High-resolution range profile simulation method based on segmented periodic modulation signal

Abstract

The invention relates to a high-resolution range profile simulation method based on segmented periodic modulation signals. The method comprises the following steps: extracting target feature information of a one-dimensional high-resolution range profile of a to-be-simulated target, determining modulation parameters of a segmented periodic modulation signal according to the target feature information, generating the segmented periodic modulation signal based on the determined modulation parameters, modulating an incident signal of a phase modulation surface by using the segmented periodic modulation signal, and generating a phase modulation signal. And performing pulse compression processing on the echo signal modulated by the phase modulation surface to obtain a simulated one-dimensional high-resolution range profile of the target echo signal. By adopting the method, the realistic simulation of the target HRRP can be realized.

Description

Technical Field

[0001] This application relates to the technical field of radar signal processing, and particularly to a method for simulating high-resolution range profiles based on piecewise periodic modulation signals. Background Art

[0002] One-dimensional high-resolution range profile (HRRP) is the distribution of target scattering centers along the radar line of sight, which contains rich structural information such as target size and scatterer intensity, and is an important feature for radar target recognition. Radar target feature simulation technology can generate false features similar to real targets, effectively preventing the acquisition of real target information, and is one of the current important research directions.

[0003] In recent years, the emergence and development of electromagnetic modulation metamaterials have provided a new idea for simulating target HRRP. By precisely regulating the parameters of the incident wave in real time, the characteristic modulation of HRRP can be achieved, and it has the advantages of rapid response and low cost.

[0004] Existing research on target HRRP simulation is mainly based on active frequency selective surface (AFSS) and phase switched screen (PSS). Through time-domain periodic modulation of the incident signal, a series of discrete peaks are generated in the range dimension. However, the false scatterers generated by these modulation methods are symmetrically and equally spaced about the center position of the metasurface, which is inconsistent with the complex structure of real targets and is easily recognized by broadband radar systems. Aiming at the deficiencies of the current HRRP simulation method, the present invention designs a piecewise periodic modulation signal based on a phase modulation metasurface, and designs the modulation parameters of the signal based on the HRRP characteristics of the target, which can achieve a realistic simulation of the target HRRP. Summary of the Invention

[0005] Based on this, it is necessary to provide a method for simulating high-resolution range profiles based on piecewise periodic modulation signals that can realistically simulate target HRRP for the above technical problems.

[0006] A method for simulating high-resolution range profiles based on piecewise periodic modulation signals, the method comprising: Obtain the target echo signal to be simulated, and extract target feature information according to the one-dimensional high-resolution range profile of the target echo signal; Determine the modulation parameters of the piecewise periodic modulation signal according to the target feature information, and generate a piecewise periodic modulation signal based on the determined modulation parameters; Modulate the incident signal on the phase modulation surface by using the segmented periodic modulation signal to obtain the echo signal modulated by the phase modulation surface; Perform pulse compression processing on the echo signal modulated by the phase modulation surface to obtain the simulated one-dimensional high-resolution range profile of the target echo signal. In one embodiment, the number of discrete peaks, the position of each discrete peak, and the amplitude are extracted from the one-dimensional high-resolution range profile of the target echo signal, and the number of discrete peaks, the positions and amplitudes of the discrete peaks are used as the target feature information.

[0007] In one embodiment, the modulation parameters include: the number of segments of the segmented periodic modulation signal, the modulation frequency, the duty cycle, and the duration.

[0008] In one embodiment, determining the modulation parameters of the segmented periodic modulation signal according to the target feature information includes: Determine the number of segments according to the number of discrete peaks in the one-dimensional high-resolution range profile; Determine the modulation frequency by aligning the positions of the -1 order false targets in each subsequence of the segmented periodic modulation signal with the positions of the corresponding target scatter points in the one-dimensional high-resolution range profile; Determine the duration by aligning the normalized amplitudes of the -1 order false targets in each subsequence of the segmented periodic modulation signal with the normalized amplitudes of the corresponding target scatter points in the one-dimensional high-resolution range profile.

[0009] In one embodiment, the duty cycle is set to 0.5.

[0010] In one embodiment, to determine the modulation frequency, the following formula is used: ; In the above formula, represents the modulation frequency of the th subsequence, represents the frequency modulation slope of the linear frequency modulation signal, represents the speed of light, represents the distance between the th peak of the target and the radar, is the distance between the phase modulation surface and the radar.

[0011] In one embodiment, to determine the duration, the following formula is used: ; In the above formula, represents the duration of the th subsequence, represents the scattering intensity of the th peak of the target, Indicates the pulse width of the chirp signal.

[0012] The above-mentioned high-resolution range profile simulation method based on the segmented periodic modulation signal extracts the target feature information of the one-dimensional high-resolution range profile of the target to be simulated, determines the modulation parameters of the segmented periodic modulation signal according to the target feature information, generates the segmented periodic modulation signal based on the determined modulation parameters, modulates the incident signal on the phase modulation surface with the segmented periodic modulation signal to obtain the echo signal modulated by the phase modulation surface, and performs pulse compression processing on the echo signal modulated by the phase modulation surface to obtain the simulated one-dimensional high-resolution range profile of the target echo signal. Compared with the traditional periodic modulation signal, the designed segmented periodic modulation signal of this method can generate a series of irregularly distributed false images, and the modulation pattern is more flexible and changeable. This method extracts the number, position and amplitude of the target HRRP peaks, and can realize the realistic simulation of the target HRRP based on a single phase modulation surface, with the advantages of high cost performance and simple parameter calculation. Description of the Drawings

[0013] Figure 1 Is a schematic flow chart of the high-resolution range profile simulation method based on the segmented periodic modulation signal in one embodiment; Figure 2 Is a schematic time-domain diagram of the segmented periodic modulation signal in one embodiment; Figure 3 Is a schematic diagram of the simulation experiment results of the target HRRP simulation in a simulation experiment. Detailed Embodiments

[0014] In order to make the purpose, technical solution and advantages of the present application clearer, the present application will be further described in detail below with reference to 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.

[0015] As Figure 1 shown, in the present application, a high-resolution range profile simulation method based on the segmented periodic modulation signal is provided, including the following steps: Step S100, obtain the target echo signal to be simulated, and extract the target feature information according to the one-dimensional high-resolution range profile of the target echo signal.

[0016] Step S110, determine the modulation parameters of the segmented periodic modulation signal according to the target feature information, and generate the segmented periodic modulation signal based on the determined modulation parameters.

[0017] Step S120, use the segmented periodic modulation signal to modulate the incident signal on the phase modulation surface to obtain the echo signal modulated by the phase modulation surface.

[0018] Step S130: Perform pulse compression processing on the echo signal after phase modulation on the phase modulation surface to obtain the simulated one-dimensional high-resolution range profile of the target echo signal.

[0019] In this application, a segmented periodic modulation signal based on a phase modulation metasurface is designed. The number of segments, modulation frequency, and duration are determined by the number, position, and intensity of the strong scattering points of the target HRRP respectively. After pulse compression, it can generate an HRRP similar to the characteristics of the real target.

[0020] First, introduce the segmented periodic modulation signal, the radar echo of the phase modulation surface and the one-dimensional high-resolution range profile, as well as the expression models of the radar echo and one-dimensional high-resolution range profile of the target.

[0021] Different from the traditional periodic intermittent modulation signal, the modulation period of the segmented periodic modulation signal changes in segments. According to different modulation frequencies, it can be divided into sub-sequences, and its time-domain waveform is as Figure 2 shown. Denote the segmented periodic modulation signal as , the th sub-sequence as , then the segmented periodic modulation signal is the sum of multiple sub-sequences, expressed as: (1) The radar echoes of the target and the phase modulation surface are respectively denoted as , , where the subscripts and respectively represent the data related to the target and the phase modulation surface. The corresponding HRRP can be obtained by the radar performing pulse compression processing on the echo, and are respectively denoted as , .

[0022] In this embodiment, the th sub-sequence is defined as: (2) In formula (2), the duration of the th sub-sequence is , the modulation period is , the duty cycle is , represents convolution, is the window function, is the impulse function, is the number of pulses contained in the th sub-sequence.

[0023] Next, perform Fourier transform on formula (2), and the expression of the sub-sequence in the frequency domain can be obtained as: (3) In formula (3), , is the Symle function, , .

[0024] In this embodiment, the radar echo signal of the phase modulation surface (PSS) Linear Frequency Modulation (LFM) signals are often used as transmitting signals for imaging radars. The radar echo signal after PSS modulation is: (4) In formula (4), is the scattering intensity of PSS, is the distance from PSS to radar, is the carrier frequency of LFM, is the frequency modulation slope of LFM, B is the bandwidth of LFM.

[0025] Furthermore, the one-dimensional high-resolution range image of the phase modulation surface The HRRP of PSS can be obtained by de-skewing the echo signal. First, the reference signal is assumed to be: (5) In formula (5), is the reference distance.

[0026] Next, the PSS echo signal With reference signal By multiplying the conjugate of and removing the remaining video phase, the difference frequency output is: (6) It can be seen from formula (6) that the second phase term is irrelevant to the calculation of HRRP. Perform Fourier transform on formula (6) and substitute the linear relationship between frequency and distance , then the one-dimensional high-resolution range image of the phase modulation surface can be obtained, which is expressed as: (7) In formula (7), is the distance variable, For the The modulation frequency of the subsequence. From formula (7), we can see that after PSS modulation, a series of discrete false peaks can be generated in the distance direction. The corresponding subsequence The positions and amplitudes of the false peaks are: (8) In this embodiment, the radar echo of the target is defined. Let the number of scattering points of the target be , the distance between the -th scattering point and the radar be , and the scattering intensity be . Then the target echo signal received by the radar is: (9) Furthermore, the one-dimensional high-resolution range profile (HRRP) of the target radar echo is defined. By multiplying the echo signal of the target by the conjugate of the reference signal and removing the residual video phase, the difference frequency output can be obtained as: (10) From formula (10), it can be seen that the second phase term has nothing to do with the calculation of HRRP. Perform Fourier transform on formula (10) and substitute the linear relationship between frequency and distance . The one-dimensional high-resolution range profile of the target radar echo can be obtained, expressed as: (11) It can be obtained from formula (11) that the position and amplitude of the -th scattering point of the target on the HRRP are respectively: (12) In step S100, first extract the number of discrete peaks, the position of each discrete peak, and the amplitude in the one-dimensional high-resolution range profile of the radar echo signal of the target to be simulated, and use the number of discrete peaks, the positions and amplitudes of the discrete peaks as target feature information. Actually, the target feature information of the target to be simulated can be stored in advance and directly called during HRRP simulation.

[0027] In step S110, the modulation parameters of the segmented periodic modulation signal include: the number of segments of the segmented periodic modulation signal, the modulation frequency, the duty cycle, and the duration.

[0028] In this embodiment, determining the modulation parameters of the segmented periodic modulation signal according to the target feature information includes: determining the number of segments according to the number of discrete peaks in the one-dimensional high-resolution range profile. Determine the modulation frequency by aligning the positions of the false targets in each subsequence of the segmented periodic modulation signal with the positions of the corresponding target scattering points in the one-dimensional high-resolution range profile. Determine the duration by aligning the normalized amplitudes of the false targets in each subsequence of the segmented periodic modulation signal with the normalized amplitudes of the corresponding target scattering points in the one-dimensional high-resolution range profile.

[0029] In this embodiment, to achieve the blanking of PSS at the original position, the fixed modulation duty cycle is 0.5. Considering that, except for the 0th order peak, the energy of the ±1st order false targets of the interferer is the largest, so the simulation of the target HRRP is realized based on the -1st order false target, that is .

[0030] Specifically, set the number of segments of the modulation signal to be equal to the number of discrete peaks of the target HRRP, that is: (13) In formula (13), and are the number of segments of the modulation signal and the number of discrete peaks of the target HRRP respectively.

[0031] Specifically, set the modulation frequency of each sub-sequence so that the -1st order false target of the th sub-sequence is aligned with the position of the rd scattering point of the target, that is: (14) Substitute formula (14) into formulas (8) and (12) to obtain the formula for calculating the modulation frequency, expressed as: (15) In formula (15), represents the modulation frequency of the th sub-sequence, represents the frequency modulation slope of the linear frequency modulation signal, represents the speed of light, represents the distance between the th peak of the target and the radar, is the distance between the phase modulation surface and the radar.

[0032] Specifically, set the duration of each sub-sequence so that the -1st order false target of the th sub-sequence has the same normalized amplitude as the HRRP corresponding to the th scattering point of the target, that is: (16) Similarly, substitute formula (16) into formulas (8) and (12) to obtain the formula for calculating the duration, expressed as: (17) In formula (17), represents the duration of the th sub-sequence, represents the scattering intensity of the th peak of the target, represents the pulse width of the linear frequency modulation signal.

[0033] Further, after determining the number of segments, modulation frequency, duty cycle, and duration of the segmented periodic modulation signal, the segmented periodic modulation signal can be generated.

[0034] In step S120, the incident signal on the phase modulation surface is modulated by the segmented periodic modulation signal to obtain the phase-modulated signal.

[0035] In step S130, after performing pulse compression processing on the echo signal modulated by the phase modulation surface, the simulated HRRP of the target can be obtained.

[0036] In this paper, the effectiveness of the proposed method is also verified through simulation experiments. Experimental scenario and radar parameter settings: A target with three strong scattering points is set for simulation experiments. The distances of the three scattering points are 5m, 10m, and 13m respectively, and the scattering intensities are all 1. The phase modulation surface is located at 0m with a scattering intensity of 2. The carrier frequency of the LFM signal transmitted by the radar is 10GHz, the pulse width is 100us, and the bandwidth is 1GHz.

[0037] Signal parameter settings: The modulation signal is divided into three sub-sequences. The duration of the first sub-sequence is 20us, and the modulation frequency is 555.56KHz; the duration of the second sub-sequence is 20us, and the modulation frequency is 1.11MHz; the duration of the third sub-sequence is 20us, and the modulation frequency is 1.444MHz.

[0038] The results of the simulation experiment are shown in Figure 3 。 Figure 3 . The solid line and the dashed line in the figure are the HRRP of the target and the HRRP of the phase modulation surface respectively. It can be seen from the figure that after modulation, the phase modulation surface generates three -1 order false peaks, and their positions and amplitudes are in good agreement with the three discrete peaks in the target HRRP, which verifies the effectiveness of the proposed method.

[0039] In the above high-resolution range profile simulation method based on segmented periodic modulation signals, by extracting the target feature information of the one-dimensional high-resolution range profile of the target to be simulated, the modulation parameters of the segmented periodic modulation signal are determined according to the target feature information. Based on the determined modulation parameters, the segmented periodic modulation signal is generated. The segmented periodic modulation signal is used to modulate the incident signal on the phase modulation surface to obtain the phase modulation signal, and the pulse compression processing is performed on the phase modulation signal to obtain the simulated one-dimensional high-resolution range profile of the target echo signal. Compared with the traditional periodic modulation signal, the designed segmented periodic modulation signal of this method can generate a series of irregularly distributed false images, and the modulation pattern is more flexible and variable. By extracting the number and amplitude of the target HRRP peaks, this method can realize the realistic simulation of the target HRRP based on a single phase modulation surface, with the advantages of high cost-effectiveness and simple parameter calculation.

[0040] It should be understood that although Figure 1 the steps in the flowchart of Figure 1 are shown in sequence according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear description in this article, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover,

[0041] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as within the scope described in this specification.

[0042] The above-described embodiments only represent one implementation manner of the present application, and its description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A high-resolution range profile simulation method based on segmented periodic modulation signal, characterized in that: The method comprises: Acquire a target echo signal to be simulated, and extract target feature information according to a one-dimensional high-resolution range image of the target echo signal; Determine the modulation parameters of the segmented periodic modulation signal according to the target characteristic information, and generate the segmented periodic modulation signal based on the determined modulation parameters; Using the segmented periodic modulation signal to modulate the incident signal of the phase modulation surface, to obtain an echo signal modulated by the phase modulation surface; The echo signal modulated by the phase modulation surface is subjected to pulse compression processing to obtain a simulated one-dimensional high-resolution range image of the target echo signal.

2. The high-resolution range profile simulation method based on segmented periodic modulation signal according to claim 1, characterized in that: The number of discrete peaks, the position of each discrete peak, and the amplitude are extracted from the one-dimensional high-resolution range image of the target echo signal, and the number of discrete peaks, the position and amplitude of each discrete peak are used as the target feature information.

3. The high-resolution range profile simulation method based on segmented periodic modulation signal according to claim 2, characterized in that: The modulation parameters include: the number of segments, modulation frequency, duty cycle and duration of the segmented periodic modulation signal.

4. The high-resolution range profile simulation method based on segmented periodic modulation signal according to claim 3 is characterized in that: Determining the modulation parameters of the segmented periodic modulation signal according to the target characteristic information includes: Determining the number of segments according to the number of discrete peaks in the one-dimensional high-resolution range image; Determining the modulation frequency by aligning the position of the -1 order false target in each subsequence in the segmented periodic modulation signal with the position of the corresponding target scattering point in the one-dimensional high-resolution range image; The duration is determined by aligning the normalized amplitude of the -1 order false target in each subsequence in the segmented periodic modulation signal with the normalized amplitude of the corresponding target scattering point in the one-dimensional high-resolution range image.

5. The high-resolution range profile simulation method based on segmented periodic modulation signal according to claim 4, characterized in that: The duty cycle is set to 0.

5.

6. The high-resolution range profile simulation method based on segmented periodic modulation signal according to claim 4, characterized in that: To determine the modulation frequency, the following formula is used: In the above formula, Indicates The modulation frequency of the segment sequence, represents the frequency modulation slope of the linear frequency modulation signal, represents the speed of light, Indicates the target The distance between the peak and the radar, is the distance between the phase modulation surface and the radar.

7. The high-resolution range profile simulation method based on segmented periodic modulation signal according to claim 4, characterized in that: To determine the duration, use the following formula: In the above formula, Indicates The duration of the segment sequence, Indicates the target The peak scattering intensity is Indicates the pulse width of the linear frequency modulation signal.

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