One-dimensional range profile simulation method based on space-time coding metasurface equivalent amplitude-phase synthesis

Abstract

The invention relates to a one-dimensional range profile simulation method based on space-time coding metasurface equivalent amplitude-phase synthesis. The method comprises the following steps: defining a modulation sequence of the space-time coding metasurface within the pulse duration of an incident radar signal, and obtaining a corresponding modulation echo according to the modulation sequence; equivalently expressing the modulated echo according to a stationary phase principle, and constructing an amplitude-phase fitting problem according to a system function of a false target generated by metasurface modulation in an equivalence formula; the amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of the HRRP, a space-time coding solving model is established according to the adjusted amplitude-phase fitting problem, the space-time coding solving model is solved in a nearest neighbor searching mode, and space-time coding is obtained; and modulating an incident radar signal according to designed space-time coding, and performing pulse compression processing on a modulated echo to present a false one-dimensional range profile of an expected target. By adopting the method, the target characteristic simulation precision and the modulation coding design efficiency can be improved.

Description

Technical Field

[0001] The present application relates to the field of radar intelligent jamming countermeasure technology, and in particular to a one-dimensional range profile simulation method based on time-space coding metasurface equivalent amplitude-phase synthesis. Background Art

[0002] Space-time coded metasurfaces have received extensive attention in the field of radar electronic countermeasures in recent years due to their advantages of low cost and flexible modulation. However, existing research on radar jamming technology based on metasurfaces focuses on the generation of false point target characteristics, which are quite different from the characteristics of real targets and are easily identified by broadband radars that can now measure the fine structure information of targets. In addition, the coordinated use of multiple metasurfaces will significantly increase the complexity of the system in practical applications, and the application scenario of a large area of ​​the metasurface conforming to the real target is difficult to achieve in practice. Therefore, more research has begun to focus on generating realistic radar target features based on a single metasurface. Limited by the limited number of modulation states of the metasurface, the target characteristic generation effect of existing research is greatly reduced due to the existence of quantization effect.

[0003] One solution to increase the number of metasurface modulation states is to use a metasurface with more bit encoding. However, it is very difficult to design a 3-bit or higher bit programmable metasurface based on PIN diodes in practice. Although continuous phase modulation can be achieved based on varactor diodes, it is often accompanied by high insertion loss and low modulation frequency. Some studies have introduced technologies such as liquid crystal and graphene into the design of continuous phase of metasurfaces, but the final phase accuracy is difficult to meet the requirements. Summary of the invention

[0004] Based on this, it is necessary to provide a one-dimensional range image simulation method based on space-time coding metasurface equivalent amplitude-phase synthesis, which can improve the target characteristic simulation accuracy and modulation coding design efficiency in response to the above technical problems.

[0005] A one-dimensional range image simulation method based on time-space coding metasurface equivalent amplitude-phase synthesis, the method comprising: Obtain the modulation model of the incident radar signal and the space-time coding metasurface radar signal, and derive the time domain equivalent amplitude and phase based on the modulation model of the space-time coding metasurface radar signal; calculate the frequency response of the radar target; define the modulation sequence of the space-time coding metasurface within the pulse duration of the incident radar signal, and obtain the corresponding modulated echo according to the modulation sequence; According to the stationary phase principle, the modulated echo is equivalently represented, and the system function of the false target is generated by the metasurface modulation in the equivalent formula. The amplitude-phase fitting problem is constructed by fitting the target frequency response based on the generated time-domain equivalent amplitude. The amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of HRRP to obtain the adjusted amplitude-phase fitting problem. A space-time coding solution model is established according to the adjusted amplitude-phase fitting problem, and the space-time coding solution model is solved by finding the nearest neighbor to obtain the space-time coding; the incident radar signal is modulated according to the designed space-time coding, and the modulated echo is processed by pulse compression to present a false one-dimensional range image of the expected target.

[0006] The above-mentioned one-dimensional range image simulation method based on space-time coding metasurface equivalent amplitude and phase synthesis, this application is based on the space-time coding metasurface radar signal modulation model, and derives the time domain equivalent amplitude and phase generation method; then the target frequency response is fitted based on the generated equivalent amplitude phase to determine the space-time coding sequence; finally, the space-time coding metasurface modulates the incident radar signal according to the designed space-time coding, and the modulated echo signal presents the expected target one-dimensional range image after pulse compression processing, making full use of the modulation freedom of the space-time coding metasurface in both time and space dimensions. Vector synthesis based on the spatial dimension realizes the equivalent amplitude and phase generation in the time dimension, thereby producing a better target HRRP simulation effect, and showing advantages in coding solution efficiency compared to existing solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a flowchart of a one-dimensional range image simulation method based on space-time coding metasurface equivalent amplitude-phase synthesis in one embodiment; Figure 2 is a schematic diagram of time domain equivalent amplitude and phase generation results under vertical incidence in one embodiment; Figure 2 (a) is the equivalent amplitude and phase generation result when the number of independently controllable column groups is 1; Figure 2 (b) is the equivalent amplitude and phase generation result when the number of independently controllable column groups is 5; Figure 2 (c) is the equivalent amplitude and phase generation result when the number of independently controllable column groups is 10; Figure 2 (d) is the equivalent amplitude and phase generation result when the number of independently controllable column groups is 20; Figure 3 FIG. 1 is a schematic diagram of a simulation result of a one-dimensional range profile of a target in one embodiment; Figure 3 (a1) is a comparison chart of the real one-dimensional range image under three scattering points, the best HRRP simulation result under the amplitude-phase fitting theory, the HRRP simulation result based on generating equivalent amplitude-phase, and the HRRP simulation result of the existing optimal solution; Figure 3 (b1) is the amplitude and phase fitting result based on generating equivalent amplitude and phase in the case of three scattering points; Figure 3 (c1) is the fitness curve of the existing optimal solution for solving modulation coding under the condition of 3 scattering points; Figure 3 (a2) is a comparison chart of the real one-dimensional range image under 6 scattering points, the best HRRP simulation result under the amplitude-phase fitting theory, the HRRP simulation result based on generating equivalent amplitude-phase, and the HRRP simulation result of the existing optimal solution; Figure 3 (b2) is the amplitude and phase fitting result based on generating equivalent amplitude and phase in the case of 6 scattering points; Figure 3 (c2) is the fitness curve of the existing optimal solution for solving modulation coding under the condition of 6 scattering points; Figure 3 (a3) is a comparison chart of the real one-dimensional range image under 9 scattering points, the best HRRP simulation result under the amplitude-phase fitting theory, the HRRP simulation result based on generating equivalent amplitude-phase, and the HRRP simulation result of the existing optimal solution; Figure 3 (b3) is the amplitude and phase fitting result based on generating equivalent amplitude and phase in the case of 9 scattering points; Figure 3 (c3) is the fitness curve of the existing optimal solution for solving modulation coding in the case of 9 scattering points. DETAILED DESCRIPTION

[0008] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0009] In one embodiment, Figure 1 As shown, a one-dimensional range image simulation method based on time-space coding metasurface equivalent amplitude-phase synthesis is provided, comprising the following steps: Step 102, obtain the incident radar signal and the modulation model of the space-time coded metasurface radar signal, derive the time domain equivalent amplitude and phase based on the modulation model of the space-time coded metasurface radar signal; calculate the frequency response of the radar target; define the modulation sequence of the space-time coded metasurface within the pulse duration of the incident radar signal, and obtain the corresponding modulated echo according to the modulation sequence.

[0010] This application is based on the time-space coding metasurface radar signal modulation model, and derives the time domain equivalent amplitude and phase generation method. First, consider a three-dimensional Cartesian coordinate system located at Planar space-time coding metasurface. An incident angle is Far-field radar signal For a single-station radar system, the modulated radar echo signal can be expressed as (1) in: and represent the elevation angle and azimuth angle respectively, Indicates fast time, and Represent the metasurface Axis and The number of elements in the axial direction, Indicates The coding unit is The reflection coefficient in the time interval is , represents the angular wave number corresponding to the center frequency, , represents the propagation speed of electromagnetic waves, and They represent the unit edges in the hypersurface Axis and The period length in the axial direction, , For the space-time coding hypersurface in The equivalent complex reflection coefficient in a time slot is the time domain equivalent amplitude phase. The first row and first column of the metasurface unit is used as a reference. The point scattering center model of the target is composed of several scattering points with specific amplitudes and positions. Based on this, the system function of the target can be expressed as a weighted superposition of a series of impulse functions, that is, (2) in, Indicates the number of scattering points of the target, Indicates The scattering intensity of each scattering point is Indicates The relative position between the scattering points and the radar, represents the impulse function.

[0011] Then the frequency response of the target can be expressed as (3) in, represents Fourier transform.

[0012] Through the modulation model of the radar signal based on the space-time coding metasurface, the modulation freedom of the two dimensions of time and space is fully utilized, and it is no longer limited to the previous single dimension or simple modulation method. The equivalent amplitude and phase generation of the time dimension is realized based on the vector synthesis of the space dimension, so that the final modulated echo signal can present the expected target one-dimensional range profile (HRRP) after pulse compression processing. The target characteristics generated in this way are closer to the characteristics of the real target, which is a significant improvement compared to the existing situation where more attention is paid to the generation of false point target characteristics and the gap with the real target characteristics is large.

[0013] Step 104, according to the stationary phase principle, the modulated echo is equivalently represented, and the system function of the false target is generated according to the super surface modulation in the equivalent formula, and the amplitude-phase fitting problem is constructed based on the generated time domain equivalent amplitude to the target frequency response. The amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of HRRP to obtain the adjusted amplitude-phase fitting problem.

[0014] Assuming that the radar transmits a broadband linear frequency modulation signal, its time domain expression is (4) in, represents the pulse width, Indicates the carrier frequency, Indicates the signal bandwidth.

[0015] Defined within the pulse duration of the incident radar signal, the modulation sequence of the space-time coding metasurface is Without loss of generality, let According to formula (1), the modulated echo can be expressed as (5) Based on the stationary phase principle, equation (5) can be equivalently expressed as (6) in, The system function representing the generation of false targets by metasurface modulation, represents the inverse Fourier transform, represents the frequency response of the metasurface modulation to generate false targets, .

[0016] Therefore, the target HRRP simulation based on the spatiotemporal coding metasurface essentially requires the realization of Towards is equivalent to right The amplitude-phase fitting problem is (7) in," "Indicates approach.

[0017] Since HRRP is amplitude sensitive, it focuses more on the relative size of the amplitude, so the problem is further transformed into (8) in, and Respectively represent the normalized , .

[0018] After deriving the time-domain equivalent amplitude and phase, the target frequency response is further fitted to construct an amplitude-phase fitting problem, and it is adjusted based on the amplitude sensitivity of HRRP. Then, the time-space coding solution model is established with the adjusted amplitude-phase fitting problem as the objective function, and the time-space coding is solved by finding the nearest neighbor. This complete adjustment process from amplitude-phase fitting to coding solution takes into account the key factors for generating a better target HRRP simulation effect. Compared with existing research that is limited by the limited number of modulation states of the metasurface and greatly reduced by the quantization effect, it can determine the appropriate coding more finely and accurately, thereby improving the target characteristic generation effect and reducing the adverse effects of the quantization effect on the final simulation effect.

[0019] Step 106, establish a space-time coding solution model according to the adjusted amplitude-phase fitting problem, solve the space-time coding solution model by finding the nearest neighbor, and obtain the space-time coding; modulate the incident radar signal according to the designed space-time coding, and the modulated echo is processed by pulse compression to present a false one-dimensional range image of the expected target.

[0020] A spatiotemporal coding solution model was established and solved by finding the nearest neighbor. Compared with existing solutions, this targeted model construction and solution method makes the coding determination process more efficient and orderly, avoiding the complex, cumbersome and inefficient coding design attempt process that may have existed in the past, thus showing advantages in coding solution efficiency, and being able to obtain the spatiotemporal coding that meets the requirements more quickly, thereby achieving effective modulation of the incident radar signal and improving the efficiency of the overall modulation coding design link.

[0021] The above-mentioned one-dimensional range image simulation method based on space-time coding metasurface equivalent amplitude and phase synthesis, this application is based on the space-time coding metasurface radar signal modulation model, and derives the time domain equivalent amplitude and phase generation method; then, the target frequency response is fitted based on the generated equivalent amplitude phase to determine the space-time coding sequence; finally, the space-time coding metasurface modulates the incident radar signal according to the designed space-time coding, and the modulated echo signal presents the expected target one-dimensional range image after pulse compression processing, making full use of the modulation freedom of the space-time coding metasurface in both time and space dimensions. Vector synthesis based on the spatial dimension realizes the equivalent amplitude and phase generation in the time dimension, thereby producing a better target HRRP simulation effect, and showing advantages in coding solution efficiency compared to existing solutions.

[0022] In one embodiment, the space-time coded metasurface radar signal modulation model is:

[0023] in: and represent the elevation angle and azimuth angle respectively, Indicates fast time, and Represent the metasurface Axis and The number of elements in the axial direction, Indicates The coding unit is The reflection coefficient in the time interval is , represents the angular wave number corresponding to the center frequency, , represents the propagation speed of electromagnetic waves, and They represent the unit edges in the hypersurface Axis and The period length in the axial direction, , For the space-time coding hypersurface in The equivalent complex reflection coefficient within a time slot is the time domain equivalent amplitude and phase generated.

[0024] In one embodiment, the process of calculating the frequency response of a radar target includes: The point scattering center model of the radar target is composed of a number of scattering points with specific amplitudes and positions. Based on this, the system function of the radar target can be expressed as a weighted superposition of a series of impulse functions, that is,

[0025] in, Indicates the number of scattering points of the radar target, Indicates The scattering intensity of each scattering point is Indicates The relative position between the scattering points and the radar, represents the impulse function.

[0026] Then the frequency response of the radar target can be expressed as

[0027] in, represents Fourier transform.

[0028] In one embodiment, obtaining a corresponding modulated echo according to a modulation sequence includes: According to the modulation sequence, the corresponding modulated echo is obtained as follows:

[0029] in, Indicates that the radar transmits a broadband linear frequency modulation signal, Modulation sequence, Indicates fast time, Indicates the time slot number, Represents the switching period of the metasurface modulation state.

[0030] In one embodiment, performing equivalent representation of the modulated echo according to the stationary phase principle includes: The equivalent formula for equivalently representing the modulated echo according to the stationary phase principle is:

[0031] in, The system function representing the generation of false targets by metasurface modulation, represents the inverse Fourier transform, represents the frequency response of the metasurface modulation to generate false targets, Modulation sequence, Indicates the time slot number, Indicates the carrier frequency, , represents the pulse width, represents the signal bandwidth, represents the switching period of the metasurface modulation state, Indicates frequency.

[0032] In one embodiment, the amplitude-phase fitting problem is constructed according to the system function of generating false targets by metasurface modulation in the equivalent formula, including: Targeted HRRP simulation based on spatiotemporal coding metasurfaces essentially requires the realization of Towards is equivalent to right The amplitude-phase fitting problem is

[0033] in," " means approaching, Indicates the time slot number, Modulation sequence, Indicates the time slot number, Indicates the carrier frequency, , represents the pulse width, represents the signal bandwidth, represents the switching period of the metasurface modulation state, Indicates frequency.

[0034] In one embodiment, the amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of the HRRP to obtain an adjusted amplitude-phase fitting problem, including: The amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of HRRP, and the adjusted amplitude-phase fitting problem is obtained as follows:

[0035] in, and Respectively represent the normalized , .

[0036] In one embodiment, a spatiotemporal coding solution model is established according to the adjusted amplitude-phase fitting problem, including: The time-space coding solution model is established based on the adjusted amplitude-phase fitting problem.

[0037] in, represents the L1 norm, express The feasible solution domain of Modulation sequence, Indicates the time slot number, Indicates the carrier frequency, , represents the pulse width, represents the signal bandwidth, represents the switching period of the metasurface modulation state, Indicates frequency.

[0038] In the specific embodiment, simulation experiments are used to verify the advantages of the present application. Figure 2 As shown in Figure 1, the equivalent amplitude and phase generation of a 20*20 2-bit space-time coding metasurface under vertical incidence is given. The metasurface units are divided into multiple independent controllable groups by column. Figure 2 The numbers of independently controllable groups corresponding to (a)-(d) are 1, 5, 10, and 20, respectively. Note that when the number of independently controllable groups is 1, it means that no spatial vector synthesis is performed. At this time, the number of equivalent amplitude and phase generated corresponds to the number of encoding bits of the metasurface. It can be seen that based on spatial vector synthesis, the number of modulation states of the metasurface increases significantly. Specifically, it increases from 4 to 36, 121, and 441, respectively, which verifies the effectiveness of the proposed equivalent amplitude and phase generation method. Figure 3 The simulation results of the target one-dimensional range image are given. The simulation parameters are set as: LFM signal, bandwidth MHz, pulse width us, carrier frequency GHz; the sampling rate is set to 1GHz; a 20*20 2-bit space-time coding metasurface is used, and the state switching frequency is 10MHz. Here, the metasurface is divided into 5 groups by column, and the units in each group have the same reflection coefficient in one modulation time slot. At this time, the generated equivalent amplitude is as follows Figure 2(b) Considering the case of vertical incidence, the target model uses the built-in random function in MATLAB to randomly select the position of the scattering center within the range of 10-20m, and the intensity of the scattering center within the range of 2-10. For the cases of 3, 6, and 9 scattering centers, the scattering center model of the target is obtained as follows: , , , , , The actual target HRRP results are as follows: Figure 3 (a1)-(a3) True Value. In order to verify the correctness of the proposed amplitude-phase fitting method in simulating the target HRRP, we first consider , that is, the feasible domain is the entire complex domain, and finally the theoretically optimal result of the proposed method is obtained, such as Figure 3 (a1)-(a3) Optimal Value. Figure 3 By comparing the True Value and Optimal Value in (a1)-(a3), we can find that the results of the two are very consistent, which verifies the theoretical correctness of the proposed scheme. Further, consider the hardware constraints of the space-time coding metasurface. Figure 2 The fitting results of the target frequency response in the feasible domain in (b) are as follows: Figure 3 (b1)-(b3) As shown. It can be seen that although the trend of change is well fitted, due to the limited number of equivalent amplitude and phase, there is still a certain error in the amplitude and phase fitting, which ultimately leads to a small difference between the proposed value and the True Value in the sidelobe structure of the actual simulation effect of the proposed method. However, overall, the proposed scheme still maintains a high degree of similarity under the three target scattering center distribution conditions, as shown in Figure 3 (a1)-(a3) Proposed Value. Figure 3 (a1)-(a3) SOTA Value shows the existing HRRP simulation results based on iterative optimization scheme. Although it can keep consistent with the true value in the distribution of strong scattering and peak, it has significant differences with the true value in the weak scattering peak and sidelobe structure. In addition, Figure 3(c1)-(c3) show the iterative process of the existing scheme in solving the modulation coding. If the first time the maximum fitness function value is reached is the termination time, the time consumption in the three cases is approximately 76.60s, 99.51s, and 100.3s respectively. The scheme based on amplitude-phase fitting uses the feasible domain numerical generation and the nearest neighbor method to achieve the optimal solution, and the time consumption is only 0.007834s. Therefore, the proposed HRRP simulation scheme based on amplitude-phase fitting is significantly better than the existing scheme in terms of accuracy and solution efficiency.

[0039] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0040] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0041] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A one-dimensional range image simulation method based on time-space coding metasurface equivalent amplitude-phase synthesis, characterized in that: The method comprises: Acquire the modulation model of the incident radar signal and the space-time coding metasurface radar signal, and derive the time domain equivalent amplitude and phase based on the modulation model of the space-time coding metasurface radar signal; calculate the frequency response of the radar target; define the modulation sequence of the space-time coding metasurface within the pulse duration of the incident radar signal, and obtain the corresponding modulated echo according to the modulation sequence; The modulated echo is equivalently represented according to the stationary phase principle, and the system function of the false target is generated by the super surface modulation in the equivalent formula. The amplitude-phase fitting problem is constructed by fitting the target frequency response based on the generated time-domain equivalent amplitude; the amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of HRRP to obtain the adjusted amplitude-phase fitting problem; A space-time coding solution model is established according to the adjusted amplitude-phase fitting problem, and the space-time coding solution model is solved by finding the nearest neighbor to obtain the space-time coding; the incident radar signal is modulated according to the designed space-time coding, and the modulated echo is processed by pulse compression to present a false one-dimensional range image of the expected target.

2. The method according to claim 1, characterized in that The modulation model of the space-time coded metasurface radar signal is: in: and represent the elevation angle and azimuth angle respectively, Indicates fast time, and Represent the metasurface Axis and The number of elements in the axial direction, Indicates The coding unit is The reflection coefficient in the time interval is , represents the angular wave number corresponding to the center frequency, , represents the propagation speed of electromagnetic waves, and They represent the unit edges in the hypersurface Axis and The period length in the axial direction, , For the space-time coding hypersurface in The equivalent complex reflection coefficient within a time slot is the time domain equivalent amplitude and phase generated.

3. The method according to claim 1, characterized in that The process of calculating the frequency response of a radar target involves: The point scattering center model of the radar target is composed of a number of scattering points with specific amplitudes and positions. Based on this, the system function of the radar target can be expressed as a weighted superposition of a series of impulse functions, that is, in, Indicates the number of scattering points of the radar target, Indicates The scattering intensity of each scattering point is Indicates The relative position between the scattering points and the radar, represents the impulse function. Then the frequency response of the radar target can be expressed as in, represents Fourier transform.

4. The method according to claim 1, characterized in that Obtaining a corresponding modulated echo according to the modulation sequence includes: The corresponding modulated echo obtained according to the modulation sequence is: in, Indicates that the radar transmits a broadband linear frequency modulation signal, Modulation sequence, Indicates fast time, Indicates the time slot number, Represents the switching period of the metasurface modulation state.

5. The method according to claim 1, characterized in that The modulated echo is equivalently represented according to the stationary phase principle, including: The equivalent formula for equivalently representing the modulated echo according to the stationary phase principle is: in, The system function representing the generation of false targets by metasurface modulation, represents the inverse Fourier transform, represents the frequency response of the metasurface modulation to generate false targets, Modulation sequence, Indicates the time slot number, Indicates the carrier frequency, , represents the pulse width, represents the signal bandwidth, represents the switching period of the metasurface modulation state, Indicates frequency.

6. The method according to claim 1, characterized in that According to the system function of the metasurface modulation to generate false targets in the equivalent formula, the amplitude-phase fitting problem is constructed, including: Targeted HRRP simulation based on spatiotemporal coding metasurfaces essentially requires the realization of Towards is equivalent to right The amplitude-phase fitting problem is in," " means approaching, Indicates the time slot number, Modulation sequence, Indicates the time slot number, Indicates the carrier frequency, , represents the pulse width, represents the signal bandwidth, represents the switching period of the metasurface modulation state, Indicates frequency.

7. The method according to claim 6, characterized in that The amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of HRRP to obtain an adjusted amplitude-phase fitting problem, including: The amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of HRRP, and the adjusted amplitude-phase fitting problem is obtained as follows: in, and Respectively represent the normalized , .

8. The method according to claim 1, characterized in that A time-space coding solution model is established according to the adjusted amplitude-phase fitting problem, including: According to the adjusted amplitude-phase fitting problem, a time-space coding solution model is established: in, represents the L1 norm, express The feasible solution domain of Modulation sequence, Indicates the time slot number, Indicates the carrier frequency, , represents the pulse width, represents the signal bandwidth, represents the switching period of the metasurface modulation state, Indicates frequency.

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