -x T y T z T is a right-hand rectangular coordinate system, and the auxiliary system is the translation of the target system. The origin of the target system is translated to the target height plane just below the platform at the moment of imaging. S x S The axis points north in the target altitude plane, o S y S The axis is perpendicular to the ground, o S-x S y S z S It is a right-handed rectangular coordinate system.

[0018] Furthermore, in step S1, the specific processing process is as follows:

[0019] S11: Calculate the amplitude and phase of the ratio of the azimuth difference channel to the sum channel of the complex image data of the pixel where the target is located. The complex data of the sum channel and the azimuth difference channel are in the following form:

[0020]

[0021] Among them, Σ, Σ I and Σ Q are the complex, real and imaginary parts of the channel pixels, Δ, Δ I and Δ Q are the complex number, real part and imaginary part of the difference channel pixel respectively, and j is the imaginary unit;

[0022] The difference and ratio are as follows:

[0023]

[0024] The magnitude and phase of the difference and ratio are:

[0025]

[0026] S12: Calculate the azimuth angle measurement value by looking up the table interpolation based on the difference and ratio amplitude and the measured amplitude-angle curve, and judge the polarity of the angle measurement value by the polarity of the difference and ratio phase to obtain the azimuth angle measurement result φ Az .

[0027] Furthermore, in step S2, the specific processing process is as follows:

[0028] S21: Calculate the antenna system beam center vector based on the antenna beam pointing angle as follows:

[0029]

[0030] Among them, A is the beam center vector of the antenna system, A x 、A y 、A z are the three-dimensional coordinates of vector A, α and β are the azimuth and elevation pointing angles of the antenna beam respectively;

[0031] S22: Calculate the antenna system beam center line of sight angle based on the geometric relationship as follows:

[0032]

[0033] in, and They are the azimuth and elevation line of sight angles of the beam center, and the geometric definitions of the azimuth and elevation line of sight angles are line of sight and o A -y A x A and o A -z A x A Angle;

[0034] S23: Calculate the target azimuth sight angle based on the target azimuth angle measurement result and the beam center sight angle

[0035]

[0036] S24: According to the target direction to the sight angle and target slope range R T Calculate the target under the antenna system z Towards coordinate A Tz :

[0037]

[0038] Furthermore, in step S3, the specific processing process is as follows:

[0039] S31: Calculate the coordinate transformation matrix M from the auxiliary system to the antenna system:

[0040]

[0041] Among them, M0~M8 are the elements of matrix M, M st and M at They are the antenna installation angle conversion matrix and the platform attitude angle conversion matrix respectively;

[0042] S32: Based on the conversion relationship from the auxiliary system to the antenna system, the target slant range, and the platform relative to the target height information in the target system, the conversion relationship from the auxiliary system to the antenna system is as follows:

[0043]

[0044] The system of equations is as follows:

[0045]

[0046] Among them, A T is the target vector under the antenna system, A Tx 、A Ty 、A Tz is vector A T The three-dimensional coordinates, S T is the target vector in the auxiliary frame, S Tx 、STy 、S Tz is the vector S T The three-dimensional coordinates of the target system, H is the relative height between the platform and the target; M6, M7, M8, A Tz 、R T , H are known quantities;

[0047] Then the system of equations is simplified to a system of two-variable quadratic equations as follows:

[0048]

[0049] S33: Solve the above quadratic equations to obtain the target vector coordinates 1 and 2 in the auxiliary system:

[0050]

[0051] in,

[0052] Furthermore, in step S4, the specific processing process is as follows:

[0053] S41: Calculate the target vector A in the antenna system according to the auxiliary system target vector coordinates obtained in step S3 and the conversion relationship from the auxiliary system to the antenna system. T_i =[A Tx_i A Ty_i A Tz_i ] T , i=1,2 correspond to target vector coordinate 1 and target vector coordinate 2 respectively;

[0054] S42: Calculate the elevation sight angle of the target under the antenna system according to the antenna system beam center sight angle formula

[0055]

[0056] S43: Compare the target pitching angle to the sight line with the beam center pitching angle to obtain the target pitching angle deviation

[0057]

[0058] S44: Determine the validity of the target vector based on the target elevation sight angle deviation: If the target is within the main lobe of the antenna beam, that is, the target elevation sight angle deviation is less than half the beam width, the target vector coordinates are determined to be valid; otherwise, they are invalid.

[0059] Furthermore, in step S44, the validity judgment expression is as follows:

[0060]

[0061] Among them, θ El is the antenna elevation beamwidth.

[0062] Furthermore, in step S5, the target three-dimensional coordinates are calculated using the formula:

[0063]

[0064] Among them, T x 、T y 、T z is the three-dimensional coordinate of the target in the target system, P x 、P y 、P z is the target system platform coordinate, that is, the target system platform position.

[0065] Compared with the existing technology, the present invention has the following advantages: the one-dimensional SAR moving target angle measurement and positioning method with known target height is implemented based on the complex image data of two channels, namely the SAR sum channel and the azimuth difference channel. Compared with the two-dimensional angular measurement and positioning method based on the complex image data of three channels, namely the sum channel, the azimuth difference channel and the elevation difference channel, the present invention has lower requirements on system hardware and only needs to perform sub-array division and beam synthesis in one dimension, namely the azimuth direction, while the two-dimensional angular measurement requires sub-array division and beam synthesis in both the azimuth and elevation directions, and has lower requirements on SAR imaging processing capability and data storage capability. Compared with the two-dimensional angular measurement and positioning method, the SAR imaging processing amount and data storage amount of the one-dimensional angular measurement and positioning method are reduced by 1 / 3; at the same time, the implementation process is simple and easy. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 1 is a flow chart of a method for one-dimensional angular positioning of a SAR moving target with a known target height in the first embodiment of the present invention;

[0067] Figure 2 Schematic diagram of the three-dimensional space coordinate system in the first embodiment of the present invention;

[0068] FIG3( a ) is a diagram showing the range Doppler imaging results of the neutralization channel in Example 2 of the present invention;

[0069] FIG3( b ) is a diagram of the range Doppler imaging result of the azimuth difference channel in Example 2 of the present invention;

[0070] FIG3( c ) is a diagram showing the range Doppler imaging result of the pitch difference channel in the second embodiment of the present invention;

[0071] Figure 4 This is a diagram showing the angle measurement error results in the second embodiment of the present invention;

[0072] Figure 5 This is a diagram showing the positioning error results in the second embodiment of the present invention. DETAILED DESCRIPTION

[0073] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process. However, the protection scope of the present invention is not limited to the following embodiment.

[0074] Example 1

[0075] This embodiment provides a technical solution: a SAR moving target one-dimensional angle measurement positioning method with a known target height, comprising the following steps:

[0076] (1) One-dimensional angle measurement of target pixel: Based on the sum-azimuth difference two-channel complex image data, the difference-sum amplitude ratio angle measurement method is used to complete the azimuth angle measurement of the target pixel;

[0077] (2) Calculation of the target's z-direction coordinate under the antenna system: Calculate the target's azimuth sight angle under the antenna system based on the antenna beam center pointing angle and the azimuth angle measurement result of step (1), and calculate the target's z-direction coordinate under the antenna system using the target's azimuth sight angle and the target's slant range;

[0078] (3) Solve the target vector in the auxiliary system by using a set of equations: The coordinates of the target vector in the auxiliary system are solved by using the set of equations based on the z-coordinates of the target in the antenna system, the relative height between the platform and the target in the auxiliary system, the slant range of the target, and the coordinate transformation matrix from the auxiliary system to the antenna system.

[0079] (4) Validity judgment of target vector in auxiliary system: Based on the target vector coordinates and coordinate conversion relationship in auxiliary system, the target vector is converted to antenna system and the target elevation line of sight angle deviation is calculated. The validity of the target vector coordinate is judged by whether the target elevation line of sight angle deviation is less than half beam width;

[0080] (5) Calculation of the three-dimensional coordinates of the target in the target system: When there is a valid target vector, the three-dimensional coordinates of the target in the target system are solved based on the target vector coordinates in the auxiliary system and the position of the target system platform.

[0081] like Figure 2 As shown in the figure, the three-dimensional space coordinate system involved in the above steps includes the antenna coordinate system, the target coordinate system and the auxiliary coordinate system, referred to as the antenna system, the target system and the auxiliary system. The antenna system takes the center of the antenna array as its origin. A , o A x A The direction of the normal to the antenna array is consistent, o A y A Pointing upward within the antenna array, o A -x A y A z A The target system takes the designated point in the imaging area as the origin,T x T The axis points to the north in the imaging horizontal plane, o T y T The axis is perpendicular to the specified point, o T -x T y T z T is a right-hand rectangular coordinate system. The auxiliary system is the translation of the target system, which translates the origin of the target system to the target height plane just below the platform at the moment of imaging. S x S The axis points north in the horizontal plane at the target altitude, o S y S The axis is perpendicular to the ground, o S -x S y S z S is a right-hand rectangular coordinate system. In the above steps: steps (1) and (2) are implemented in the antenna system; steps (3) and (4) are implemented using the conversion relationship between the antenna system and the auxiliary system to obtain the target vector in the auxiliary system; step (5) converts the target vector in the auxiliary system into coordinates in the target system for output.

[0082] like Figure 1 As shown, the step (1) specifically includes the following sub-steps:

[0083] (1a) Calculate the amplitude and phase of the ratio of the azimuth difference channel to the sum channel of the complex image data of the pixel where the target is located. The complex data of the sum channel and the azimuth difference channel are in the following form:

[0084]

[0085] Among them, Σ, Σ I and Σ Q are the complex, real and imaginary parts of the channel pixels, Δ, Δ I and Δ Q are the complex number, real part and imaginary part of the difference channel pixel respectively, and j is the imaginary unit;

[0086] The difference and ratio are as follows:

[0087]

[0088] The magnitude and phase of the difference and ratio are:

[0089]

[0090] (1b) The azimuth angle measurement value is calculated by looking up the table interpolation based on the difference and ratio amplitude and the measured amplitude-angle curve, and the polarity of the angle measurement value is determined by the polarity of the difference and ratio phase to obtain the azimuth angle measurement result φ Az .

[0091] like Figure 2 As shown, the specific process of step (2) is:

[0092] (2a) The antenna system beam center vector is calculated based on the antenna beam pointing angle as follows:

[0093]

[0094] Among them, A is the beam center vector of the antenna system, A x 、A y 、A z are the three-dimensional coordinates of vector A, α and β are the azimuth and elevation pointing angles of the antenna beam respectively, and the antenna rotation order is azimuth first and then elevation.

[0095] (2b) Based on the geometric relationship, the antenna system beam center line of sight angle is calculated as follows:

[0096]

[0097] in, and They are the azimuth and elevation line of sight angles of the beam center, and the geometric definitions of the azimuth and elevation line of sight angles are line of sight and o A -y A x A and o A -z A x A Angle;

[0098] (2c) Calculate the target azimuth sight angle based on the target azimuth angle measurement result and the beam center sight angle

[0099]

[0100] (2d) According to the target direction to the sight angle and target slope range R T Calculate the z-coordinate A of the target under the antenna system Tz :

[0101]

[0102] like Figure 2 As shown, the step (3) is specifically as follows:

[0103] (3a) Calculate the coordinate transformation matrix M from the auxiliary system to the antenna system:

[0104]

[0105] Among them, M0~M8 are the elements of matrix M, M st and Mat They are the antenna installation angle conversion matrix and the platform attitude angle conversion matrix respectively;

[0106] (3b) Based on the conversion relationship from the auxiliary system to the antenna system (Formula 3-2), the target slant range, and the platform relative target height information in the target system, the equation group (Formula 3-3) is established:

[0107]

[0108] Among them, A T is the target vector under the antenna system, A Tx 、A Ty 、A Tz is vector A T The three-dimensional coordinates, S T is the target vector in the auxiliary frame, S Tx 、S Ty 、S Tz is the vector S T The three-dimensional coordinates of the target system (also in the auxiliary system) are as follows: H is the relative height between the platform and the target; among them, M6, M7, M8, A Tz 、R T , H are known quantities, so the equations can be simplified to a quadratic equation as follows:

[0109]

[0110] (3c) Solve the quadratic equation system to obtain the target vector coordinates 1 and 2 in the auxiliary system:

[0111]

[0112] in, Since there are two sets of solutions to the quadratic equation system, the actual angle measurement and positioning only corresponds to one result, so the validity of the target vector needs to be judged through step (4).

[0113] like Figure 2 As shown, the specific process of step (4) is:

[0114] (4a) Calculate the target vector A in the antenna system by solving the target vector coordinates of the auxiliary system obtained in step (3) and (Formula 3-2) T_i =[A Tx_i A Ty_i A Tz_i ] T , i=1,2 correspond to target vector coordinate 1 and target vector coordinate 2 respectively;

[0115] (4b) Calculate the target elevation angle under the antenna system according to (Formula 2-2)

[0116]

[0117] (4c) Compare the target pitch-to-line-of-sight angle with the beam center pitch-to-line-of-sight angle to obtain the target pitch-to-line-of-sight angle deviation

[0118]

[0119] (4d) The target vector validity is determined based on the target elevation sight angle deviation: If the target is within the antenna beam main lobe, that is, the sight angle deviation is less than half the beam width, the target vector coordinates are considered valid; otherwise, they are invalid.

[0120]

[0121] Among them, θ El is the antenna elevation beamwidth.

[0122] When there is a valid target vector (ie the target vector coordinates are valid), the target coordinates are further calculated according to step (5).

[0123] like Figure 2 As shown, the specific process of step (5) is to calculate the target coordinates in the target system according to the target vector coordinates in the auxiliary system and the platform position in the target system:

[0124]

[0125] Among them, T x 、T y 、T z is the three-dimensional coordinate of the target in the target system, P x 、P y 、P z is the target system platform coordinate, that is, the target system platform position.

[0126] Example 2

[0127] Following the steps described in Example 1, a specific example was verified, using a point target to simulate a moving target for echo simulation and SAR imaging angular positioning. The simulation parameters were set as follows: radar wavelength 0.01713 m, slant range between platform and target 15 km to 9 km, relative altitude between platform and target 10 km to 6 km, and target velocity (0, 0, 10) m / s. The angular positioning results from 10 sets of data were statistically analyzed.

[0128] like Figure 3(a)-Figure 3(c)The figure shows a typical range Doppler distribution diagram in this embodiment. In the figure, the point target is a moving target. The target azimuth angle measurement result can be obtained by measuring the angle by comparing the azimuth difference channel and the sum channel complex image data, which is used in the subsequent positioning process of the present invention. In the same way, the target pitch angle measurement result can be obtained by measuring the angle by comparing the elevation difference channel and the sum channel complex image data. The combined azimuth angle measurement result can be used in the traditional two-dimensional angle measurement positioning process. The two-dimensional angle measurement results of the 10th set of data in Example 1 are shown in FIG. Figure 4 shown.

[0129] based on Figure 4 The azimuth angle measurement results of this embodiment are used for one-dimensional angle measurement positioning. For comparison, the traditional two-dimensional angle measurement positioning is performed based on the two-dimensional angle measurement results. At the same time, the range Doppler positioning is performed using the spatial geometric relationship. The spatial positioning errors of the three positioning methods are statistically analyzed as follows: Figure 5 As shown in the figure, the spatial angle measurement errors of one-dimensional and two-dimensional angle measurement positioning are basically the same, with mean errors of 10.83m and 10.15m, respectively. The spatial positioning error of the range Doppler positioning method varies from 320m to around 180m, with a mean of approximately 250m, which is much larger than the spatial positioning error of the angle measurement positioning method.

[0130] The range Doppler positioning method based on the range Doppler value of a stationary target and the spatial geometric relationship between the radar platform and the target is no longer applicable to moving targets. The positioning of moving targets needs to be achieved through angle measurement positioning methods. The one-dimensional angle measurement positioning method for SAR moving targets proposed in this invention, when the target height is known, has basically the same spatial positioning error as the two-dimensional angle measurement positioning method, but the method of the invention has lower requirements on system hardware and processing capabilities, and therefore has higher engineering application value.

[0131] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A SAR moving target one-dimensional angular positioning method with known target height, characterized in that: The following steps are involved: S1: One-dimensional angle measurement of target pixel Based on the sum-azimuth difference two-channel complex image data, the difference-sum amplitude ratio angle measurement method is used to complete the azimuth dimension angle measurement of the target pixel; S2: Calculation of target z-coordinates under the antenna system Calculate the target azimuth sight angle under the antenna system based on the antenna beam center pointing angle and the azimuth angle measurement result of step S1, and calculate the z-direction coordinate of the target under the antenna system through the target azimuth sight angle and the target slant range; S3: Solve the target vector in the auxiliary system by listing the equations The target vector coordinates in the auxiliary system are solved according to the z-coordinates of the target in the antenna system, the relative height between the platform and the target in the auxiliary system, the slant range of the target, and the coordinate transformation matrix from the auxiliary system to the antenna system. S4: Validity judgment of target vector under auxiliary system According to the target vector coordinates and coordinate conversion relationship in the auxiliary system, the target vector is converted to the antenna system and the target elevation line of sight angle deviation is calculated. The validity of the target vector coordinates is determined by whether the target elevation line of sight angle deviation is less than the half beam width. S5: Calculation of target three-dimensional coordinates in the target system When there is a valid target vector, the three-dimensional coordinates of the target in the target system are solved according to the target vector coordinates in the auxiliary system and the platform position in the target system.

2. The one-dimensional angular positioning method for a SAR moving target with a known target height according to claim 1, characterized in that: In the steps S1 to S5, the antenna system is the antenna coordinate system, the target system is the target coordinate system, and the auxiliary system is the auxiliary coordinate system; wherein the antenna system takes the center of the antenna array as the origin o A , o A x A The direction of the normal to the antenna array is consistent, o A y A Pointing upward within the antenna array, o A -x A y A z A A right-hand rectangular coordinate system is formed, and the target system takes the specified point in the imaging area as the origin. T x T The axis points to the north in the horizontal plane of the image, o T y T The axis is perpendicular to the specified point, o T -x T y T z T is a right-hand rectangular coordinate system, and the auxiliary system is the translation of the target system. The origin of the target system is translated to the target height plane just below the platform at the moment of imaging. S x S The axis points north in the target altitude plane, o S y S The axis is perpendicular to the ground, o S -x S y S z S It is a right-handed rectangular coordinate system.

3. The one-dimensional angular positioning method for a SAR moving target with a known target height according to claim 2, characterized in that: In step S1, the specific processing process is as follows: S11: Calculate the amplitude and phase of the ratio of the azimuth difference channel to the sum channel of the complex image data of the pixel where the target is located. The complex data of the sum channel and the azimuth difference channel are in the following form: Among them, Σ, Σ I and Σ Q are the complex, real and imaginary parts of the channel pixels, Δ, Δ I and Δ Q are the complex number, real part and imaginary part of the difference channel pixel respectively, and j is the imaginary unit; The difference and ratio are as follows: The magnitude and phase of the difference and ratio are: S12: Calculate the azimuth angle measurement value by looking up the table interpolation based on the difference and ratio amplitude and the measured amplitude-angle curve, and judge the polarity of the angle measurement value by the polarity of the difference and ratio phase to obtain the azimuth angle measurement result φ Az .

4. The one-dimensional angular positioning method for a SAR moving target with a known target height according to claim 3, characterized in that: In step S2, the specific processing process is as follows: S21: Calculate the antenna system beam center vector based on the antenna beam pointing angle as follows: Among them, A is the beam center vector of the antenna system, A x 、A y 、A z are the three-dimensional coordinates of vector A, α and β are the azimuth and elevation pointing angles of the antenna beam respectively; S22: Calculate the antenna system beam center line of sight angle based on the geometric relationship as follows: in, and They are the azimuth and elevation line of sight angles of the beam center, and the geometric definitions of the azimuth and elevation line of sight angles are line of sight and o A -y A x A and o A -z A x A The angle between S23: Calculate the target azimuth sight angle based on the target azimuth angle measurement result and the beam center sight angle in, is the result of azimuth angle measurement; S24: According to the target direction to the sight angle and target slope range R T Calculate the z-direction coordinate A of the target under the antenna system Tz :

5. The one-dimensional angular positioning method for a SAR moving target with a known target height according to claim 4, characterized in that: In step S3, the specific processing process is as follows: S31: Calculate the coordinate transformation matrix M from the auxiliary system to the antenna system: Among them, M0~M8 are the elements of matrix M, M st and M at They are the antenna installation angle conversion matrix and the platform attitude angle conversion matrix respectively; S32: Based on the conversion relationship from the auxiliary system to the antenna system, the target slant range, and the platform relative to the target height information in the target system, the conversion relationship from the auxiliary system to the antenna system is as follows: The system of equations is as follows: Among them, A T is the target vector under the antenna system, A Tx 、A Ty 、A Tz is vector A T The three-dimensional coordinates, S T is the target vector in the auxiliary frame, S Tx 、S Ty 、S Tz is the vector S T The three-dimensional coordinates of the target system, H is the relative height between the platform and the target; M6, M7, M8, A Tz 、R T , H are known quantities; Then the system of equations is simplified to a system of two-variable quadratic equations as follows: S33: Solve the above quadratic equations to obtain the target vector coordinates 1 and 2 in the auxiliary system: in, 6. The one-dimensional angular positioning method for a SAR moving target with a known target height according to claim 5, characterized in that: In step S4, the specific processing process is as follows: S41: Calculate the target vector A in the antenna system according to the auxiliary system target vector coordinates obtained in step S3 and the conversion relationship from the auxiliary system to the antenna system. T_i =[A Tx_i A Ty_i A Tz_i ] T , i=1,2 correspond to target vector coordinate 1 and target vector coordinate 2 respectively; S42: Calculate the elevation sight angle of the target under the antenna system according to the antenna system beam center sight angle formula S43: Compare the target pitching angle to the sight line with the beam center pitching angle to obtain the target pitching angle deviation S44: Determine the validity of the target vector based on the target elevation sight angle deviation: If the target is within the main lobe of the antenna beam, that is, the target elevation sight angle deviation is less than half the beam width, the target vector coordinates are determined to be valid; otherwise, they are invalid.

7. The one-dimensional angular positioning method for a SAR moving target with a known target height according to claim 6, characterized in that: In step S44, the validity judgment expression is as follows: Among them, θ El is the antenna elevation beamwidth.

8. The one-dimensional angular positioning method for a SAR moving target with a known target height according to claim 6, characterized in that: In step S5, the target three-dimensional coordinates are calculated using the formula: Among them, T x 、T y 、T z is the three-dimensional coordinate of the target in the target system, P x 、P y 、P z is the target system platform coordinate, that is, the target system platform position.

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