A multi-mode composite guidance simulation test multi-band signal correction and compensation method

Abstract

This invention discloses a method for multi-band signal correction and compensation in multi-mode composite guidance simulation experiments. It is applicable to hardware-in-the-loop simulation experiments of multi-mode composite seekers using beam combiners in multi-mode composite guidance simulation systems. The method corrects and compensates for target simulation signals of different bands emitted by the laser, infrared, and radio frequency band target simulation system after passing through the beam combiner, solving the attenuation and distortion problems that occur after reflection or transmission of radio frequency, laser, and infrared target simulation signals through the beam combiner, thus ensuring the accuracy of composite target simulation. The advantages of this invention are that the simulation process more closely resembles the actual working process of multi-mode composite seekers and guided weapons, resulting in higher simulation accuracy. This method is simple, effective, and practical, with significant potential for widespread application.

Description

Technical Field

[0001] This invention belongs to the field of guidance technology, specifically relating to a method for multi-band signal correction and compensation in multi-mode composite guidance simulation experiments. Background Technology

[0002] Currently, performance evaluation and verification of guided weapons employing multi-mode composite seekers require the use of a multi-mode composite guidance hardware-in-the-loop simulation system to conduct in-the-loop simulation experiments. A typical multi-mode composite guidance hardware-in-the-loop simulation system consists of a microwave anechoic chamber, an array feeding system, a radar target simulation system, a laser / infrared target simulator, a beam combiner, an image generation computer, a five-axis turntable, a simulation computer, and a simulation control system. The radar target simulation system comprises an array feeding system and a radar echo simulator, while the laser / infrared target simulator consists of an infrared target simulation subsystem and a laser target simulation subsystem.

[0003] In the hardware-in-the-loop simulation test of multi-mode composite guidance, the laser and infrared signals generated by the laser / infrared target simulator are reflected by the beam combiner and enter the seeker's entrance pupil. The radio frequency signals generated by the radar target simulation system are transmitted through the beam combiner and enter the seeker's entrance pupil. These signals will be attenuated and distorted to varying degrees after being reflected or transmitted by the beam combiner. Compared with the hardware-in-the-loop simulation mode of the single-mode seeker that radiates directly to the seeker under test without going through the beam combiner, the target simulation accuracy will be reduced to a certain extent. In severe cases, it will cause the seeker to fail to capture the target signal, resulting in the failure of the simulation test.

[0004] Currently, target and background environmental signals in the radio frequency, laser, and infrared bands are generated by the target simulation system and projected directly onto the test seeker without any processing. Attenuation and distortion phenomena occur during transmission, and there is no specific solution for the correction and compensation of multi-band signals. Effective measures need to be taken to ensure that the target simulation signals of different bands reaching the entrance pupil of the seeker are not affected during transmission, to ensure that the accuracy of composite target simulation is controlled within a reliable range, and to ensure the smooth progress of composite guidance hardware-in-the-loop simulation experiments. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a method for multi-band signal correction and compensation in multi-mode composite guidance simulation experiments. This method is applicable to hardware-in-the-loop simulation experiments of multi-mode composite seekers using beam combiners. It corrects and compensates for target simulation signals of different bands emitted by the laser, infrared, and radio frequency band target simulation system after passing through the beam combiner, solving the attenuation and distortion problems that occur after the radio frequency, laser, and infrared target simulation signals are reflected or transmitted through the beam combiner, ensuring the accuracy of the composite target simulation. The advantages of this invention are that the simulation process more closely resembles the actual working process of multi-mode composite seekers and guided weapons, resulting in higher simulation accuracy. This method is simple in design, effective, and practical, with significant potential for widespread application.

[0006] The technical solution adopted by this invention to solve its technical problem includes the following steps:

[0007] Step 1: Laser signal correction and compensation;

[0008] Step 1-1: Direct projection of simulated laser target signal;

[0009] Under the condition that the signal transmission distance is the same as the exit pupil distance in the multi-mode composite guidance simulation experiment, the laser signal energy intensity of the simulated laser target signal emitted by the laser target simulation subsystem in the laser / infrared target simulator without a beam combiner was measured to be [value missing]. The signal transmission distance is the same as the exit pupil distance under the multi-mode composite guidance simulation test;

[0010] Steps 1-2: The simulated laser target signal is reflected by the beam combiner;

[0011] The measured energy intensity of the simulated laser signal emitted by the laser target simulation subsystem in the laser / infrared target simulator, after being projected onto the beam combiner and reflected, and reaching the entrance pupil of the seeker head, was as follows: ;

[0012] Steps 1-3: Divide the beam combiner reflector surface into a grid for correction and compensation;

[0013] Based on the beamwidth of the laser signal entrance pupil, every... mm takes a sampling point, and the entire beam combiner reflector surface is equivalent to A discrete sampling point;

[0014] The energy intensity of the laser target simulation signal emitted by the laser target simulation subsystem in the laser / infrared target simulator, projected onto each sampling point of the beam combiner and reflected to the entrance pupil of the seeker, is denoted as: , Indicates the number of the sampling point;

[0015] Steps 1-4: Calculate the laser signal energy loss at each sampling point. ;

[0016] Steps 1-5: During the hardware-in-the-loop simulation experiment, the simulation computer compensates for the laser signal energy intensity based on the actual position (i,j) of the laser signal projected onto the beam combiner reflector when transmitting the laser signal energy intensity information to the laser target simulation subsystem in the laser / infrared target simulator. This achieves target simulation consistent with the case of direct projection of the laser target simulation signal in step 1-1; if the projection position of the laser target simulation signal is not at point (i,j), the magnitude of the laser signal energy intensity that needs to be compensated is calculated by interpolation using the four adjacent points around point (i,j);

[0017] Step 2: Infrared signal correction and compensation;

[0018] Step 2-1: Infrared signal energy intensity correction and compensation;

[0019] Step 2-1-1: Direct projection of infrared target analog signal;

[0020] Under the condition that the signal transmission distance is the same as the exit pupil distance in the multi-mode composite guidance simulation experiment, the infrared signal energy intensity of the infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator without a beam combiner was measured to reach the entrance pupil of the seeker. The signal transmission distance is the same as the exit pupil distance under the multi-mode composite guidance simulation test;

[0021] Step 2-1-2: The infrared target analog signal is reflected by the beam combiner;

[0022] The measured infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator with a beam combiner, after being projected onto the beam combiner and reflected, reaches the entrance pupil of the seeker at the following intensity: ;

[0023] Step 2-1-3: Divide the beam combiner reflector surface into a grid for correction and compensation. Based on the beamwidth of the infrared signal entrance pupil and considering the high resolution of infrared imaging, every... mm takes a sampling point, and the entire beam combiner reflector surface is equivalent to There are discrete sampling points, and the sampling point division is the same as in steps 1-3;

[0024] The infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator with a beam combiner is measured. The signal energy intensity of the infrared signal, after reflection at each sampling point of the beam combiner and reaching the entrance pupil of the seeker, is denoted as: ;

[0025] Step 2-1-4: Calculate the infrared signal energy loss at each sampling point. ;

[0026] Step 2-1-5: During the hardware-in-the-loop simulation experiment, when the simulation computer transmits the infrared signal energy intensity information to the infrared target simulation subsystem in the laser / infrared target simulator, it compensates for the infrared signal energy intensity based on the actual position (i,j) of the infrared signal projected onto the beam combiner reflector surface. This achieves target simulation consistent with the case of direct projection of infrared target simulation signal in step 2-1-1; if the projection position of infrared target simulation signal is not at point (i,j), the magnitude of infrared signal energy intensity to be compensated is calculated by interpolation using the four adjacent points around point (i,j);

[0027] Step 2-2: Infrared signal imaging distortion correction and compensation;

[0028] Step 2-2-1: Direct projection of image signal;

[0029] The image signal f(x,y) of the infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator without a beam combiner was measured to reach the entrance pupil of the seeker. The signal transmission distance was the same as the exit pupil distance under the multi-mode composite guidance simulation test.

[0030] Step 2-2-2: The image signal is reflected by the beam combiner;

[0031] The image signal g(x,y) is measured as follows: the infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator with a beam combiner is projected onto the beam combiner, reflected by it, and reaches the entrance pupil of the seeker.

[0032] Step 2-2-3: Calibration steps for distorted images;

[0033] When performing distortion correction, first find the center of symmetry, and then perform the corresponding geometric distortion correction process; the distortion correction steps are as follows:

[0034] a) Find the center of symmetry of the distorted image and convert the address space relationship represented by the distorted image into a spatial relationship with the center of symmetry as the origin;

[0035] b) Spatial transformation: The pixels in the input image, i.e. the distorted image, are rearranged to restore the original spatial relationship. That is, the address mapping relationship is used to find the corresponding point in the distorted image space for each point in the corrected image space.

[0036] c) Gray-scale interpolation: Assigning corresponding gray-scale values ​​to pixels after spatial transformation to restore the gray-scale values ​​at the original positions;

[0037] d) Determine the address mapping relationship in a rectangular coordinate system. Let [f(x,y)] be the original image and [f(u,v)] be the distorted image. The distortion correction method is to find the coordinate transformation from (u,v) to (x,y). That is, address mapping, and then let: , For parameter vectors;

[0038] If the distortion is merely a change in aspect ratio and tilt, then a mapping transformation is used to correct this distortion. ; , , Represent the integer closest to x; obtain the parameter. The problem is solved by estimation;

[0039] If the distortion is a spatially distorted geometric distortion, i.e., stretching of the rubber layer, it is a curvilinear distortion, which is simulated using a quadratic polynomial, and is expressed as:

[0040]

[0041] (1)

[0042] Obtain parameters The estimation of the distortion function is known, and the corrected space distortion map is obtained through the above quadratic polynomial transformation.

[0043] Step 3: Radio frequency signal correction and compensation;

[0044] The amplitude and phase errors of RF target signals of different frequency bands transmitted through the beam combiner are measured by a calibration device. During simulation, the amplitude and phase errors generated by the array feeding system transmitted through the beam combiner are corrected to offset the influence of the beam combiner on the RF target signal and ensure the accuracy of the RF target simulation.

[0045] The specific steps for radio frequency signal correction and compensation are as follows:

[0046] Step 3-1: Case without beam combiner;

[0047] Without installing a beam combiner, the array feed system generates system attenuator calibration tables, phase shifter calibration tables, attenuation-affected phase calibration tables, and phase shift-affected power calibration tables.

[0048] Step 3-1-1: Attenuator Calibration Table;

[0049] When generating the attenuator control code file, a separate attenuator control code file is generated for each frequency point.

[0050] The attenuator control code file consists of three dimensions: branch number (A, B, C), attenuation value, and attenuation control code. The attenuation control code is obtained by looking up the attenuation value.

[0051] Step 3-1-2: Phase shifter calibration table;

[0052] When generating the phase shifter control code file, a separate phase shifter control code file is generated for each frequency point. The phase shifter control code file consists of four dimensions: branch number (A, B, C), phase shift value, I-channel control code, and Q-channel control code. The phase shift control code is obtained by looking up the phase shift value.

[0053] Step 3-1-3: Attenuation Effect Phase Calibration Table;

[0054] When generating the attenuation effect phase shift file, a separate attenuation effect phase shift file is generated for each frequency point. The attenuation effect phase shift file consists of four dimensions: branch number (A, B, C), theoretical attenuation value, actual attenuation value, and phase shift value correction amount. The phase shift value correction amount is obtained by looking up the attenuation value.

[0055] Step 3-1-4: Power Calibration Table for Phase Shift Effects;

[0056] When generating the phase shift attenuation file, a separate phase shift attenuation file is generated for each frequency point. The phase shift attenuation file consists of four dimensions: branch number (A, B, C), theoretical phase shift value, actual phase shift value, and attenuation correction amount. The attenuation correction amount is obtained by looking up the phase shift value.

[0057] Step 3-2: Case with beam combiner;

[0058] After installing the beam combiner, the signal output from the array feed system will generate additional amplitude and phase errors when transmitted through the beam combiner. Therefore, the system amplitude and phase calibration table and the system amplitude and phase consistency correction table need to be recalibrated. After installing the beam combiner, the output signal power of each antenna on the antenna array needs to be calibrated.

[0059] The array calibration software controls the turntable, sending the corresponding angle code data to the turntable so that the LNB points to the position to be simulated on the array surface. The array calibration computer controls the vector network output, and the signal is transmitted to the array feed system through the RF cable. The array calibration computer controls the array feed control system through Ethernet and fiber optic networks, so that all antennas on the array surface output sequentially. The LNB of the calibration device receives the unloaded feed signal and connects the signal to the vector network signal analyzer to measure the received power and phase of each target signal, completing the calibration of the amplitude and phase of all antennas on the array surface and generating a system amplitude and phase calibration table after the beam combiner is installed. The array calibration software iterates multiple times based on the new system amplitude and phase calibration table to generate a system amplitude and phase consistency correction table after the beam combiner is installed.

[0060] When the amplitude and phase calibration table is generated, the path calibration data for each frequency point is generated into a separate calibration file. The calibration file consists of four dimensions: branch number (A, B, C), antenna number, phase shift value, and attenuation value. The phase shift value and attenuation value are obtained by looking up the antenna number.

[0061] Amplitude-phase consistency calibration uses a high-frequency head to measure the path loss and phase length of the array feed system. The measured data is used to generate an amplitude-phase compensation table to compensate for the link loss. The calibration program compensates for the loss and phase shift of each path and creates a corresponding storage table. The phase shifter and attenuator control words in each antenna branch are used to make their amplitude-phase characteristics the same as the reference signal until the amplitude-phase characteristics of each RF transmission path of all antennas are consistent and meet the technical parameter requirements.

[0062] Preferably, the solution process for equation (1) in step 2-2-3 is as follows:

[0063] Both equations in equation (1) are quadratic equations with six parameters. By taking six pairs of corresponding points on the distortion map and the correction map, the parameters can be obtained by solving the system of equations. The more corresponding point pairs are taken, the more parameters are obtained. The more accurate the estimate, the better;

[0064] If take For the corresponding point, it can be represented by a vector as follows:

[0065]

[0066]

[0067] coefficient , ;

[0068] Assuming that the matrix A formed by the m pairs of corresponding points is invertible, i.e., the m pairs of corresponding points are linearly uncorrelated, then the coefficients are calculated. : , ;

[0069] The correction process involves mapping each point on the correction image to the distortion image, and then obtaining the grayscale value of that point through grayscale interpolation. Therefore, the correction uses inverse address mapping.

[0070]

[0071] Bilinear interpolation uses the gray values ​​of the four nearest neighboring pixels around (u,v) to calculate the gray value at (u,v) according to the following method; let the four neighboring pixels of (u,v) be ABCD with coordinates (i,j), (i+1,j), (i,j+1), (i+1,j+1).

[0072] set up , ;

[0073] First, calculate the gray values ​​at points E and F, f(E) and f(F), where:

[0074] f(E) = [f(C)-f(A)]+f(A)

[0075] f(F) = [f(D)-f(B)]+f(B)

[0076] Then calculate (u,v): f(u,v) = [f(F)-f(E)]+f(E), where f(u,v) represents the gray value at (x,y) in the corrected image.

[0077] Preferably, the =50, =61.

[0078] The beneficial effects of this invention are as follows:

[0079] The multi-band signal correction and compensation method for multi-mode composite guidance simulation experiments provided by this invention corrects and compensates for target simulation signals of different bands emitted by laser, infrared, and radio frequency band target simulation systems after passing through a beam combiner. This solves the attenuation and distortion problems that occur after the radio frequency, laser, and infrared target simulation signals are reflected or transmitted through the beam combiner, ensuring the accuracy of composite target simulation. Using this method for hardware-in-the-loop simulation experiments more closely resembles the actual working process of multi-mode composite seekers and guided weapons, resulting in higher simulation confidence. This method is simple, effective, and practical, with significant potential for widespread application.

[0080] The method of this invention has also achieved good results in a hardware-in-the-loop simulation test of a surface-to-surface tactical missile employing a multi-mode composite seeker. In summary, this invention has many advantages and broad prospects for military applications. Attached Figure Description

[0081] Figure 1 This is a diagram showing the sampling points of the laser (infrared) signal on the reflector surface of the beam synthesizer of this invention.

[0082] Figure 2 This is a flowchart of the infrared signal imaging distortion correction and compensation algorithm of the present invention.

[0083] Figure 3 This is a schematic representation of the attenuation control code in an embodiment of the present invention.

[0084] Figure 4 This is a schematic representation of the phase-shift control code in an embodiment of the present invention.

[0085] Figure 5 This invention illustrates the effect of attenuation on phase calibration in an embodiment.

[0086] Figure 6 This invention illustrates the phase shift effect on power calibration.

[0087] Figure 7 A schematic diagram illustrating the radio frequency signal calibration principle of this invention.

[0088] Figure 8 A flowchart illustrating the amplitude and phase calibration process of an embodiment of the present invention.

[0089] Figure 9 Aspect-phase calibration table diagram of an embodiment of the present invention.

[0090] Figure 10 This is a schematic diagram of bilinear interpolation in an embodiment of the invention. Detailed Implementation

[0091] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0092] The technical problem to be solved by the present invention is to provide a method for multi-band signal correction and compensation in multi-mode composite guidance simulation test, so as to solve the attenuation and distortion problems that occur after the simulated signals of radio frequency, laser and infrared targets are reflected or transmitted through the beam synthesizer, and to ensure the accuracy of composite target simulation.

[0093] A method for multi-band signal correction and compensation in multi-mode composite guidance simulation experiments includes the following steps:

[0094] (1) Laser signal correction and compensation;

[0095] The main difference between the entrance pupil of a laser target analog signal directly projected onto the seeker and the entrance pupil of a laser target target signal reflected by a beam combiner is the energy intensity of the laser signal.

[0096] 1) The case of direct projection of simulated laser signals onto a target;

[0097] The measured energy intensity of the simulated laser signal emitted by the laser target simulation subsystem in the laser / infrared target simulator, reaching the entrance pupil of the seeker, was [value missing]. The signal transmission distance is the same as the exit pupil distance under the multi-mode composite guidance simulation test.

[0098] 2) The case where the simulated laser target signal is reflected by the beam combiner;

[0099] The measured energy intensity of the simulated laser signal emitted by the laser target simulation subsystem in the laser / infrared target simulator, after being projected onto the beam combiner and reflected, and reaching the entrance pupil of the seeker head, was as follows: .

[0100] Because the coating on the beam combiner's reflective surface has a certain degree of inhomogeneity, the physical effects of the reflected laser signal are not uniform. Therefore, it is necessary to divide the beam combiner's reflective surface into a grid for correction and compensation. The beam combiner has a diameter of 450mm. Based on the beamwidth of the laser signal's entrance pupil, a sampling point is taken every 50mm, effectively representing the entire beam combiner's reflective surface as 61 discrete sampling points. Figure 1 As shown.

[0101] The energy intensity of the laser target simulation signal emitted by the laser target simulation subsystem in the laser / infrared target simulator, projected onto each sampling point of the beam combiner and reflected to the entrance pupil of the seeker, is denoted as: .

[0102] 3) Calculate the laser signal energy loss at each sampling point. .

[0103] 4) During the hardware-in-the-loop simulation experiment, the simulation computer compensates for the laser signal energy intensity based on the actual position (i,j) of the laser signal projected onto the beam combiner reflector when transmitting the laser signal energy intensity information to the laser target simulation subsystem in the laser / infrared target simulator. This achieves target simulation consistent with the "direct projection of the simulated laser target signal". If the projection position of the simulated laser target signal is not at point (i,j), the magnitude of the laser signal energy intensity that needs to be compensated is calculated by interpolation using the four adjacent points around point (i,j).

[0104] (2) Infrared signal correction and compensation;

[0105] The main differences between the infrared target analog signal directly projected onto the seeker's entrance pupil and the signal reflected by the beam combiner are the energy intensity of the infrared signal and the distortion of the resulting image.

[0106] 1) Infrared signal energy intensity correction and compensation;

[0107] The case of direct projection of simulated infrared target signals;

[0108] The infrared signal energy intensity at the seeker entrance pupil of the laser / infrared target simulator, emitted by the infrared target simulation subsystem without a beam combiner, was measured to be [value missing]. The signal transmission distance is the same as the exit pupil distance under the multi-mode composite guidance simulation test.

[0109] The reflection of an infrared target's simulated signal after passing through a beam combiner;

[0110] The measured infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator with a beam combiner, after being projected onto the beam combiner and reflected, reaches the entrance pupil of the seeker at the following intensity: .

[0111] Because the coating on the beam combiner's reflective surface has a certain degree of inhomogeneity, the physical effect after infrared signal reflection is not uniform. Therefore, it is necessary to divide the beam combiner's reflective surface into a grid for correction and compensation. The beam combiner diameter is 450mm. Based on the beamwidth of the infrared signal entrance pupil and considering the high resolution of infrared imaging, a sampling point is taken every 50mm, making the entire beam combiner reflective surface equivalent to 61 discrete sampling points. The sampling point division and... Figure 1 same.

[0112] The infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator with a beam combiner is measured. The signal energy intensity of the infrared signal, after reflection at each sampling point of the beam combiner and reaching the entrance pupil of the seeker, is denoted as: .

[0113] Calculate the infrared signal energy loss at each sampling point. .

[0114] During the hardware-in-the-loop simulation experiment, when the simulation computer transmits the infrared signal energy intensity information to the infrared target simulation subsystem in the laser / infrared target simulator, it compensates for the infrared signal energy intensity based on the actual position (i,j) of the infrared signal projected onto the beam combiner reflector. This achieves target simulation consistent with the "direct projection of infrared target simulation signal". If the projection position of the infrared target simulation signal is not at point (i,j), the magnitude of the infrared signal energy intensity that needs to be compensated is calculated by interpolation using the four adjacent points around (i,j).

[0115] 2) Infrared signal imaging distortion correction and compensation;

[0116] The case of direct projection of image signals;

[0117] The image signal f(x,y) of the infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator without a beam combiner was measured to reach the entrance pupil of the seeker. The signal transmission distance is the same as the exit pupil distance under the multi-mode composite guidance simulation test.

[0118] The image signal is reflected after passing through a beam combiner;

[0119] The image signal g(x,y) is measured as follows: the infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator with a beam combiner is projected onto the beam combiner, reflected by it, and reaches the entrance pupil of the seeker.

[0120] Because the coating on the reflective surface of the beam synthesizer has a certain degree of inhomogeneity, geometric distortion will occur after the image is reflected.

[0121] Calibration steps for distorted images;

[0122] For distorted optical systems, straight lines in the distortion space are generally no longer straight lines in the image space, with the exception of straight lines passing through the center of symmetry. Therefore, when performing distortion correction, the center of symmetry must be found first, and then the corresponding geometric distortion correction process can be performed. The distortion correction steps are as follows:

[0123] a) Find the center of symmetry of the distorted image and convert the address space relationship represented by the distorted image into a spatial relationship with the center of symmetry as the origin.

[0124] b) Spatial Transformation: The pixels in the input image (distorted image) are rearranged to restore the original spatial relationships. That is, the address mapping relationship is used to find the corresponding point in the distorted image space for each point in the corrected image space.

[0125] c) Gray-scale interpolation: Assigning corresponding gray values ​​to pixels after spatial transformation to restore the original gray values.

[0126] Correcting geometric distortion requires geometric (coordinate) transformations, including conventional transformations such as parallel translation, rotation, and scaling. Here, we first determine the address mapping relationship in a Cartesian coordinate system; in the software, a matrix coordinate system is used. Let [f(x,y)] be the original image, and [f(u,v)] be the distorted image. The distortion correction method is to find the coordinate transformation from (u,v) to (x,y). (Address mapping), then let: , Let be the parameter vector. If the distortion is simply a change in aspect ratio and tilt, then the mapping transformation can correct this distortion. . , , This represents the integer closest to x. If the parameter can be obtained... If we can estimate the problem, it can be solved.

[0127] However, typical distortions are not simply changes in aspect ratio or tilt; they usually involve spatial distortion, i.e., stretching of the rubber layer. This is curvilinear distortion, which is simulated using a quadratic polynomial, expressed as:

[0128]

[0129]

[0130] Similarly, as long as the parameters can be obtained From the estimation of the distortion function, the corrected spatial distortion map can be obtained through the polynomial transformation in the above equation.

[0131] Both of the above equations are quadratic equations in two variables with six parameters. Therefore, by taking six pairs of corresponding points on each of the distortion and correction maps, the parameters can be obtained by solving the system of equations. Theoretically, the more corresponding point logarithms are taken, the more parameters can be obtained. The more accurate the estimate, the better. Let's assume... For the corresponding point, it can be represented by a vector as follows:

[0132]

[0133]

[0134] coefficient , .

[0135] Assuming that the matrix A formed by the m pairs of corresponding points is invertible, meaning that the m pairs of corresponding points are linearly uncorrelated, then the coefficients can be easily calculated. : , .

[0136] Because grayscale interpolation is used, the correction process involves mapping each point on the correction image to the distortion image, and then obtaining the grayscale value of that point through grayscale interpolation. Therefore, the correction uses inverse address mapping.

[0137] ( )

[0138] By address mapping ( The calculated (u,v) values ​​may be non-integer. However, in the distorted image [f(u,v)], pixel values ​​are only defined at integer coordinates. Therefore, pixel values ​​at non-integer coordinates are calculated using pixel values ​​at neighboring integer coordinates; this is called grayscale interpolation. Grayscale interpolation methods include nearest-neighbor interpolation and bilinear interpolation. Nearest-neighbor interpolation often produces jagged edges, while bilinear interpolation provides significantly higher accuracy. Generally, the accuracy of bilinear interpolation is sufficient for image processing, and higher-precision grayscale interpolation is not required; therefore, bilinear interpolation is used here.

[0139] Bilinear interpolation uses the gray values ​​of the four nearest neighboring pixels around (u,v) to calculate the gray value at (u,v) according to the following method. Let the four neighboring pixels of (u,v) be ABCD with coordinates (i,j), (i+1,j), (i,j+1), and (i+1,j+1).

[0140] set up , .

[0141] First calculate Figure 10 The gray values ​​at points E and F, f(E) and f(F), are given by:

[0142] f(E) = [f(C)-f(A)]+f(A)

[0143] f(F) = [f(D)-f(B)]+f(B)

[0144] Then calculate (u,v): f(u,v) = [f(F)-f(E)]+f(E), where f(u,v) represents the grayscale value at (x,y) in the corrected image. The algorithm flow for infrared signal imaging distortion correction and compensation is as follows: Figure 2 As shown.

[0145] (3) Radio frequency signal correction and compensation;

[0146] The main difference between the entrance pupil of the seeker and the entrance pupil of the radio frequency target analog signal directly projected onto the seeker head is the amplitude and phase changes of the radio frequency signal.

[0147] The amplitude and phase errors of RF target signals transmitted through the beam combiner are measured by a calibration device. During simulation, the amplitude and phase errors generated by the array feeding system transmitted through the beam combiner are corrected to offset the influence of the beam combiner on the RF target signal and ensure the accuracy of the RF target simulation.

[0148] The specific steps for radio frequency signal correction and compensation are as follows:

[0149] 1) Without a beam combiner;

[0150] Without installing a beam combiner, the array feed system generates system attenuator calibration tables, phase shifter calibration tables, attenuation-affected phase calibration tables, and phase shift-affected power calibration tables.

[0151] Attenuator calibration form;

[0152] When generating the attenuator control code file, a separate file is generated for each frequency point. The file is named AttNum_Ch_Frq, where Ch is the channel number and Frq is the frequency value.

[0153] The attenuator control code file consists of three dimensions: tributary number (A, B, C), attenuation value, and attenuation control code. The attenuation control code is obtained by looking up the attenuation value. The attenuation control code table is as follows: Figure 3 As shown.

[0154] Phase shifter calibration form;

[0155] Since the phase shifter uses a vector controller, the specific phase shift value and phase shift control code value need to be calibrated before they can be obtained. When generating the phase shifter control code file, a separate file is generated for each frequency point. The file is named PhaseNum_Ch_Frq, where Ch is the channel number and Frq is the frequency value. The phase shifter control code file consists of four dimensions: branch number (A, B, C), phase shift value, I-channel control code, and Q-channel control code. The phase shift control code is obtained by looking up the phase shift value. The phase shift control code table is as follows: Figure 4 As shown.

[0156] Attenuation affects phase calibration table;

[0157] When generating the attenuation-affected phase shift file, a separate file is generated for each frequency point. The file is named AttPhase_Ch_Frq, where Ch is the channel number and Frq is the frequency value. The attenuation-affected phase shift file consists of four dimensions: branch number (A, B, C), theoretical attenuation value, actual attenuation value, and phase shift correction. The phase shift correction is obtained by looking up the attenuation value. The attenuation-affected phase calibration table is as follows: Figure 5 As shown.

[0158] Phase shift effect power calibration table;

[0159] When generating the phase shift attenuation file, the phase shift attenuation data for each frequency point is generated into a separate file. The file is named PhaseAtt_Ch_Frq, where Ch is the channel number and Frq is the frequency value. The phase shift attenuation file consists of four columns: branch number (A, B, C), theoretical phase shift value, actual phase shift value, and attenuation correction. The attenuation correction is obtained by looking up the phase shift value. The phase shift power calibration table is shown below. Figure 6 As shown.

[0160] 2) Cases with beam combiners;

[0161] After installing the beam combiner, the signal output from the array feed system will generate additional amplitude and phase errors after transmission through the beam combiner. Therefore, the system amplitude and phase calibration table and the system amplitude and phase consistency correction table need to be recalibrated. After installing the beam combiner, the output signal power of each antenna on the antenna array is calibrated. The principle of RF signal calibration is as follows: Figure 7 As shown.

[0162] The array calibration software controls the turntable, sending corresponding angle code data to the turntable so that the LNB points to the position to be simulated on the array surface. The array calibration computer controls the vector network output, and the signal is transmitted to the array feed system via RF cable. The array calibration computer controls the array feed control system via Ethernet and fiber optic network, causing all antennas on the array surface to output sequentially. The LNB of the calibration device receives the unloaded feed signal and connects it to the vector network signal analyzer to measure the received power and phase of each target signal, completing the calibration of the amplitude and phase of all antennas on the array surface and generating a system amplitude and phase calibration table after the beam combiner is installed. The array calibration software iterates multiple times based on the new system amplitude and phase calibration table to generate a system amplitude and phase consistency correction table after the beam combiner is installed. The amplitude and phase calibration process is as follows: Figure 8 As shown.

[0163] When generating the amplitude and phase calibration table, path calibration data for each frequency point is generated into a separate file. The file is named PathAmend_Ch_Frq, where Ch is the channel number and Frq is a combination of frequency value and frequency unit. The calibration file consists of four columns: branch number (A, B, C), antenna number, phase shift value, and attenuation value. The phase shift value and attenuation value are obtained by looking up the antenna number. The amplitude and phase calibration table is as follows: Figure 9 As shown.

[0164] Amplitude and phase consistency calibration uses a LNB to measure the path loss and phase length of the array feed system. The measured data is used to generate an amplitude and phase compensation table to compensate for link losses. The calibration procedure compensates for the loss and phase shift of each path, creating corresponding stored tables. The amplitude and phase of each antenna branch are controlled by phase shifters and attenuators to ensure they are identical to the reference signal, until the amplitude and phase characteristics of all RF transmission paths of all antennas are consistent and meet the technical parameter requirements.

[0165] Example:

[0166] In a semi-physical simulation test of an air-to-ground missile, the guidance and control components involved in the simulation included a multi-mode composite seeker, inertial navigation system, onboard computer, and servo motors. The multi-mode composite seeker employed a laser, infrared, and radio frequency (RF) tri-mode composite guidance system. Before the test, the simulated laser, infrared, and RF target signals needed to be calibrated. During the test, signal compensation was performed. The specific implementation steps are as follows:

[0167] (1) Connect the simulation equipment and the test product;

[0168] (2) Correct the energy intensity of the laser signal;

[0169] (3) Correct the energy intensity of the infrared signal;

[0170] (4) Correct the imaging distortion of the infrared signal;

[0171] (5) Correct the amplitude and phase of the radio frequency signal;

[0172] (6) At this point, the hardware-in-the-loop simulation system has been calibrated and can be used for formal simulation tests;

[0173] (7) Compensation is provided for the attenuation and distortion of the simulated radio frequency, laser and infrared target signals after reflection or transmission through the beam synthesizer during the test.

Claims

1. A method for multi-band signal correction and compensation in multi-mode composite guidance simulation experiments, characterized in that, Includes the following steps: Step 1: Laser signal correction and compensation; Step 1-1: Direct projection of simulated laser target signal; Under the condition that the signal transmission distance is the same as the exit pupil distance in the multi-mode composite guidance simulation experiment, the laser signal energy intensity at the entrance pupil of the seeker head, emitted by the laser target simulation subsystem in the laser / infrared target simulator without a beam combiner, was measured to be: The signal transmission distance is the same as the exit pupil distance under the multi-mode composite guidance simulation test; Steps 1-2: The simulated laser target signal is reflected by the beam combiner; The measured energy intensity of the simulated laser signal emitted by the laser target simulation subsystem in the laser / infrared target simulator, after being projected onto the beam combiner and reflected, and reaching the entrance pupil of the seeker head, was as follows: ; Steps 1-3: Divide the beam combiner reflector surface into a grid for correction and compensation; Based on the beamwidth of the laser signal entrance pupil, every... mm takes a sampling point, and the entire beam combiner reflector surface is equivalent to A discrete sampling point; The energy intensity of the laser target simulation signal emitted by the laser target simulation subsystem in the laser / infrared target simulator, projected onto each sampling point of the beam combiner and reflected to the entrance pupil of the seeker, is denoted as: , Indicates the number of the sampling point; Steps 1-4: Calculate the laser signal energy loss at each sampling point. ; Steps 1-5: During the hardware-in-the-loop simulation experiment, the simulation computer compensates for the laser signal energy intensity based on the actual position (i,j) of the laser signal projected onto the beam combiner reflector when transmitting the laser signal energy intensity information to the laser target simulation subsystem in the laser / infrared target simulator. This achieves target simulation consistent with the case of direct projection of the laser target simulation signal in step 1-1; if the projection position of the laser target simulation signal is not at point (i,j), the magnitude of the laser signal energy intensity that needs to be compensated is calculated by interpolation using the four adjacent points around point (i,j); Step 2: Infrared signal correction and compensation; Step 2-1: Infrared signal energy intensity correction and compensation; Step 2-1-1: Direct projection of infrared target analog signal; Under the condition that the signal transmission distance is the same as the exit pupil distance in the multi-mode composite guidance simulation experiment, the infrared signal energy intensity of the infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator without a beam combiner was measured to reach the entrance pupil of the seeker. The signal transmission distance is the same as the exit pupil distance under the multi-mode composite guidance simulation test; Step 2-1-2: The infrared target analog signal is reflected by the beam combiner; The measured infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator with a beam combiner, after being projected onto the beam combiner and reflected, reaches the entrance pupil of the seeker at the following intensity: ; Step 2-1-3: Divide the beam combiner reflector surface into a grid for correction and compensation. Based on the beamwidth of the infrared signal entrance pupil and considering the high resolution of infrared imaging, every... mm takes a sampling point, and the entire beam combiner reflector surface is equivalent to There are discrete sampling points, and the sampling point division is the same as in steps 1-3; The infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator with a beam combiner is measured. The signal intensity of the infrared signal, after reflection at each sampling point of the beam combiner and reaching the entrance pupil of the seeker, is denoted as: ; Step 2-1-4: Calculate the infrared signal energy loss at each sampling point. ; Step 2-1-5: During the hardware-in-the-loop simulation experiment, when the simulation computer transmits the infrared signal energy intensity information to the infrared target simulation subsystem in the laser / infrared target simulator, it compensates for the infrared signal energy intensity based on the actual position (i,j) of the infrared signal projected onto the beam combiner reflector surface. This achieves target simulation consistent with the case of direct projection of infrared target simulation signal in step 2-1-1; if the projection position of infrared target simulation signal is not at point (i,j), the magnitude of infrared signal energy intensity to be compensated is calculated by interpolation using the four adjacent points around point (i,j); Step 2-2: Infrared signal imaging distortion correction and compensation; Step 2-2-1: Direct projection of image signal; The image signal f(x,y) of the infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator without a beam combiner was measured to reach the entrance pupil of the seeker. The signal transmission distance was the same as the exit pupil distance under the multi-mode composite guidance simulation test. Step 2-2-2: The image signal is reflected by the beam combiner; The image signal g(x,y) of the infrared target simulation signal emitted by the infrared target simulation subsystem in the laser / infrared target simulator with a beam combiner, after being projected onto the beam combiner and reflected by it, reaches the entrance pupil of the seeker. Step 2-2-3: Calibration steps for distorted images; When performing distortion correction, first find the center of symmetry, and then perform the corresponding geometric distortion correction process; the distortion correction steps are as follows: a) Find the center of symmetry of the distorted image and convert the address space relationship represented by the distorted image into a spatial relationship with the center of symmetry as the origin; b) Spatial transformation: The pixels in the input image, i.e. the distorted image, are rearranged to restore the original spatial relationship. That is, the address mapping relationship is used to find the corresponding point in the distorted image space for each point in the corrected image space. c) Gray-scale interpolation: Assigning corresponding gray-scale values ​​to pixels after spatial transformation to restore the gray-scale values ​​at the original positions; d) Determine the address mapping relationship in a rectangular coordinate system. Let [f(x,y)] be the original image and [f(u,v)] be the distorted image. The distortion correction method is to find the coordinate transformation from (u,v) to (x,y). That is, address mapping, and then let: , For parameter vectors; If the distortion is merely a change in aspect ratio and tilt, then a mapping transformation is used to correct this distortion. ; , , Represent the integer closest to x; obtain the parameter. The problem is solved by estimation; If the distortion is a spatially distorted geometric distortion, i.e., stretching of the rubber layer, it is a curvilinear distortion, which is simulated using a quadratic polynomial, and is expressed as: ； （1） Obtain parameters The estimation of the distortion function is known, and the corrected space distortion map is obtained through the above quadratic polynomial transformation. Step 3: Radio frequency signal correction and compensation; The amplitude and phase errors of RF target signals of different frequency bands transmitted through the beam combiner are measured by a calibration device. During simulation, the amplitude and phase errors generated by the array feeding system transmitted through the beam combiner are corrected to offset the influence of the beam combiner on the RF target signal and ensure the accuracy of the RF target simulation. The specific steps for radio frequency signal correction and compensation are as follows: Step 3-1: Case without beam combiner; Without installing a beam combiner, the array feed system generates system attenuator calibration tables, phase shifter calibration tables, attenuation-affected phase calibration tables, and phase shift-affected power calibration tables. Step 3-1-1: Attenuator Calibration Table; When generating the attenuator control code file, a separate attenuator control code file is generated for each frequency point. The attenuator control code file consists of three dimensions: branch number (A, B, C), attenuation value, and attenuation control code. The attenuation control code is obtained by looking up the attenuation value. Step 3-1-2: Phase shifter calibration table; When generating the phase shifter control code file, a separate phase shifter control code file is generated for each frequency point. The phase shifter control code file consists of four dimensions: branch number (A, B, C), phase shift value, I-channel control code, and Q-channel control code. The phase shift control code is obtained by looking up the phase shift value; Step 3-1-3: Attenuation Effect Phase Calibration Table; When generating the attenuation effect phase shift file, the attenuation effect phase shift data at each frequency point is generated into a separate attenuation effect phase shift file. The attenuation-affected phase shift file consists of four dimensions: branch number (A, B, C), theoretical attenuation value, actual attenuation value, and phase shift value correction amount. The phase shift correction value is obtained by looking up the attenuation value. Step 3-1-4: Power Calibration Table for Phase Shift Effects; When generating the phase shift attenuation file, the phase shift attenuation data at each frequency point is generated into a separate phase shift attenuation file. The phase shift attenuation file consists of four dimensions: branch number (A, B, C), theoretical phase shift value, actual phase shift value, and attenuation correction amount; the attenuation correction amount is obtained by looking up the phase shift value. Step 3-2: Case with beam combiner; After installing the beam combiner, the signal output from the array feed system will generate additional amplitude and phase errors when transmitted through the beam combiner. Therefore, the system amplitude and phase calibration table and the system amplitude and phase consistency correction table need to be recalibrated. After installing the beam combiner, the output signal power of each antenna on the antenna array needs to be calibrated. The array calibration software controls the turntable, sending the corresponding angle code data to the turntable so that the LNB points to the position to be simulated on the array surface; the array calibration computer controls the vector network output, and the signal is transmitted to the array feed system through the radio frequency cable. The array calibration computer controls the array feed control system through Ethernet and fiber optic network, so that all antennas on the array surface output in sequence. The LNB of the calibration device receives the unloaded feed signal and connects the signal to the vector network signal analyzer to measure the received power and phase of each target signal, complete the calibration of the amplitude and phase of all antennas on the array surface, and generate the system amplitude and phase calibration table after the beam combiner is installed. The array calibration software iterates multiple times based on the new system amplitude and phase calibration table to generate a system amplitude and phase consistency correction table after the beam combiner is installed. When the amplitude and phase calibration table is generated, the path calibration data for each frequency point is generated into a separate calibration file. The calibration file consists of four dimensions: branch number (A, B, C), antenna number, phase shift value, and attenuation value; the phase shift value and attenuation value are obtained by looking up the antenna number. Amplitude-phase consistency calibration uses a high-frequency head to measure the path loss and phase length of the array feed system. The measured data is used to generate an amplitude-phase compensation table to compensate for the link loss. The calibration program compensates for the loss and phase shift of each path and creates a corresponding storage table. The phase shifter and attenuator control words in each antenna branch are used to make their amplitude-phase characteristics the same as the reference signal until the amplitude-phase characteristics of each RF transmission path of all antennas are consistent and meet the technical parameter requirements.

2. The method for multi-band signal correction and compensation in multi-mode composite guidance simulation experiment according to claim 1, characterized in that, The solution process for equation (1) in step 2-2-3 is as follows: Both equations in equation (1) are quadratic equations with six parameters. By taking six pairs of corresponding points on the distortion map and the correction map, the parameters can be obtained by solving the system of equations. The more corresponding point pairs are taken, the more parameters are obtained. The more accurate the estimate, the better; If take For the corresponding point, it can be represented by a vector as follows: ； ； coefficient , ; Assuming that the matrix A formed by the m pairs of corresponding points is invertible, i.e., the m pairs of corresponding points are linearly uncorrelated, then the coefficients are calculated. : , ; The correction process involves mapping each point on the correction image to the distortion image, and then obtaining the grayscale value of that point through grayscale interpolation. Therefore, the correction uses inverse address mapping. Bilinear interpolation uses the gray values ​​of the four nearest neighboring pixels around (u,v) to calculate the gray value at (u,v) according to the following method; let the four neighboring pixels of (u,v) be ABCD with coordinates (i,j), (i+1,j), (i,j+1), (i+1,j+1). set up , ; First, calculate the gray values ​​at points E and F, f(E) and f(F), where: f(E)= [f(C)-f(A)]+f(A) f(F)= [f(D)-f(B)]+f(B) Then calculate (u,v): f(u,v) = [f(F)-f(E)]+f(E), where f(u,v) represents the gray value at (x,y) in the corrected image.

3. The method for multi-band signal correction and compensation in multi-mode composite guidance simulation experiment according to claim 1, characterized in that, The =50, =61.

Images