A pointing model based XY mount type antenna calibration method

Abstract

The application discloses a kind of XY pedestal type antenna calibration method based on pointing model, belong to antenna control technical field.The method includes: according to the structural characteristics of XY pedestal antenna, the axis system error term is determined, and the pointing error model is established in XY coordinate system;Using the principle of multivariate Newton iteration to establish reverse real-time correction model, solve transcendental equation;Select calibration radio source, adopt XY axis system grating scanning to obtain power spectral density diagram, determine signal center by Gaussian fitting, record theoretical angle and actual angle;Based on least square method, the error model parameters are fitted, and the reverse real-time correction model is used for multiple iterations until the accuracy requirement is met;Finally, according to error coefficient, the antenna pointing is compensated in real time.The application establishes the pointing error model under XY coordinate system, gives each axis system error term clear physical meaning, can assist artificial to complete antenna pedestal calibration debugging, effectively improves the pointing accuracy of XY pedestal type antenna.

Description

Technical Field

[0001] This invention relates to the field of antenna control technology, and in particular to a calibration method for XY mount antennas based on a pointing model. Background Technology

[0002] To meet the measurement accuracy requirements of different telemetry and control tasks and achieve precise antenna pointing and tracking, the measurement accuracy standards for ground antennas are becoming increasingly stringent, which also places higher demands on the precise calibration of antennas. Currently, conventional calibration methods can calibrate various errors of receiving antennas. However, modern antennas operate at increasingly higher frequencies and shorter wavelengths, making the construction of calibration towers insufficient for far-field calibration requirements. Therefore, towerless antenna calibration methods based on different error models have become a current research hotspot.

[0003] Regarding antenna calibration, researchers have done considerable work on the theory and testing of towerless calibration, and have successfully applied it to antennas of different apertures, frequency bands, and mount types. In related work, researchers have extensively designed and applied AE-mount antennas, with relatively mature error fitting and calibration models and a complete towerless calibration process. However, for XY-mount antennas, due to significant differences in coordinate transformation and operating mode compared to AE-mount antennas, error fitting and calibration typically require transforming the antenna angle from the XY coordinate system to the AE coordinate system before applying the pointing error model of the AE-mount antenna. However, due to the differences in antenna structure, the error terms in the pointing error model of the AE-mount antenna have no clear physical meaning in the XY-mount antenna, and the obtained error term coefficients cannot be used for antenna mount calibration and debugging.

[0004] In summary, in order to improve the pointing error fitting and calibration technology of XY mount antennas and assist in the calibration and debugging of antenna mounts, it is necessary to establish a pointing error model based on the XY coordinate system for the structure of XY mount antennas, give clear physical meaning to the error terms of each axis of the antenna, and ultimately improve the pointing accuracy of the antenna. Summary of the Invention

[0005] To address the problems existing in the above-mentioned XY mount antenna calibration technology, this invention provides an XY mount antenna calibration method based on a pointing model. The pointing model of the antenna is established in the XY coordinate system, giving clear physical meaning to the errors of each axis of the antenna.

[0006] The technical solution adopted in this invention is as follows:

[0007] A calibration method for XY mount antennas based on a pointing model includes the following execution process:

[0008] Step 1: Based on the structural characteristics of the XY mount antenna, determine the error terms of each axis that affect the antenna pointing accuracy, and derive and calculate each axis error term in the XY coordinate system, expressing it as a function of the antenna's X-axis and Y-axis rotation angles, and establish the antenna pointing error model;

[0009] Step 2: Based on the antenna pointing error model, using the multivariate Newton iteration principle, the actual pointing angle of the antenna is taken as the initial value, the iterative formula of the actual reference angle of the antenna is derived, the transcendental equation is solved, and a reverse real-time correction model for the antenna axis error is established.

[0010] Step 3: Based on the antenna's operating frequency band, select the calibration signal radio source for that operating frequency band, generate guidance data using the grating scanning method, control the antenna to perform grating scanning on the spatial domain surrounding the radio source in the XY axis system, obtain the power spectral density map of that spatial domain, determine the center point of the measured power spectral signal using the Gaussian fitting method, and record the theoretical and actual angles of the antenna.

[0011] Step 4: Using the theoretical and actual antenna angles recorded in Step 3, fit the pointing error model based on the least squares fitting method, calculate the pointing error model parameters, and iterate the antenna calibration results multiple times based on the inverse real-time correction model until the antenna meets the accuracy requirements. Record the coefficients of each axis error term at the current time.

[0012] Furthermore, in step 1, the axis error terms affecting antenna pointing accuracy specifically include six error terms: the error coefficient of the Y-axis and X-axis non-orthogonality. X-axis non-horizontal error coefficient Electric axis northward error coefficient Error coefficient between the electric axis and the Y-axis (not perpendicular) X-axis zero-point error coefficient Y-axis zero point error coefficient ;

[0013] The total X-axis pointing error is obtained by linearly superimposing the six error terms. and total Y-axis pointing error :

[0014]

[0015]

[0016] in, and These are the theoretical pointing angles of the antenna on the X and Y axes, respectively;

[0017] , Used to indicate the actual pointing angle of the antenna on the X-axis. and the actual pointing angle of the Y-axis This forms the antenna pointing error model in the XY coordinate system.

[0018] Furthermore, step 2, the establishment and iterative solution of the reverse real-time correction model, specifically includes the following processes:

[0019] At a certain moment, the reference values ​​for the antenna's X-axis and Y-axis pointing angles are... and The actual reference angle of the antenna to be solved is and ,

[0020] The relationship between the reference value, the actual reference angle, and the pointing error coefficient is expressed as follows:

[0021]

[0022] Will and , respectively represented as and function and f An iterative method is used to approximate the solution, and the iteration matrix is ​​represented as follows:

[0023]

[0024] Based on the above iteration matrix, let

[0025] ,

[0026] ,

[0027] Then follow the iterative formula Iterative calculations are performed, and the actual reference angle of the antenna is obtained when the iteration error is less than the set error threshold. and An approximate solution is obtained and used as the actual reference angle for the antenna in the antenna control system.

[0028] Furthermore, the grating scanning method described in step 3 specifically includes: taking the theoretical position of the radio source as the center, setting the scanning range and step size, first fixing the Y-axis angle, scanning the X-axis step size, then scanning the X-axis step size again until the entire rectangular spatial domain is covered, forming a grating scanning path; each scanning point is paused for a preset integration time, power spectrum data is collected, and a two-dimensional power spectral density map is generated.

[0029] Furthermore, the Gaussian fitting method described in step 3 specifically includes: after filtering the power spectral density map data, fitting it with a two-dimensional Gaussian function, extracting the coordinates of the extreme points obtained from the fitting as the signal center point, and recording the antenna angle corresponding to the center point as the actual pointing angle.

[0030] Furthermore, in step 4: the theoretical and actual pointing angle data of the antenna tracking the radio source in step 3 are fitted using the least squares fitting method based on the pointing error model in step 1, and the coefficients of the 6 error terms in the error model are calculated; then the 6 error term coefficients are substituted into the iteration matrix of the reverse real-time correction model established in step 2, and the antenna calibration results are iterated multiple times until the antenna meets the accuracy requirements.

[0031] The beneficial effects of this invention are:

[0032] A pointing error model for the antenna was established in the XY coordinate system. This model clarifies the actual physical meaning of the error terms of each axis of the antenna, which can assist in the calibration and debugging of the antenna mount and further improve the pointing accuracy of the antenna.

[0033] A reverse real-time correction model for antenna axis system error was established, and the transcendental equation was solved using the multivariate Newton iteration principle. It can converge to the desired accuracy through several simple iterations, which is beneficial for the coding and engineering application of the correction model.

[0034] To address the structural characteristics of XY mount antennas, a grating scanning method based on the XY axis was designed, which significantly reduces coordinate transformation errors during the antenna scanning of radio signal sources and helps improve the pointing accuracy of the antenna after calibration. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of an XY mount type antenna.

[0036] Figure 2 It is a power spectral density map obtained by grating scanning.

[0037] Figure 3 The signal center was obtained using Gaussian fitting.

[0038] Figure 4 This is a curve comparing the errors before and after antenna X-axis calibration.

[0039] Figure 5 This is a curve comparing the error before and after antenna Y-axis calibration. Detailed Implementation

[0040] The present invention will now be further described with reference to the accompanying drawings and corresponding embodiments.

[0041] This invention provides a calibration method for XY mount antennas based on a pointing model.

[0042] The specific steps of this invention are as follows:

[0043] Step 1: Based on the structural characteristics of the XY mount antenna, establish the antenna pointing error model.

[0044] An XY mount type antenna is shown in the attached figure. Figure 1 As shown, in an XY mount antenna system, there are two steering axes: the X-axis and the Y-axis. Due to factors such as tolerances, impacts, vibrations, and temperature differences during manufacturing, transportation, assembly, and use, the actual antenna structure may have many error terms. These error terms will cause the antenna's pointing accuracy to deviate from the ideal situation. There are six error terms affecting the pointing accuracy of an XY antenna, each represented by a coefficient... ~ express:

[0045] 1. Error coefficient of Y-axis and X-axis non-orthogonality ;

[0046] 2. X-axis non-horizontal error coefficient ;

[0047] 3. Electrical axis north-pointing error coefficient ;

[0048] 4. Error coefficient for non-perpendicularity between electrical axis and Y-axis ;

[0049] 5. X-axis zero-point error coefficient ;

[0050] 6. Y-axis zero-point error coefficient .

[0051] Assume the theoretical pointing angles of the antenna on the X and Y axes are respectively and The pointing errors caused by the above six error terms on the antenna's X and Y axes can be expressed as follows:

[0052]

[0053]

[0054] The actual pointing angles of the antenna on the X and Y axes can be expressed as follows: , .

[0055] Step 2: Based on the pointing error model in Step 1, establish a reverse real-time correction model for antenna axis error.

[0056] Suppose that at a certain moment, the reference values ​​for the antenna's X-axis and Y-axis pointing angles are... and In ideal circumstances, the reference value and Should be in accordance with the antenna's theoretical pointing angle and Although they are equal, various errors can cause differences between them, so the reference value cannot be directly used. and This serves as the reference angle for the antenna. Meanwhile, the antenna pointing error correction formula derived in step one is based on the theoretical pointing angle of the antenna. and Calculated. Therefore, it needs to be based on and The actual reference angle of the antenna during actual operation is calculated in reverse, and here it is taken as... and This indicates that the antenna mount angle is different from the actual reference angle. and When they match, the actual pointing angle of the antenna is the same as the theoretical pointing angle. and Consistent, achieving optimal pointing accuracy. Reference value. and can be and and pointing error coefficient ~ It is expressed as follows:

[0057]

[0058]

[0059] The reverse real-time correction model for the antenna, i.e., given the antenna reference value. and Real-time solution of the actual reference angle of the antenna and The process.

[0060] Will and They are respectively represented as and function and Because this function contains too many nonlinear factors and is a transcendental equation, it cannot be directly solved in the hardware controller. Therefore, an iterative method is used for approximate solution, and the iteration matrix can be represented as follows:

[0061]

[0062] Based on the above iteration matrix,

[0063] make , Then follow the iterative formula By performing iterative calculations, the actual reference angle of the antenna can be obtained when the iteration error is less than the set error threshold. and An approximate solution is obtained and used as the actual reference angle for the antenna, which is then directly applied to the antenna control system.

[0064] Step 3: Design the scanning method and data processing method for the antenna through-beam power supply.

[0065] Next, the antenna scanning method is designed to ensure that the antenna can be aligned with the signal center of the radio source during tracking, thereby recording the calibration data such as the actual pointing angle and the theoretical pointing angle of the antenna. In this invention, a grating scanning method is used to obtain the target center point.

[0066] After selecting a radio star as the calibration signal source and calculating its position, a grating scanning calculation method is used to generate guiding data to control the antenna to perform a grating scan of the entire spatial domain surrounding the radio star, obtaining the power spectral density map of the entire spatial domain. The power spectral density map of a certain XY mount antenna during calibration is attached. Figure 2 As shown in the figure. Then, after filtering the power spectral density data, Gaussian fitting is performed to obtain the measured values ​​of the beam center, thus minimizing the introduction of observation errors. The signal center obtained by the Gaussian fitting method is shown in the attached figure. Figure 3 As shown.

[0067] Step 4: Solve the error model parameters and calibrate the antenna to improve the antenna pointing accuracy.

[0068] The theoretical and actual pointing angles from step 3, when the antenna tracks the radio source, are used to fit the pointing error model from step 1 using the least squares fitting method. The coefficients of the six error terms in the error model are then calculated. ~ Then, the coefficients of the six error terms are substituted into the iteration matrix of the reverse real-time correction model established in step 2, and the antenna calibration results are iterated multiple times until the antenna meets the accuracy requirements. The error comparison curves before and after calibration of a certain XY mount antenna are shown in the attached figure. Figure 4 Appendix Figure 5 As shown.

[0069] At the same time, according to the coefficients of the six error terms calculated... ~ The mechanical mounting components of the antenna mount can be manually adjusted to improve the antenna pointing accuracy from a hardware perspective.

Claims

1. A calibration method for XY mount antennas based on a pointing model, characterized in that, The execution process includes the following steps: Step 1: Based on the structural characteristics of the XY mount antenna, determine the error terms of each axis that affect the antenna pointing accuracy, and derive and calculate each axis error term in the XY coordinate system, expressing it as a function of the antenna's X-axis and Y-axis rotation angles, and establish the antenna pointing error model; Step 2: Based on the antenna pointing error model, using the multivariate Newton iteration principle, take the actual pointing angle of the antenna as the initial value, derive the iterative formula of the actual reference angle of the antenna, solve the transcendental equation, and establish a reverse real-time correction model for the antenna axis error. Step 3: Based on the antenna's operating frequency band, select the calibration signal radio source for that operating frequency band, generate guidance data using the grating scanning method, control the antenna to perform grating scanning on the spatial domain surrounding the radio source in the XY axis system, obtain the power spectral density map of that spatial domain, determine the center point of the measured power spectral signal using the Gaussian fitting method, and record the theoretical and actual angles of the antenna. Step 4: Using the theoretical and actual antenna angles recorded in Step 3, fit the pointing error model based on the least squares fitting method, calculate the pointing error model parameters, and iterate the antenna calibration results multiple times based on the inverse real-time correction model until the antenna meets the accuracy requirements. Record the coefficients of each axis error term at the current time.

2. The XY mount antenna calibration method based on a pointing model according to claim 1, characterized in that, In step 1, the axis error terms affecting antenna pointing accuracy specifically include six error terms: the Y-axis and X-axis non-orthogonality error coefficient. X-axis non-horizontal error coefficient Electric axis northward error coefficient Error coefficient between the electric axis and the Y-axis (not perpendicular) X-axis zero-point error coefficient Y-axis zero point error coefficient ; The total X-axis pointing error is obtained by linearly superimposing the six error terms. and total Y-axis pointing error : ， ， in, and These are the theoretical pointing angles of the antenna on the X and Y axes, respectively; , Used to indicate the actual pointing angle of the antenna on the X-axis. and the actual pointing angle of the Y-axis This forms the antenna pointing error model in the XY coordinate system.

3. The XY mount antenna calibration method based on a pointing model according to claim 2, characterized in that, Step 2, the establishment and iterative solution of the reverse real-time correction model, specifically includes the following processes: At a certain moment, the reference values ​​for the antenna's X-axis and Y-axis pointing angles are... and The actual reference angle of the antenna to be solved is and , The relationship between the reference value, the actual reference angle, and the pointing error coefficient is expressed as follows: ， ， Will and , respectively represented as and function and f An iterative method is used to approximate the solution, and the iteration matrix is ​​represented as follows: ， Based on the above iteration matrix, let ， ， Then follow the iterative formula Iterative calculations are performed, and the actual reference angle of the antenna is obtained when the iteration error is less than the set error threshold. and An approximate solution is obtained and used as the actual reference angle for the antenna in the antenna control system.

4. The XY mount antenna calibration method based on a pointing model according to claim 1, characterized in that, Step 3 of the grating scanning method specifically includes: taking the theoretical position of the radio source as the center, setting the scanning range and step, first fixing the Y-axis angle, scanning the X-axis step, then stepping the Y-axis and repeating the X-axis scanning until the entire rectangular space is covered, forming a grating scanning path; each scanning point stays for a preset integration time, collects power spectrum data, and generates a two-dimensional power spectral density map.

5. The XY mount antenna calibration method based on a pointing model according to claim 1, characterized in that, The Gaussian fitting method described in step 3 specifically includes: after filtering the power spectral density map data, fitting it with a two-dimensional Gaussian function, extracting the coordinates of the extreme points obtained from the fitting as the signal center point, and recording the antenna angle corresponding to the center point as the actual pointing angle.

6. The XY mount antenna calibration method based on a pointing model according to claim 1, characterized in that, In step 4: The theoretical and actual pointing angle data of the antenna tracking the radio source in step 3 are fitted using the least squares fitting method based on the pointing error model in step 1, and the coefficients of the 6 error terms in the error model are calculated. Then, the coefficients of the six error terms are substituted into the iteration matrix of the reverse real-time correction model established in step 2, and the antenna calibration results are iterated multiple times until the antenna meets the accuracy requirements.

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