One-dimensional range image simulation method based on spatiotemporal coding metasurface equivalent amplitude-phase synthesis

Abstract

This application relates to a one-dimensional range image simulation method based on equivalent amplitude-phase synthesis using a spatiotemporally coded metasurface. The method includes: defining a modulation sequence of a spatiotemporally coded metasurface within the pulse duration of an incident radar signal; obtaining the corresponding modulated echo based on the modulation sequence; performing an equivalent representation of the modulated echo according to the stationary phase principle; constructing an amplitude-phase fitting problem based on the system function of the metasurface modulation generating a false target in the equivalent formula; adjusting the amplitude-phase fitting problem based on the amplitude sensitivity of HRRP; establishing a spatiotemporally coded solution model based on the adjusted amplitude-phase fitting problem; solving the spatiotemporally coded solution model by finding the nearest neighbor to obtain the spatiotemporal code; modulating the incident radar signal according to the designed spatiotemporal code; and then performing pulse compression processing on the modulated echo to present a false one-dimensional range image of the expected target. This method can improve the accuracy of target characteristic simulation and the efficiency of modulation coding design.

Description

Technical Field

[0001] This application relates to the field of radar intelligent jamming countermeasures technology, and in particular to a one-dimensional range image simulation method based on spatiotemporally coded metasurface equivalent amplitude-phase synthesis. Background Technology

[0002] Spatiotemporally coded metasurfaces have gained widespread attention in radar electronic countermeasures in recent years due to their advantages of low cost and flexible modulation. However, existing research on metasurface-based radar jamming techniques largely focuses on generating false point target characteristics, which differ significantly from real target characteristics and are easily identified by broadband radars capable of measuring fine target structure information. Furthermore, the collaborative use of multiple metasurfaces significantly increases system complexity in practical applications, and the application scenario of large-area conformal metasurfaces to real targets is difficult to achieve in practice. Therefore, more research is beginning to focus on generating realistic radar target features based on a single metasurface. Limited by the finite number of modulation states of the metasurface, the target characteristic generation effect of existing research is significantly reduced due to quantization effects.

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

[0004] Therefore, it is necessary to provide a one-dimensional range image simulation method based on the equivalent amplitude-phase synthesis of spatiotemporal coded metasurfaces, which can improve the accuracy of target characteristic simulation and the efficiency of modulation and coding design, in order to address the above-mentioned technical problems.

[0005] A one-dimensional range image simulation method based on spatiotemporally coded metasurface equivalent amplitude-phase synthesis, the method comprising:

[0006] The modulation models of the incident radar signal and the spatiotemporally coded metasurface radar signal are obtained. The equivalent amplitude and phase in the time domain are derived based on the modulation model of the spatiotemporally coded metasurface radar signal. The frequency response of the radar target is calculated. The modulation sequence of the spatiotemporally coded metasurface within the pulse duration of the incident radar signal is defined, and the corresponding modulation echo is obtained according to the modulation sequence.

[0007] The modulated echo is equivalently represented based on the stationary phase principle. Based on the system function of the metasurface modulation generating the false target in the equivalent formula, the amplitude-phase fitting problem is constructed by fitting the generated time-domain equivalent amplitude relative 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.

[0008] A spatiotemporal coding solution model is established based on the adjusted amplitude-phase fitting problem. The spatiotemporal coding solution model is solved by finding the nearest neighbor to obtain the spatiotemporal code. The incident radar signal is modulated according to the designed spatiotemporal code. The modulated echo is processed by pulse compression to present a false one-dimensional range image of the expected target.

[0009] The aforementioned one-dimensional range profile simulation method based on equivalent amplitude-phase synthesis using a spatiotemporally coded metasurface derives a temporal equivalent amplitude-phase generation method from a radar signal modulation model using a spatiotemporally coded metasurface. Then, the generated equivalent amplitude-phase is fitted to the target frequency response to determine the spatiotemporally coded sequence. Finally, the spatiotemporally coded metasurface modulates the incident radar signal according to the designed spatiotemporal code. The modulated echo signal, after pulse compression processing, presents the expected one-dimensional range profile of the target, fully utilizing the modulation degrees of freedom in both time and space dimensions of the spatiotemporally coded metasurface. Vector synthesis based on the spatial dimension achieves equivalent amplitude-phase generation in the temporal dimension, resulting in superior target HRRP simulation effects and demonstrating advantages in coding solution efficiency compared to existing schemes. Attached Figure Description

[0010] Figure 1 This is a flowchart illustrating a one-dimensional range image simulation method based on spatiotemporally coded metasurface equivalent amplitude-phase synthesis in one embodiment.

[0011] Figure 2 This is a schematic diagram of the time-domain equivalent amplitude-phase generation result under perpendicular incidence conditions in one embodiment; Figure 2 (a) is the equivalent amplitude phase generation result when the number of independent controllable column groups is 1; Figure 2 (b) is the equivalent amplitude phase generation result when the number of independent controllable column groups is 5; Figure 2 (c) is the equivalent amplitude phase generation result when the number of independent controllable column groups is 10; Figure 2 (d) is the equivalent amplitude phase generation result when the number of independent controllable column groups is 20;

[0012] Figure 3 This is a schematic diagram of the simulation result of a one-dimensional distance image of the target in one embodiment; Figure 3 (a1) is a comparison of the actual one-dimensional range image, 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 scheme under the condition of 3 scattering points; Figure 3(b1) shows the amplitude and phase fitting results based on the generated equivalent amplitude and phase in the case of 3 scattering points; Figure 3 (c1) is the fitness curve of the existing optimal solution for modulation coding under the condition of 3 scattering points; Figure 3 (a2) is a comparison of the actual one-dimensional range image, the best HRRP simulation results under the amplitude-phase fitting theory, the HRRP simulation results based on generating equivalent amplitude-phase, and the HRRP simulation results of the existing optimal scheme under the condition of 6 scattering points; Figure 3 (b2) shows the amplitude and phase fitting results based on the generated equivalent amplitude and phase in the case of 6 scattering points; Figure 3 (c2) is the fitness curve of the existing optimal scheme for solving modulation and coding under the condition of 6 scattering points; Figure 3 (a3) is a comparison of the actual one-dimensional range image, the best HRRP simulation results under the amplitude-phase fitting theory, the HRRP simulation results based on generating equivalent amplitude-phase, and the HRRP simulation results of the existing optimal scheme under the condition of 9 scattering points; Figure 3 (b3) shows the amplitude and phase fitting results based on the generated equivalent amplitude and phase in the case of 9 scattering points; Figure 3 (c3) is the fitness curve of the existing optimal scheme for solving modulation coding under the condition of 9 scattering points. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0014] In one embodiment, such as Figure 1 As shown, a one-dimensional range image simulation method based on spatiotemporally encoded metasurface equivalent amplitude-phase synthesis is provided, including the following steps:

[0015] Step 102: Obtain the modulation model of the incident radar signal and the spatiotemporally coded metasurface radar signal; derive the time-domain equivalent amplitude and phase based on the spatiotemporally coded metasurface radar signal modulation model; calculate the frequency response of the radar target; define the modulation sequence of the spatiotemporally coded metasurface within the pulse duration of the incident radar signal; and obtain the corresponding modulation echo based on the modulation sequence.

[0016] This application derives a time-domain equivalent amplitude and phase generation method based on a spatiotemporally coded metasurface radar signal modulation model. First, it considers a signal located in a three-dimensional Cartesian coordinate system... A planar spatiotemporally encoded metasurface. An incident angle is... Far-field radar signals Incident on the metasurface. For a monostatic radar system, the modulated radar echo signal can be expressed as...

[0017] (1)

[0018] in: and These represent pitch and azimuth angles, respectively. Indicates a fast time. and Representing the metasurface along shaft and Number of elements in the axial direction, Indicates the first The coding unit in the first Reflection coefficient over a time interval , The angular wavenumber represents the center frequency. , Indicates the speed of propagation of electromagnetic waves. and Representing the elements along the metasurface shaft and Period length in the axial direction, , For spatiotemporally encoded metasurfaces in the first The equivalent complex reflection coefficient within each time slot, i.e., the generated temporal equivalent amplitude and phase. The metasurface unit in the first row and first column is used as a reference. The target's point scattering center model consists of several scattering points with specific amplitudes and positions. Based on this, the target's system function can be expressed as a weighted superposition of a series of impulse functions, i.e.

[0019] (2)

[0020] in, Indicates the number of scattering points from the target. Indicates the first The scattering intensity at each scattering point Indicates the first The relative positions of the scattering points and the radar This represents the impulse function.

[0021] The target's frequency response can then be expressed as

[0022] (3)

[0023] in, This represents the Fourier transform.

[0024] By employing a temporal-coded metasurface radar signal modulation model, the modulation freedom of both time and space is fully utilized, moving beyond the limitations of previous single-dimensional or simple modulation methods. Vector synthesis based on the spatial dimension enables equivalent amplitude and phase generation in the temporal dimension. This allows the final modulated echo signal, after pulse compression processing, to present the expected one-dimensional target range profile (HRRP). The generated target features more closely resemble those of the real target, representing a significant improvement over existing methods that focus on generating false target characteristics that deviate considerably from the true target characteristics.

[0025] Step 104: Based on the stationary phase principle, the modulated echo is represented equivalently. Based on the system function of the metasurface modulation generating the false target in the equivalent formula, the amplitude-phase fitting problem is constructed by fitting the generated time-domain equivalent amplitude relative 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.

[0026] Assuming the radar transmits a broadband linear frequency modulated signal, its time-domain expression is:

[0027] (4)

[0028] in, Indicates the pulse width. Indicates the carrier frequency. This indicates the signal bandwidth.

[0029] The modulation sequence of the spatiotemporally coded metasurface is defined as follows within the pulse duration of the incident radar signal: Without loss of generality, From equation (1), the modulated echo can be expressed as:

[0030] (5)

[0031] Based on the principle of stationary phase, equation (5) can be equivalently expressed as:

[0032] (6)

[0033] in, This represents the system function for generating spurious targets through metasurface modulation. Indicates the inverse Fourier transform. This represents the frequency response of the spurious target generated by metasurface modulation. .

[0034] Therefore, target HRRP simulation based on spatiotemporally encoded metasurfaces essentially needs to achieve... Towards The approximation is equivalent to right The amplitude-phase fitting problem, i.e.

[0035] (7)

[0036] in," "" indicates approaching.

[0037] Because HRRP is amplitude-sensitive, it focuses more on the relative magnitude of the amplitude, thus the problem further transforms into

[0038] (8)

[0039] in, and They represent the normalized values ​​respectively. , .

[0040] After deriving the time-domain equivalent amplitude and phase, an amplitude-phase fitting problem is further constructed by fitting the target frequency response. This problem is then adjusted based on the amplitude sensitivity of HRRP. Finally, a spatiotemporal coding solution model is established using the adjusted amplitude-phase fitting problem as the objective function, and the spatiotemporal code is obtained by finding the nearest neighbor. This entire adjustment process, from amplitude-phase fitting to coding solution, considers all key factors in generating better target HRRP simulation results. Compared to existing research, which is significantly compromised by quantization effects due to the limited number of modulation states on the metasurface, this approach can more precisely and accurately determine the appropriate coding, thereby improving the generation of target characteristics and reducing the adverse effects of quantization on the final simulation results.

[0041] Step 106: Establish a spatiotemporal coding solution model based on the adjusted amplitude-phase fitting problem, solve the spatiotemporal coding solution model by finding the nearest neighbor, and obtain the spatiotemporal code; modulate the incident radar signal according to the designed spatiotemporal code, and the modulated echo is processed by pulse compression to present a false one-dimensional range image of the expected target.

[0042] A spatiotemporal coding solution model was established and solved using the nearest neighbor method. Compared with existing schemes, this targeted model construction and solution method makes the coding determination process more efficient and orderly, avoiding the complex, tedious, and inefficient coding design trial process that may have existed in the past. Thus, it shows an advantage in coding solution efficiency, and can obtain the required spatiotemporal code more quickly, thereby realizing the effective modulation of the incident radar signal and improving the efficiency of the overall modulation and coding design process.

[0043] The aforementioned one-dimensional range profile simulation method based on equivalent amplitude-phase synthesis using a spatiotemporally coded metasurface derives a temporal equivalent amplitude-phase generation method from a radar signal modulation model using a spatiotemporally coded metasurface. Subsequently, the generated equivalent amplitude-phase is fitted to the target frequency response to determine the spatiotemporally coded sequence. Finally, the spatiotemporally coded metasurface modulates the incident radar signal according to the designed spatiotemporal code. The modulated echo signal, after pulse compression processing, presents the expected one-dimensional range profile of the target, fully utilizing the modulation degrees of freedom in both time and space dimensions of the spatiotemporally coded metasurface. Vector synthesis based on the spatial dimension achieves equivalent amplitude-phase generation in the temporal dimension, resulting in superior target HRRP simulation performance and demonstrating advantages in coding solution efficiency compared to existing schemes.

[0044] In one embodiment, the spatiotemporal coded metasurface radar signal modulation model is as follows:

[0045]

[0046] in: and These represent pitch and azimuth angles, respectively. Indicates a fast time. and Representing the metasurface along shaft and Number of elements in the axial direction, Indicates the first The coding unit in the first Reflection coefficient over a time interval , The angular wavenumber represents the center frequency. , Indicates the speed of propagation of electromagnetic waves. and Representing the elements along the metasurface shaft and Period length in the axial direction, , For spatiotemporally encoded metasurfaces in the first The equivalent complex reflection coefficient within each time slot, i.e. the generated time-domain equivalent amplitude and phase.

[0047] In one embodiment, the process of calculating the frequency response of a radar target includes:

[0048] The point scattering center model of a radar target consists of several 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, i.e.

[0049]

[0050] in, This indicates the number of scattering points of a radar target. Indicates the first The scattering intensity at each scattering point Indicates the first The relative positions of the scattering points and the radar This represents the impulse function.

[0051] The frequency response of a radar target can then be expressed as:

[0052]

[0053] in, This represents the Fourier transform.

[0054] In one embodiment, obtaining the corresponding modulation echo based on the modulation sequence includes:

[0055] The corresponding modulation echo is obtained based on the modulation sequence.

[0056]

[0057] in, This indicates that the radar is transmitting a broadband linear frequency modulated signal. Modulation sequence, Indicates a fast time. Indicates the time slot number, This indicates the switching period of the metasurface modulation state.

[0058] In one embodiment, the modulated echo is equivalently represented according to the stationary phase principle, including:

[0059] The equivalent formula for representing the modulated echo based on the stationary phase principle is as follows:

[0060]

[0061] in, This represents the system function for generating spurious targets through metasurface modulation. Indicates the inverse Fourier transform. This represents the frequency response of the spurious target generated by metasurface modulation. Modulation sequence, Indicates the time slot number, Indicates the carrier frequency. , Indicates the pulse width. Indicates signal bandwidth. Indicates the switching period of the metasurface modulation state. Indicates frequency.

[0062] In one embodiment, the amplitude-phase fitting problem is constructed based on the system function for generating spurious targets using metasurface modulation in the equivalent formula, including:

[0063] HRRP simulation of targets based on spatiotemporally encoded metasurfaces essentially needs to achieve... Towards The approximation is equivalent to right The amplitude-phase fitting problem, i.e.

[0064]

[0065] in," "Indicates approaching" Indicates the time slot number, Modulation sequence, Indicates the time slot number, Indicates the carrier frequency. , Indicates the pulse width. Indicates signal bandwidth. Indicates the switching period of the metasurface modulation state. Indicates frequency.

[0066] In one embodiment, the amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of HRRP to obtain an adjusted amplitude-phase fitting problem, including:

[0067] The amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of HRRP, resulting in the adjusted amplitude-phase fitting problem as follows:

[0068]

[0069] in, and They represent the normalized values ​​respectively. , .

[0070] In one embodiment, a spatiotemporal coding solution model is established based on the adjusted amplitude-phase fitting problem, including:

[0071] A spatiotemporal coding solution model is established based on the adjusted amplitude-phase fitting problem.

[0072]

[0073] in, Describing the L1 norm, express The feasible solution domain. Modulation sequence, Indicates the time slot number, Indicates the carrier frequency. , Indicates the pulse width. Indicates signal bandwidth. Indicates the switching period of the metasurface modulation state. Indicates frequency.

[0074] In a specific embodiment, simulation experiments are used to verify the advantages of this application. For example... Figure 2 As shown, the equivalent amplitude-phase generation of a 20*20 2-bit spatiotemporally encoded metasurface under perpendicular incidence is presented. The metasurface units are divided into multiple independent controllable groups by columns. Figure 2 The number of independent controllable groups corresponding to (a)-(d) are 1, 5, 10, and 20, respectively. Note that when the number of independent controllable groups is 1, it means that no spatial vector synthesis was performed, and the number of equivalent amplitude-phase generated corresponds to the number of encoded 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, verifying the effectiveness of the proposed equivalent amplitude-phase generation method. Figure 3 Simulation results of a one-dimensional range profile of the target are presented. Simulation parameters are set as follows: LFM signal, bandwidth... MHz, pulse width us, carrier frequency GHz; sampling rate set to 1 GHz; using a 20*20 2-bit spatiotemporal coded metasurface, with a state switching frequency of 10 MHz, the metasurface is divided into 5 groups by columns, and the units within each group have the same reflection coefficient within a modulation time slot. The resulting equivalent amplitude is as follows: Figure 2 As shown in (b); considering the case of perpendicular incidence; the target model uses a built-in random function in MATLAB to randomly select the location of the scattering center within the range of 10-20m, and randomly select the intensity of the scattering center within the range of 2-10. For the three cases of 3, 6, and 9 scattering centers, the target scattering center model is obtained as follows. , , , , , The actual target HRRP results are as follows: Figure 3 The True Values ​​(a1)-(a3) are shown. To verify the correctness of the proposed amplitude-phase fitting method on the simulated target HRRP, we first consider... This considers the case where the feasible region is the entire complex field, ultimately yielding the theoretically optimal result of the proposed method, such as... Figure 3 The Optimal Values ​​(a1)-(a3) are shown below. Figure 3A comparison of the True Value and Optimal Value in (a1)-(a3) reveals a strong agreement, validating the theoretical correctness of the proposed scheme. Furthermore, the hardware constraints of the spatiotemporally coded metasurface are considered. Based on... Figure 2 The fitting results of the target frequency response in the feasible region in (b) are as follows: Figure 3 As shown in (b1)-(b3), although the trend is well fitted, the limited number of equivalent amplitude phases results in some error in amplitude phase fitting. This ultimately leads to a slight difference between the Proposed Value and True Value in the actual simulation results. However, overall, the proposed scheme maintains a high degree of similarity under the three target scattering center distributions, such as... Figure 3 The Proposed Values ​​(a1)-(a3) are shown below. Figure 3 (a1)-(a3) SOTA Values ​​demonstrate existing HRRP simulation results based on iterative optimization schemes. While they maintain consistency with the true values ​​in the distribution of strong scattering and peaks, they exhibit significant differences in the weak scattering peaks and sidelobe structure. Furthermore, Figure 3 (c1)-(c3) show the iterative process of the existing scheme in solving the modulation and coding problem. If the termination time is the initial attainment of the maximum fitness function value, the time taken in the three cases is approximately 76.60s, 99.51s, and 100.3s, respectively. In contrast, the scheme based on amplitude-phase fitting uses the feasible region numerical generation and nearest neighbor method to achieve the optimal solution, taking only 0.007834s. Therefore, the proposed HRRP simulation scheme based on amplitude-phase fitting significantly outperforms the existing schemes in both accuracy and solution efficiency.

[0075] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed 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 some of the sub-steps or stages of other steps.

[0076] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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.

[0077] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A one-dimensional range image simulation method based on spatiotemporally coded metasurface equivalent amplitude-phase synthesis, characterized in that, The method includes: The modulation model of the incident radar signal and the spatiotemporally coded metasurface radar signal is obtained, and the time-domain equivalent amplitude and phase are derived based on the spatiotemporally coded metasurface radar signal modulation model; the frequency response of the radar target is calculated; the modulation sequence of the spatiotemporally coded metasurface within the pulse duration of the incident radar signal is defined, and the corresponding modulation echo is obtained according to the modulation sequence; The modulated echo is equivalently represented according to the stationary phase principle. Based on the system function of the metasurface modulation generating the false target in the equivalent formula, the amplitude-phase fitting problem is constructed by fitting the generated time-domain equivalent amplitude relative 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. A spatiotemporal coding solution model is established based on the adjusted amplitude-phase fitting problem. The spatiotemporal coding solution model is solved by finding the nearest neighbor to obtain the spatiotemporal code. The incident radar signal is modulated according to the designed spatiotemporal code. The modulated echo is processed by pulse compression to present a false one-dimensional range image of the expected target. The spatiotemporal coded metasurface radar signal modulation model is as follows: in: and These represent pitch and azimuth angles, respectively. Indicates a fast time. and Representing the metasurface along shaft and Number of elements in the axial direction, Indicates the first The coding unit in the first Reflection coefficient over a time interval Indicates far-field radar signal, , The angular wavenumber represents the center frequency. , Indicates the speed of propagation of electromagnetic waves. and Representing the elements along the metasurface shaft and Period length in the axial direction, , For spatiotemporally encoded metasurfaces in the first The equivalent complex reflection coefficient within each time slot, i.e., the generated time-domain equivalent amplitude and phase. This indicates the switching period of the metasurface modulation state.

2. The method according to claim 1, characterized in that, The process of calculating the frequency response of a radar target includes: The point scattering center model of a radar target consists of several scattering points with specific amplitudes and locations. Based on this, the system function of the radar target can be expressed as a weighted superposition of a series of impulse functions, i.e.: in, This indicates the number of scattering points of a radar target. Indicates the first The scattering intensity at each scattering point Indicates the first The relative positions of the scattering points and the radar Represents the impact function; The frequency response of a radar target can then be expressed as: in, This represents the Fourier transform.

3. The method according to claim 1, characterized in that, Obtaining the corresponding modulation echo based on the modulation sequence includes: The corresponding modulation echo obtained from the modulation sequence is: in, This indicates that the radar is transmitting a broadband linear frequency modulated signal. Modulation sequence, Indicates a fast time. Indicates the time slot number, This indicates the switching period of the metasurface modulation state.

4. The method according to claim 3, characterized in that, The modulated echo is equivalently represented according to the stationary phase principle, including: The equivalent formula for representing the modulated echo based on the stationary phase principle is as follows: in, This represents the system function for generating spurious targets through metasurface modulation. Indicates the inverse Fourier transform. This represents the frequency response of the spurious target generated by metasurface modulation. Modulation sequence, Indicates the time slot number, Indicates the carrier frequency. , Indicates the pulse width. Indicates signal bandwidth. Indicates the switching period of the metasurface modulation state. Indicates frequency.

5. The method according to claim 1, characterized in that, Based on the system function of metasurface modulation for generating spurious targets in the equivalent formula, an amplitude-phase fitting problem is constructed, including: HRRP simulation of targets based on spatiotemporally encoded metasurfaces essentially needs to achieve... Towards The approximation is equivalent to right The amplitude-phase fitting problem, namely: in," "Indicates approaching" Indicates the time slot number, Modulation sequence, Indicates the time slot number, Indicates the carrier frequency. , Indicates the pulse width. Indicates signal bandwidth. Indicates the switching period of the metasurface modulation state. Indicates frequency.

6. The method according to claim 5, characterized in that, The amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of HRRP to obtain the adjusted amplitude-phase fitting problem, including: The amplitude-phase fitting problem is adjusted based on the amplitude sensitivity of HRRP, resulting in the adjusted amplitude-phase fitting problem as follows: in, and They represent the normalized values ​​respectively. , .

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

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