Complex target scattering center model reduction method
By performing first- and second-level reduction techniques on the scattering centers of complex targets and combining multiple scattering centers, the problem of excessive number of scattering centers in the RF simulation system is solved, and effective simulation of composite target combat scenarios is achieved.
Patent Information
- Application Number
- CN202510053848.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-14
- Publication Date
- 2025-05-13
AI Technical Summary
The number of scattering centers of complex targets is huge, far exceeding the number of feed control channels of existing RF simulation systems, making it difficult to achieve effective simulation in semi-physical RF simulation.
By performing primary and secondary reduction techniques for the target scattering center model, combining sensor characteristics and darkroom testing environment, multi-scattering centers are combined to form an equivalent scattering center, which meets the number of feed channels requirements of the RF simulation system.
The effective reduction of the number of scattering centers is achieved, the simulation capability of the semi-physical RF simulation system is improved, and the existing system has the simulation capability of composite target combat scenarios.
Smart Images
Figure CN119986579A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of radar target characteristic modeling, and in particular relates to a complex target scattering center model reduction method. Background Art
[0002] Radar target characteristics are the target-related properties and features that are considered by the radar system when detecting and identifying the target. In the high-frequency region, the scattering of the target can be approximated as a local phenomenon, that is, the radar echo of the target can be equivalent to the local structure. These independent scattering sources are called equivalent scattering centers. With the improvement of modern radar technology, the scattering center theory of radar targets has developed rapidly. The scattering center model is widely used in real-time signal processing, target scattering echo simulation, target automatic identification and other fields due to its simplicity and fast calculation. The study of scattering centers and their models, including position distribution, scattering amplitude, phase, polarization characteristics, etc., has become an important issue of common concern in the fields of radar high-resolution technology, electromagnetic simulation technology, and target scattering characteristics research.
[0003] The location of the physical scattering center of the target is determined by the structure and material parameters of the target itself. According to electromagnetic theory, the scattering center is located at the numerical discontinuity (geometric discontinuity and curvature discontinuity) of the STRATTON-CHU integral equation and the stationary phase point of the induced current. Therefore, the number of physical scattering centers of the target is large. Due to the complex geometric structure of the target, there are many types of scattering mechanisms, including reflection, diffraction, traveling waves, creeping waves, etc. of regular metal structures, as well as multiple diffraction and multiple reflections of complex structures such as irregular metal structures, thin coatings, and deep cavities. The formation mechanism of the physical scattering center of the target is complex, and the amplitude of the scattering center has complex frequency dependence, azimuth dependence, and polarization dependence.
[0004] The scattering center model is a parametric simulation algorithm for electromagnetic scattering following the full-wave numerical method and the high-frequency approximation method. The scattering center model does not include complex electromagnetic scattering processes, and parametrically characterizes different scattering mechanisms using analytical expressions with a small number of parameters. It can describe the changing characteristics of the electromagnetic scattering response of radar detection objects with the incident frequency, viewing angle, polarization, and physical properties of the object. Therefore, the scattering center model simplifies the complexity of electromagnetic calculations and significantly improves the simulation efficiency. It is one of the most effective simulation methods for realizing electromagnetic simulation of large radar targets or scenes.
[0005] The number of physical scattering centers of complex targets is huge, and it is necessary to reduce the number of scattering centers to form equivalent energy centers that match the sensor limited parameters and internal field limited conditions for internal field reproduction, so that the existing RF simulation system has the ability to simulate complex target combat scenarios.
[0006] In the development of modern weapon systems, field tests are essential. However, due to the high risk and high cost of field tests, especially for high-precision weapon systems, unlimited field tests are impossible, so the success rate of field tests must be improved, making the early indoor simulation experiments indispensable. Semi-physical RF simulation has developed in this context. Today, some of the world's major military powers have established semi-physical RF simulation laboratories, such as the missile simulation laboratory at Eglin Air Force Base in Florida, the United States, the Army Advanced Simulation Center, and Marconi in the United Kingdom. Semi-physical RF simulation is also called physical in-loop RF simulation.
[0007] When solving the simulation problem of complex targets in semi-physical RF systems, since the scattering center of the target is determined by the structure and material parameters of the target itself, when the geometric structure of the target is very complex or the material parameters are very complex, the number of scattering centers of the target will also be very large, which may be thousands or even tens of thousands. However, the measurement conditions of the actual darkroom are limited, and the number of feed control channels in the darkroom test environment is generally dozens or hundreds, so the number of feed channels in the actual darkroom test environment is usually less than the number of scattering centers of the target. Therefore, in order to solve the problem that the number of scattering centers of actual complex targets far exceeds the number of feed control channels of the existing RF simulation system, the multi-scattering center reduction technology is applied to the target scattering center model, combined with the actual infield test environment, the scattering centers of complex targets are merged in the semi-physical RF simulation to achieve the effect of reducing the number of scattering centers, meet the requirements of the number of feed channels of the RF simulation system in the test environment, and maximize the use of infield test resources, so that the existing RF simulation system has the simulation capability of complex target combat scenarios. Summary of the invention
[0008] In view of this, the present invention provides a complex target scattering center model reduction method, which can realize the merging of scattering centers to the greatest extent, so that the existing radio frequency simulation system has the simulation capability of complex target combat scenarios.
[0009] The technical solution for implementing the present invention is as follows:
[0010] A complex target scattering center model reduction method, the specific process is:
[0011] First-level reduction of target scattering centers based on sensor characteristics: for the target scattering center model, the scattering centers with effective scattering contribution are screened out based on the sensor working parameters, and then the peak amplitude of the one-dimensional range image of each scattering center within the sensor working angle range is further discarded according to the set peak amplitude reduction threshold, and finally the multiple scattering centers with indistinguishable distances are merged to form equivalent scattering centers;
[0012] Perform secondary reduction of target scattering centers based on background coupling: divide the scattering center model into regions according to the number n of feeding channels in the darkroom, sort the amplitudes of the scattering centers in different regions of the model, and select the top m scattering centers, where m is the maximum number of scattering points that can be simulated by the feeding channel;
[0013] The final output is the scattering center model after secondary reduction.
[0014] Optionally, the present invention also includes a model verification link. After completing the first-level reduction of the target scattering center based on the sensor characteristics, the one-dimensional range image calculated by the reduced scattering center model is compared with the one-dimensional range image calculated by the original scattering center model. Only when the image similarity is higher than the similarity threshold, the second-level reduction link is entered.
[0015] Optionally, the similarity threshold in the present invention is 80%.
[0016] Optionally, the present invention screens out scattering centers with effective scattering contributions based on sensor operating parameters as follows: calculate the amplitude of each scattering center according to the sensor parameters, set a center amplitude reduction threshold, and determine whether it is less than the reduction threshold, if so, discard it, otherwise retain it.
[0017] Optionally, the present invention combines multiple scattering centers whose distances cannot be resolved, and the specific process is as follows:
[0018] A distance threshold is set according to the target array distance, and a judgment is made according to the distance threshold. When the distance between two scattering centers is greater than the distance threshold, the scattering centers are merged until the distances between the remaining scattering centers are no greater than the distance threshold.
[0019] Optionally, when the image similarity is lower than a similarity threshold, the present invention reduces at least one of a set center amplitude reduction threshold, a peak amplitude reduction threshold and a distance threshold.
[0020] Optionally, the one-dimensional range image of the present invention is:
[0021]
[0022] Where F(·) represents the antenna pattern, represents the elevation and azimuth angles of the sensor's main beam direction, represents the elevation and azimuth angles of each scattering center in the sensor coordinate system, f c represents the center frequency, f represents the actual operating frequency, α n represents the orientation dependence factor, A n represents the amplitude of the scattering center, pp represents the polarization mode, R nis the position vector of the scattering center in the global coordinate system, and k is the wave number.
[0023] Optionally, the present invention divides the scattering center model into regions according to the set rules and the number of feeding channels n in the darkroom, and the set rules are: using the sensor's observation angle to the target, calculate the maximum size of the target's two-dimensional projection at this angle, and divide the target into n regions at equal intervals from a two-dimensional perspective according to the target's two-dimensional maximum size at this angle, and then copy and restore the n divided regions to the actual three-dimensional model of the target.
[0024] Beneficial effects:
[0025] In order to solve the problem that the number of scattering centers of actual complex targets far exceeds the number of feed control channels of existing radio frequency simulation systems, the present invention performs multi-scattering center reduction technology on the target scattering center model and combines the scattering centers of complex targets in the semi-physical radio frequency simulation in combination with the actual indoor test environment, thereby achieving the effect of reducing the number of scattering centers, meeting the requirement on the number of feed channels of the radio frequency simulation system in the test environment, maximizing the use of indoor test resources, and enabling the existing radio frequency simulation system to have the simulation capability of complex target combat scenarios. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0027] Figure 1 is a flow chart of the method of the present invention;
[0028] Figure 2 To input the working parameters of the sensor;
[0029] Figure 3 To input the range gate threshold and other parameters;
[0030] Figure 4 The number of input feeding channels and the number of scattering points that can be simulated by a single feeding channel;
[0031] Figure 5 is the position of the unreduced forward scattering center;
[0032] Figure 6 is the position of the scattering center after subtraction from step 1 to step 4;
[0033] Figure 7 is the position of the scattering center after subtraction from step 5 to step 6;
[0034] Figure 8 This is the case where the scattering centers are grouped according to the feeding channels;
[0035] Fig. 9 To reduce the data information of the backscattering center (including position, amplitude and phase information);
[0036] Fig.10 Comparison of one-dimensional distance image results. DETAILED DESCRIPTION
[0037] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.
[0038] It should be noted that the following embodiments and features in the embodiments may be combined with each other in the absence of conflict; and, based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making any creative work are within the scope of protection of the present disclosure.
[0039] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein may be used to implement this device and / or practice this method.
[0040] The design principle of the present invention is:
[0041] First, the scattering mechanism generated by the target under the excitation of the incident wave is different due to the incident frequency, and the amplitude of the scattering center changes with the frequency; the scattering of the target has an azimuth characteristic, and the scattering centers perceived by the radar echo under different azimuth observations are different; the scattering of the target has a polarization characteristic, and some scattering centers only show strong scattering contributions under specific polarizations. Therefore, the present invention can screen out the scattering centers that provide effective scattering contributions under specific simulation conditions based on the frequency band, azimuth, polarization mode and other parameters of the sensor, thereby reducing the number of multiple scattering centers required for the simulation. In addition, due to the limited resolution of the sensor, the present invention further performs complex vector superposition on the scattering fields of the indistinguishable scattering centers according to the resolution of the sensor, and merges them into an equivalent scattering center.
[0042] Secondly, for composite targets, in addition to the physical scattering centers of the complex targets themselves, there are also scattering centers formed by coupling with the background. The number of scattering centers is huge. Even at specific frequencies, azimuths, and polarization modes, the number of observable effective scattering centers is still large, far exceeding the number of triplet feed control channels of the current RF system. Therefore, the present invention further reduces the effective scattering centers according to the background coupling effect.
[0043] The final energy center is obtained by secondary reduction of the number of target physical scattering centers.
[0044] The present application embodiment provides a complex target scattering center model reduction method, such as Figure 1 As shown, the specific process is:
[0045] First-level reduction of target scattering centers based on sensor characteristics: for the target scattering center model, the scattering centers with effective scattering contribution are screened out based on the sensor working parameters, and then the peak amplitude of the one-dimensional range image of each scattering center within the sensor working angle range is further discarded according to the set peak amplitude reduction threshold, and finally the multiple scattering centers with indistinguishable distances are merged to form equivalent scattering centers;
[0046] Perform secondary reduction of target scattering centers based on background coupling: divide the scattering center model into regions according to the number n of feeding channels in the darkroom, sort the amplitudes of the scattering centers in different regions of the model, and select the top m scattering centers, where m is the maximum number of scattering points that can be simulated by the feeding channel;
[0047] The final output is the scattering center model after secondary reduction.
[0048] The target scattering center model reduction method of the embodiment of the present application is described in detail below:
[0049] The modeling method of the scattering center model of the target in this embodiment can be implemented by various existing modeling methods, which will not be further described in this application. The reduction process of steps 1 to 3 below belongs to the first-level reduction, and the reduction process of steps 5 to 6 belongs to the second-level reduction.
[0050] Step 1: Input the sensor's operating parameters, such as frequency band, angle range, and polarization mode. Calculate the amplitude of each scattering center based on the sensor parameters (the "amplitude of the scattering center" refers to the intensity of the scattering center's contribution to the echo signal received by the radar). Set the center amplitude reduction threshold to determine whether it is less than the reduction threshold. If so, discard it, otherwise keep it. The input sensor operating parameters are as follows: Figure 2 shown.
[0051] In this step, the sensor refers to the key component or module in the radar system used to transmit and receive electromagnetic waves. The main task of the sensor is to detect the target and obtain the working parameters of the target's distance, speed, direction and other information. The working parameters of the sensor are used as input parameters for subsequent scattering center reduction. Different parameters will produce different reduction results.
[0052] This step is implemented based on the existing technology and is not the focus of this application, so it will not be described in detail here.
[0053] Step 2: Calculate the peak amplitude of the one-dimensional range profile (High Resolution Range Profile) of each scattering center within the working angle range of the sensor, and sort them according to the peak amplitude. The one-dimensional range profile calculation formula is shown in formula (1). Set the peak amplitude reduction threshold to determine whether the one-dimensional range profile of each scattering center is greater than the peak amplitude reduction threshold. If so, retain it, otherwise discard it.
[0054]
[0055] Where F(·) represents the antenna pattern, represents the elevation and azimuth angles of the sensor's main beam direction, represents the elevation and azimuth angles of each scattering center in the sensor coordinate system, f c represents the center frequency, f represents the actual operating frequency, α n represents the orientation dependence factor, A n represents the amplitude of the scattering center (complex number), pp represents the polarization mode, R n is the position vector of the scattering center in the global coordinate system, and k is the wave number.
[0056] This step uses the peak amplitude screening of the one-dimensional range image from the perspective of practical engineering applications. In practical engineering applications, research is usually not conducted on a single scattering center, as there are too many scattering centers and the number is too complicated. Instead, the overall echo signal formed by all the scattering centers of the target is processed. The one-dimensional range image is a method of displaying the overall echo signal of the target. That is, the peak value formed by a certain structure of the target as a whole is reduced through the one-dimensional range image, and this peak value may be formed by multiple scattering centers (it can be understood that one peak value corresponds to multiple scattering centers). In this way, multiple scattering centers can be reasonably reduced at the same time, such as Fig.10 shown.
[0057] Step 3: After the scattering center reduction is performed through the above steps 1 and 2, the spatial position of the scattering center retained after the above reduction is determined, and the distance between each scattering center is calculated, and the distance between the scattering centers is set to a range gate threshold. The scattering centers whose distance is less than the range gate threshold are merged to form equivalent scattering centers, thereby realizing the merging of multiple scattering centers with indistinguishable distances.
[0058] like Figure 3 As shown, the distance threshold input in this step includes a distance threshold value and a target array distance. The distance threshold value is set according to the target array distance. The larger the target array distance, the larger the set distance threshold value.
[0059] Calculate the position distance of each scattering center in the actual space (for example, the spatial coordinates of scattering center A are (1,1,1), and the spatial coordinates of scattering center B are (2,2,2), then the position distance between scattering centers AB is ), set the range gate threshold (i.e., the range gate threshold value), and merge the scattering centers whose distance is less than the range gate threshold value (for example, if the range gate threshold value is set to 2, then if the position distance between AB is less than 2, AB will be merged).
[0060] The distance between the target and the array will affect the setting of the distance gate threshold. Assuming that the target is 10 meters away from the array, the distance gate threshold should be 0.01 meters. If the target is 100 meters away from the array, the distance gate threshold should be 0.1 meters. It can be compared to a person standing in front of a target. When the distance is 10 meters, the person can see some details of the target clearly (the resolution of the human eye is 0.01 meters). When the distance is 100 meters, the details seen by the person are blurred (the resolution of the human eye is 0.1 meters). The relationship between the target and the array is the relationship between the target and the human eye. When it is relatively close, the distance gate threshold is relatively small, and when it is relatively far, the distance gate threshold is relatively large.
[0061] Step 4: Model verification. Compare the one-dimensional range image calculated by the reduced scattering center model with the one-dimensional range image calculated by the original scattering center model. When the image similarity is higher than the similarity threshold, for example, the similarity is higher than 80%, the reduction is completed. The similarity calculation formula is shown in Formula 2. Otherwise, return to step 1 and reduce the reduction threshold of steps 1 to 3, thereby increasing the number of scattering centers and improving the image similarity.
[0062]
[0063] in, Represents the average value of x and y.
[0064] Step 5: Determine the number of feeding channels n in the actual darkroom, and divide the three-dimensional target into n regions according to the set rules based on the actual target size. Each region corresponds to a geometric center. At the same time, map the result of this region division to the reduced scattering center model, that is, divide the scattering center model into n regions, such as Figure 8 shown.
[0065] The rule set in this step is: based on the sensor's observation angle of the target, calculate the maximum size of the target's two-dimensional projection at that angle (the maximum size of the target is usually different at different viewing angles. This is because the target is view-dependent, that is, the actual size of the target will vary depending on the viewing angle. Specifically: Viewing angle and target projection When observing the target from different angles, the actual three-dimensional size of the target will be projected onto the observation surface to form different two-dimensional projection sizes. The maximum size of the target depends on its projection in the viewing direction), according to the maximum two-dimensional size of the target at that angle, divide the target into n areas at equal intervals from a two-dimensional perspective, and then copy and restore these n divided areas to the actual three-dimensional model of the target. This step is not limited to the above-mentioned division rules, such as Figure 4 shown.
[0066] Step 6: Determine the maximum number of scattering points m that the feed channel can simulate, sort the amplitudes of the scattering centers in different areas of the scattering center model in step 5 ("the amplitude of the scattering center" refers to the intensity of the contribution of the scattering center to the echo signal received by the radar), determine the echo contribution of each scattering center, and select and retain the first m scattering centers.
[0067] Steps five and six are completely combined with actual engineering applications. From the perspective of actual testing, it is very necessary to use actual equipment to limit the reduction results of the scattering center model. Reductions are made based on the number of feeding channels in the existing RF simulation system in the actual field and the number of scattering points that the feeding channels can simulate. The reductions in steps one, two, and three are still based on a theoretical perspective. A preliminary reduction is first performed. Through a series of steps, many scattering centers with weaker scattering intensities and scattering centers with distances less than the sensor resolution in the scattering center model are reduced. Steps five and six are for application in actual RF simulation systems for testing. For example, if the number of feeding channels in this RF simulation system is 8, and the previous theoretical value is 16, then further reductions must be made to reach the conditions where the system can truly apply this scattering center model. Figure 5-7 shown.
[0068] Step 7: Output the reduced scattering center model, which contains the data information (amplitude, phase and position) of each scattering center, such as Fig. 9 shown.
[0069] The present invention spatially groups multiple scattering centers, performs complex vector merging on the scattering fields of the multiple scattering centers distributed in an angular space group, and forms an equivalent energy center for internal field physical reproduction.
[0070] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A complex target scattering center model reduction method, characterized in that: The specific process is: First-level reduction of target scattering centers based on sensor characteristics: for the target scattering center model, the scattering centers with effective scattering contribution are screened out based on the sensor working parameters, and then the peak amplitude of the one-dimensional range image of each scattering center within the sensor working angle range is further discarded according to the set peak amplitude reduction threshold, and finally the multiple scattering centers with indistinguishable distances are merged to form equivalent scattering centers; Perform secondary reduction of target scattering centers based on background coupling: divide the scattering center model into regions according to the number n of feeding channels in the darkroom, sort the amplitudes of the scattering centers in different regions of the model, and select the top m scattering centers, where m is the maximum number of scattering points that can be simulated by the feeding channel; The final output is the scattering center model after secondary reduction.
2. The complex target scattering center model reduction method according to claim 1, characterized in that: It also includes a model verification step. After completing the first-level reduction of the target scattering center based on the sensor characteristics, the one-dimensional range image calculated by the reduced scattering center model is compared with the one-dimensional range image calculated by the original scattering center model. When the image similarity is higher than the similarity threshold, the second-level reduction step is entered.
3. The complex target scattering center model reduction method according to claim 2, characterized in that: The similarity threshold is 80%.
4. The complex target scattering center model reduction method according to claim 1, characterized in that: The method of screening out the scattering centers with effective scattering contribution based on the sensor working parameters is as follows: calculating the amplitude of each scattering center according to the sensor parameters, setting a center amplitude reduction threshold, and judging whether it is less than the reduction threshold, if so, discarding it, otherwise retaining it.
5. The complex target scattering center model reduction method according to claim 4, characterized in that: The specific process of merging the multiple scattering centers whose distances cannot be resolved is as follows: A distance threshold is set according to the target array distance, and a judgment is made according to the distance threshold. When the distance between two scattering centers is greater than the distance threshold, the scattering centers are merged until the distances between the remaining scattering centers are no greater than the distance threshold.
6. The complex target scattering center model reduction method according to claim 5, characterized in that: When the image similarity is lower than the similarity threshold, at least one of the set center amplitude reduction threshold, peak amplitude reduction threshold and distance threshold is reduced.
7. The complex target scattering center model reduction method according to claim 1, characterized in that: The one-dimensional range image is: Where F(·) represents the antenna pattern, represents the elevation and azimuth angles of the sensor's main beam direction, represents the elevation and azimuth angles of each scattering center in the sensor coordinate system, f c represents the center frequency, f represents the actual operating frequency, α n represents the orientation dependence factor, A n represents the amplitude of the scattering center, pp represents the polarization mode, R n is the position vector of the scattering center in the global coordinate system, and k is the wave number.
8. The complex target scattering center model reduction method according to claim 1, characterized in that: According to the set rules, the scattering center model is divided into regions according to the number n of feeding channels in the darkroom. The set rules are: based on the observation angle of the sensor to the target, the maximum size of the two-dimensional projection of the target at this angle is calculated, and according to the two-dimensional maximum size of the target at this angle, the target is equally spaced into n regions from a two-dimensional perspective, and then the divided n regions are copied and restored to the actual three-dimensional model of the target.