SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on time modulation metasurface

Abstract

The invention discloses an SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on a time modulation metasurface, and relates to the technical field of microwave remote sensing. An intra-pulse multi-phase segmented modulation signal and an inter-pulse multi-phase segmented modulation signal can be respectively obtained, the two kinds of modulation signals are multiplied to obtain a two-dimensional multi-phase segmented modulation signal, and a multi-region two-dimensional multi-phase segmented interference signal is formed; by means of two-dimensional intra-pulse and inter-pulse multi-phase segmented modulation, fine control over radar signals can be achieved, reflected signals can present discontinuous and aperiodic characteristics in time, the utilization rate of electromagnetic waves incident to the metasurface is increased through the operation, the modulation efficiency during modulation is improved, the radar signal processing difficulty is increased, and the radar signal processing efficiency is improved. The SAR-GMTI system is difficult to extract useful target information from the reflected signal, and the interference effect on the SAR-GMTI system is finally improved.

Description

Technical Field

[0001] The present invention relates to the field of microwave remote sensing technology, and in particular to a SAR-GMTI two-dimensional multi-phase segmented modulation interference method, device, equipment and medium based on a time-modulated metasurface. Background Art

[0002] Synthetic aperture radar (SAR) is a high-resolution imaging radar with the advantages of all-day, all-weather and long-range. Combining the SAR system with the ground moving target indication (GMTI) technology, namely SAR-GMTI technology, can achieve the integration of imaging and moving target detection, which is an important development trend of military reconnaissance and battlefield perception technology. This poses a serious threat to the military deployment, combat status, wartime survival, etc. of important ground targets such as armored vehicles, tanks, missile launchers and other mobile strategic targets. Therefore, it is imperative to study effective interference countermeasures based on the characteristics of SAR-GMTI in the field of electronic countermeasures.

[0003] SAR-GMTI combines the two working modes of SAR and GMTI, and has a certain suppression ability for background clutter. In order to implement effective interference, it is necessary not only to interfere with the SAR imaging system, but also to prevent the false interference target from being eliminated after GMTI processing; traditional SAR-GMTI interference methods can be divided into active deception interference and passive interference; in active deception interference, the electromagnetic interference environment faced by modern radars is becoming more and more complex. Not only are the interference styles more complex and changeable, but the interference methods are usually a combination of multiple clutter interference, passive interference, suppression interference, deception interference, etc., and most of the current interference identification methods only consider a single type of interference, resulting in limited recognition ability of radar when subjected to complex interference, making the interference environment perception ability of active deception interference limited; in passive interference, due to the decline in channel quality, the data transmission rate of the wireless communication system may have to be reduced to adapt to worse channel conditions. This phenomenon increases the delay in data transmission and affects the real-time performance of the system.

[0004] With the advancement of technology, the emergence of new metasurfaces such as time-modulated surfaces, perfect metasurface absorbers, and coded metasurfaces has provided a new design idea for SAR-GMTI jamming technology. By applying metasurface technology, important parameters such as radar echo signal delay, polarization, phase, frequency, and amplitude can be precisely controlled without actively transmitting signals, thereby achieving SAR-GMTI jamming effects. At present, the modulation of electromagnetic metasurfaces is mainly phase control. The principle is to precisely control the amplitude and phase of electromagnetic waves by controlling the unit structure and phase delay of the metasurface. By changing the material, size, shape and other parameters of the metasurface, the metasurface can be controlled to adjust the phase of the light wave. It is usually used in optics to make quarter-wave plates, half-wave plates, polarizers, superlenses, quasi-holograms, optical vortex generators, etc. It can also be used in communications and radar systems, with the capabilities of antenna design, imaging and focusing; but in phase control methods, such as the diffraction space division method, the incident electromagnetic wave will be divided into different parts to produce different phase responses, which usually means that only part of the electromagnetic wave is effectively utilized to produce the required phase change, while the rest may exist as background noise or divergent field, resulting in reduced electromagnetic wave utilization, making the modulation efficiency low when modulating the incident electromagnetic wave, reducing the interference effect on the SAR-GMTI system. Summary of the invention

[0005] The embodiment of the present invention provides a SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on a time-modulated metasurface, which can solve the problem in the prior art that the current method leads to a reduction in the utilization rate of electromagnetic waves, resulting in low modulation efficiency when modulating the incident electromagnetic waves, thereby reducing the interference effect on the SAR-GMTI system.

[0006] The embodiment of the present invention provides a SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on a time modulation metasurface, comprising:

[0007] Design a time-modulated metasurface and install it on the target surface;

[0008] When the protected target is moving, the time modulation metasurface designed on the surface receives the radar transmission signals of the SAR-GMTI system in the form of multiple regions, and the time modulation metasurface performs two-dimensional intra-pulse multi-phase segmented modulation and slow-time two-dimensional inter-pulse multi-phase segmented modulation on the transmission signals of the multiple regions, respectively, and obtains the intra-pulse multi-phase segmented modulation signal and the inter-pulse multi-phase segmented modulation signal, respectively, and multiplies the intra-pulse multi-phase segmented modulation signal and the inter-pulse multi-phase segmented modulation signal to obtain the two-dimensional multi-phase segmented modulation signal, and form the two-dimensional multi-phase segmented modulation signal of multiple regions;

[0009] A two-dimensional multi-phase segmented interference signal with multiple regions is generated according to the frequency spectrum of the two-dimensional multi-phase segmented modulation signal, and the SAR-GMTI system is interfered with by the two-dimensional multi-phase segmented interference signal with multiple regions.

[0010] Preferably, the forming of the two-dimensional multi-phase segmented modulation signal comprises:

[0011] When the radar transmission signal of the SAR-GMTI system is incident on the time-modulated metasurface, the phase of the electromagnetic wave signal incident on the time-modulated metasurface is subjected to two-dimensional intra-pulse multi-phase segmented modulation and slow-time two-dimensional inter-pulse multi-phase segmented modulation, respectively, to obtain intra-pulse multi-phase segmented modulation signals and inter-pulse multi-phase segmented modulation signals;

[0012] The intra-pulse multi-phase segmented modulation signal and the inter-pulse multi-phase segmented modulation signal are respectively:

[0013]

[0014] in: represents the multi-phase segmented modulation signal within the pulse; p2(t m ) represents the pulse-to-pulse multi-phase segmented modulation signal; * represents the convolution operation; τ1,T1,f1=1 / T1,φ p1 , P1, N1 represent the segment duration, modulation period, modulation frequency, modulation phase, number of phase segments within the pulse, and number of repetitions of the intra-pulse multi-phase segment modulation signal respectively; τ2, T2, f2 = 1 / T2, φ p2 , P2, N2 represent the segment duration, modulation period, modulation frequency, modulation phase, number of segmentation between pulses, and number of repetitions of the inter-pulse multi-phase segmented modulation signal respectively;

[0015] The two-dimensional multi-phase segmented modulation signal is:

[0016]

[0017] Where: t m Indicates slow time; Represents a two-dimensional multi-phase segmented modulation signal.

[0018] Preferably, the extraction of the spectrum of the two-dimensional multi-phase segmented modulation signal includes:

[0019] According to the modulation frequency f1 of the intra-pulse multi-phase segmented modulation signal and the modulation frequency f2 of the inter-pulse multi-phase segmented modulation signal, the frequency domain of the intra-pulse multi-phase segmented modulation signal and the frequency domain of the inter-pulse multi-phase segmented modulation signal are obtained respectively as follows:

[0020]

[0021]

[0022] in: represents the frequency domain of the multi-phase segmented modulation signal within the pulse; p2(t m ) represents the frequency domain of the pulse-to-pulse multi-phase segmented modulation signal;

[0023] The spectrum of the two-dimensional multi-phase segmented modulation signal is formed by weighting the amplitude of the intra-pulse multi-phase segmented modulation signal and the amplitude of the inter-pulse multi-phase segmented modulation signal.

[0024] Preferably, the formation of the multi-region two-dimensional multi-phase segmented interference signal includes:

[0025] The spectrum of the two-dimensional multi-phase segmented modulation signal in the frequency domain is extracted, and the spectrum of the two-dimensional multi-phase segmented modulation signal is subjected to multiple periodic weighted expansions in the range and azimuth directions of the protected target, and the spectrum of the two-dimensional multi-phase segmented modulation signal is replaced with multiple different spectrums generated in the range and azimuth directions in sequence, and multiple harmonic components of the two-dimensional multi-phase segmented modulation signal are formed in the range and azimuth directions respectively, and the multiple harmonic components in the range and azimuth directions are synthesized into a two-dimensional multi-phase segmented interference signal, and a two-dimensional multi-phase segmented interference signal in multiple regions is formed.

[0026] Preferably, the two-dimensional multi-phase segmented interference signal is:

[0027]

[0028] Wherein: f1 represents the modulation frequency of the intra-pulse multi-phase segmented modulation signal; f2 represents the modulation frequency of the inter-pulse multi-phase segmented modulation signal.

[0029] Preferably, interfering with the SAR-GMTI system includes:

[0030] The SAR-GMTI system receives two-dimensional multi-phase segmented interference signals from multiple regions, and performs range matching filtering, range migration correction and clutter suppression on the interference signals, forming a multi-region array of false targets with different intervals in the range and azimuth directions of the protected target in the interference image, thereby achieving interference with the SAR-GMTI system.

[0031] The offsets of the mnth false target in the distance dimension and the azimuth dimension are:

[0032]

[0033] Wherein: f1 represents the modulation frequency of the multi-phase segmented modulation signal within a pulse; f2 represents the modulation frequency of the multi-phase segmented modulation signal between pulses; γ represents the Doppler modulation frequency in the distance direction; μ represents the Doppler modulation frequency in the azimuth direction; λ represents the wavelength; and c represents the speed of light.

[0034] The embodiment of the present invention also provides a SAR-GMTI two-dimensional multi-phase segmented modulation interference device based on a time modulation metasurface, comprising:

[0035] A design module, used to design a time-modulated metasurface and install it on the surface of the protection target;

[0036] Modulation module, when the protected target is moving, the time modulation metasurface designed on the surface receives the radar transmission signal of the SAR-GMTI system in the form of multiple regions, and the time modulation metasurface performs two-dimensional intra-pulse multi-phase segmented modulation and slow-time two-dimensional inter-pulse multi-phase segmented modulation on the transmission signals of the multiple regions, respectively, obtains the intra-pulse multi-phase segmented modulation signal and the inter-pulse multi-phase segmented modulation signal, multiplies the intra-pulse multi-phase segmented modulation signal and the inter-pulse multi-phase segmented modulation signal to obtain the two-dimensional multi-phase segmented modulation signal, and forms the two-dimensional multi-phase segmented modulation signal of multiple regions;

[0037] The SAR-GMTI system interference module generates a multi-region two-dimensional multi-phase segmented interference signal according to the frequency spectrum of the two-dimensional multi-phase segmented modulation signal, and interferes with the SAR-GMTI system through the multi-region two-dimensional multi-phase segmented interference signal.

[0038] An embodiment of the present invention further provides an electronic device, including a memory and a processor;

[0039] The memory is used to store computer programs;

[0040] The processor is used to implement the steps of the SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on time-modulated metasurface as described above when executing the computer program stored in the memory.

[0041] An embodiment of the present invention also provides a computer-readable storage medium for storing a computer program, which, when executed by a processor, implements the steps of the SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on time-modulated metasurface as described above.

[0042] The embodiment of the present invention provides a SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on a time-modulated metasurface. Compared with the prior art, the method has the following beneficial effects:

[0043] The present invention can obtain intra-pulse multi-phase segmented modulation signals and inter-pulse multi-phase segmented modulation signals respectively through two-dimensional intra-pulse multi-phase segmented modulation and slow-time two-dimensional inter-pulse multi-phase segmented modulation. The two modulation signals are multiplied to obtain a two-dimensional multi-phase segmented modulation signal, and form a two-dimensional multi-phase segmented interference signal in multiple regions; two-dimensional intra-pulse and inter-pulse multi-phase segmented modulation can realize refined control of radar signals, and can make the reflected signals present non-continuous and non-periodic characteristics in time. This operation improves the utilization rate of electromagnetic waves incident on the metasurface to improve the modulation efficiency during modulation, which increases the difficulty of radar signal processing. It is difficult for the SAR-GMTI system to extract useful target information from the reflected signals, and ultimately improves the effect of interference to the SAR-GMTI system.

[0044] Moreover, through complex modulation such as two-dimensional intra-pulse multi-phase segmented modulation and slow-time two-dimensional inter-pulse multi-phase segmented modulation, the reflected signal becomes difficult to predict and analyze in both time domain and frequency domain, which significantly reduces the SAR-GMTI system's detection and identification capabilities for the protected target, thereby enhancing the target's stealth performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of the overall process of a SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on a time-modulated metasurface provided in an embodiment of the present invention;

[0046] Figure 2 A schematic diagram of an interference model of a SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on a time-modulated metasurface provided in an embodiment of the present invention;

[0047] Figure 3 A schematic diagram of the design of a time-modulated metasurface for a SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on a time-modulated metasurface provided in an embodiment of the present invention; (a) is a schematic diagram of the structure of the metasurface; (b) is a schematic diagram of a metasurface array;

[0048] Figure 4 A schematic diagram of single-channel SAR imaging results without interference using the SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on the time-modulated metasurface provided in an embodiment of the present invention;

[0049] Figure 5 A schematic diagram of single-channel SAR interference imaging results of the SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on the time-modulated metasurface provided in an embodiment of the present invention;

[0050] Figure 6A schematic diagram of multi-channel clutter suppression results in the absence of interference using a SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on a time-modulated metasurface provided in an embodiment of the present invention;

[0051] Figure 7 A schematic diagram of multi-channel clutter suppression results of a SAR-GMTI two-dimensional multi-phase segmented modulation jamming method based on a time-modulated metasurface provided in an embodiment of the present invention;

[0052] Figure 8 A schematic diagram of the moving target detection results in the absence of interference using the SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on the time-modulated metasurface provided in an embodiment of the present invention;

[0053] Fig. 9 A schematic diagram of the moving target detection results of the SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on the time-modulated metasurface provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0055] See also Figure 1 The embodiment of the present invention provides a SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on a time-modulated metasurface, comprising the following steps:

[0056] Step 1: Construction of a multi-channel SAR-GMTI interference signal model based on time-modulated metasurface.

[0057] Step 2: Design of time-modulated metasurface.

[0058] Step 3: Establishment and generation of a two-dimensional multi-phase segmented modulation signal model based on the time-modulated metasurface.

[0059] Step 4: Multi-channel SAR-GMTI processing and interference effect analysis.

[0060] The construction of the multi-channel SAR-GMTI interference signal model in step 1 is as follows:

[0061] The dual-channel SAR-GMTI interference model based on time-modulated metasurface is as follows: Figure 2As shown in the figure; it is assumed that the SAR-GMTI system works in the positive side-view mode, the radar platform is at a height of H from the ground, and flies along the X-axis at a constant speed V; a phased array antenna is placed horizontally along the tangent direction of the radar track, and the antenna is divided into two sub-antennas, d is the distance between the two sub-antennas; a single-transmit dual-receive working mode is adopted, antenna 1 transmits the LFM signal, and the two sub-antennas receive the echo signal simultaneously; according to the antenna phase center equivalent principle, the antenna one-transmit multiple-receive data acquisition mode can be equivalent to the multi-antenna self-transmitting and self-receiving mode; at the azimuth slow time t m At time , the position vector of the i-th equivalent antenna is expressed as and are the unit vectors of the X-axis and Z-axis respectively; the phase modulated metasurface is placed on the surface of the protected moving target in the observation scene, and the target moves at a speed v(t m ) moves in the scene, and the position vector is expressed as in, represents the unit vector of the Y axis, x0 and y0 are the initial positions of the moving target, and v x and v r =v y sinφ represents the tangential velocity and radial velocity of the moving target, v y is the ground range velocity of the moving target, and φ represents the radar downward viewing angle.

[0062] The instantaneous slant range R between the i-th equivalent antenna and the moving target i (t m ) is expressed as:

[0063]

[0064] Assume that the LFM signal transmitted by the SAR-GMTI system is expressed as:

[0065]

[0066] in: Indicates distance to fast time; T r represents the pulse width; rect(·) represents the rectangular function; f0 represents the center frequency of the transmitted signal; μ represents the modulation frequency of the transmitted LFM signal.

[0067] The time-modulated metasurface on the target surface intercepts the radar transmission signal and performs interference modulation on it. Under the control of the external bias voltage, the time metasurface modulates the phase information of the transmission signal in real time and forwards the modulated signal to the SAR-GMTI system. The SAR-GMTI system performs detection and demodulation on the received interference echo signal. The complex baseband interference signal corresponding to the equivalent antenna i can be expressed as:

[0068]

[0069] in: represents a modulation signal generated by a time-modulated metasurface; represents the unmodulated moving target echo signal received by antenna i, and the expression is:

[0070]

[0071] Where: A represents the complex reflection coefficient of the target; T a represents the synthetic aperture time; λ and c represent the wavelength and the speed of light, respectively.

[0072] In addition to the above interference signals, the total echo signal received by the radar is Also includes the echo signal generated by background clutter and system noise Echo signal The expression is:

[0073]

[0074] Since the phase information in the moving target echo signal is destroyed by the modulated signal, false targets or defocused images appear in the SAR image after clutter suppression and imaging processing, which effectively interferes with the detection and imaging of moving targets.

[0075] The design of the time-modulated metasurface in step 2 is as follows:

[0076] First, a double-layer butterfly metal structure is designed, and a lumped element, a varactor diode, is added between the butterfly metal gap structures. The voltage on both sides of the varactor diode is adjusted to change the equivalent capacitance, so that the phase of the incident electromagnetic wave can be continuously changed. The designed electromagnetic metasurface unit structure and array structure schematic diagram are shown in the figure. Figure 3 As shown, the array structure layout is achieved by performing a two-dimensional periodic translation of the unit structure, thereby realizing a complete two-dimensional electromagnetic metasurface array structure.

[0077] The establishment and generation of the two-dimensional multi-phase segmented modulation signal model in step three is specifically as follows:

[0078] The two-dimensional multi-part segmented modulation signal based on the time-modulated metasurface can be expressed as:

[0079]

[0080] Where: Intra-pulse multi-phase segmented modulation signal and the pulse-to-pulse multi-phase segmented modulation signal p2(t m ) are respectively expressed as:

[0081]

[0082] Where: * represents convolution operation; τ1,T1,f1=1 / T1,φ p1 , P1, N1 represent the segment duration, modulation period, modulation frequency, modulation phase, number of intra-pulse phase segments, and number of repetitions of the intra-pulse modulation signal respectively; τ2, T2, f2 = 1 / T2, φ p2 , P2, N2 represent the segment duration, modulation period, modulation frequency, modulation phase, number of inter-pulse phase segments, and number of repetitions of the inter-pulse modulation signal respectively.

[0083] and p2(t m ) are expressed in the frequency domain as follows:

[0084]

[0085] Therefore, the interference signal can be expressed in the two-dimensional frequency domain as:

[0086]

[0087] in:

[0088] It can be seen from the above formula that after two-dimensional multi-phase segmented modulation processing, the spectrum of the interference signal is the periodic weighted expansion of the original echo spectrum along the range and azimuth directions. The periods in the range and azimuth directions are the modulation frequencies f1 and f2 respectively, and its amplitude is jointly modulated by multiple phases.

[0089] The multi-channel SAR-GMTI processing and interference effect analysis in step 4 are as follows:

[0090] First, the radar echo signal is processed by range-Doppler SAR imaging. After range-matched filtering and range migration correction, the interference signal and background clutter echo signal can be expressed as:

[0091]

[0092] Among them: B r Indicates the bandwidth of the transmitted signal; Indicates rounding up.

[0093] Converting the radar echo signal to the Doppler frequency domain, the relationship between the stationary clutter echo signals received by the two antennas can be expressed as:

[0094]

[0095] Where: γ c =-2V 2 / (λR B );Δt=d / V;B a Represents the signal Doppler bandwidth.

[0096] The relationship between the interference signals received by the two antennas is expressed as:

[0097]

[0098] According to the relationship between the echo signals received by the two antennas, the present invention uses a dual-channel offset phase center antenna (DPCA) method to achieve clutter suppression; its expression is:

[0099]

[0100] in: It represents the residual clutter and noise caused by non-ideal factors such as non-ideal characteristics of the device, internal noise of the system, temperature and external environment.

[0101] The echo signal after clutter suppression is processed by azimuth matched filtering to obtain the final interference SAR-GMTI image, which is expressed as:

[0102]

[0103] in:

[0104] It can be seen that after range-Doppler imaging and DPCA clutter suppression processing, (2N+1)×(2M+1) false targets are generated in the interfering SAR-GMTI image, and the offset of the mnth false target in the range dimension and azimuth dimension can be expressed as:

[0105]

[0106] The specific tests are:

[0107] A reference moving target RT and two protected moving targets PT1-2 are set at the center of the imaging scene, and uniform background clutter and noise with a signal-to-noise ratio of SCNR=0dB are added; the echo signal of the protected target is modulated in two-dimensional multi-phase segmentation using the time-modulated metasurface, and the intra-pulse and inter-pulse modulation frequencies are set to f1=6250KHz and f2=9.37Hz, respectively, and the intra-pulse and inter-pulse segment phases are set to φ p1 =0, 0.3π, 0.6π, π and φ q2 =0, 0.5π, 0.8π, π; perform range-Doppler SAR imaging processing on the unmodulated echo signal and the interference signal, and obtain the unmodulated single-channel SAR imaging result and the single-channel interference imaging result, respectively, as shown in Figure 4 and Figure 5 As shown, it can be seen that the moving target is submerged in the clutter, making it difficult to directly detect the moving target.

[0108] After dual-channel DPCA processing, the non-interference clutter suppression results and the modulation interference clutter suppression results are obtained as follows: Figure 6 and Figure 7 As shown in Figure 1, it can be seen that after the two-dimensional multi-phase segmented modulation processing based on the time-modulated metasurface, the protected target generates a two-dimensional false target array with a topological structure similar to the protected target, and the distance and azimuth offset of each false target are proportional to the modulation frequency. On this basis, CFAR detection is performed on the clutter-suppressed SAR-GMTI image to obtain the final moving target detection result. The non-interference detection result and the modulation interference detection result are shown in Figure 1, respectively. Figure 8 and Fig. 9 As shown; the interference image obtained by two-dimensional multi-phase segmented modulation processing contains a large number of false targets, which effectively interferes with the detection of moving targets and subsequent target recognition. Therefore, the method designed by the present invention has a high flexibility, high fidelity, and low-cost SAR-GMTI interference effect.

[0109] The present invention utilizes a time-modulated metasurface to generate a two-dimensional multi-phase segmented modulation signal, realizes phase modulation of a radar signal to generate a multi-channel SAR-GMTI interference signal; by processing the SAR-GMTI interference signal, theoretical analysis and experimental results show that the present invention can generate a two-dimensional false target array with flexible and controllable distance and azimuth position and a topological structure similar to that of the protected target, thereby obtaining a SAR-GMTI interference effect with high flexibility, high fidelity and low cost.

[0110] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on a time-modulated metasurface, characterized in that: The following steps are involved: Design a time-modulated metasurface and install it on the target surface; When the protected target is moving, the time modulation metasurface designed on the surface receives the radar transmission signals of the SAR-GMTI system in the form of multiple regions, and the time modulation metasurface performs two-dimensional intra-pulse multi-phase segmented modulation and slow-time two-dimensional inter-pulse multi-phase segmented modulation on the transmission signals of the multiple regions, respectively, and obtains the intra-pulse multi-phase segmented modulation signal and the inter-pulse multi-phase segmented modulation signal, respectively, and multiplies the intra-pulse multi-phase segmented modulation signal and the inter-pulse multi-phase segmented modulation signal to obtain the two-dimensional multi-phase segmented modulation signal, and form the two-dimensional multi-phase segmented modulation signal of multiple regions; A two-dimensional multi-phase segmented interference signal with multiple regions is generated according to the frequency spectrum of the two-dimensional multi-phase segmented modulation signal, and the SAR-GMTI system is interfered with by the two-dimensional multi-phase segmented interference signal with multiple regions.

2. The SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on time-modulated metasurface according to claim 1 is characterized in that: The formation of the two-dimensional multi-phase segmented modulation signal includes: When the radar transmission signal of the SAR-GMTI system is incident on the time-modulated metasurface, the phase of the electromagnetic wave signal incident on the time-modulated metasurface is subjected to two-dimensional intra-pulse multi-phase segmented modulation and slow-time two-dimensional inter-pulse multi-phase segmented modulation, respectively, to obtain intra-pulse multi-phase segmented modulation signals and inter-pulse multi-phase segmented modulation signals; The intra-pulse multi-phase segmented modulation signal and the inter-pulse multi-phase segmented modulation signal are respectively: in: represents the multi-phase segmented modulation signal within the pulse; p2(t m ) represents the pulse-to-pulse multi-phase segmented modulation signal; * represents the convolution operation; τ1,T1,f1=1 / T1,φ p1 , P1, N1 represent the segment duration, modulation period, modulation frequency, modulation phase, number of phase segments within the pulse, and number of repetitions of the intra-pulse multi-phase segment modulation signal respectively; τ2, T2, f2 = 1 / T2, φ p2 , P2, N2 represent the segment duration, modulation period, modulation frequency, modulation phase, number of segmentation between pulses, and number of repetitions of the inter-pulse multi-phase segmented modulation signal respectively; The two-dimensional multi-phase segmented modulation signal is: Where: t m Indicates slow time; Represents a two-dimensional multi-phase segmented modulation signal.

3. The SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on time-modulated metasurface according to claim 2 is characterized in that: The extraction of the spectrum of the two-dimensional multi-phase segmented modulation signal comprises: According to the modulation frequency f1 of the intra-pulse multi-phase segmented modulation signal and the modulation frequency f2 of the inter-pulse multi-phase segmented modulation signal, the frequency domain of the intra-pulse multi-phase segmented modulation signal and the frequency domain of the inter-pulse multi-phase segmented modulation signal are obtained respectively as follows: in: represents the frequency domain of the multi-phase segmented modulation signal within the pulse; p2(t m ) represents the frequency domain of the pulse-to-pulse multi-phase segmented modulation signal; The spectrum of the two-dimensional multi-phase segmented modulation signal is formed by weighting the amplitude of the intra-pulse multi-phase segmented modulation signal and the amplitude of the inter-pulse multi-phase segmented modulation signal.

4. The SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on time-modulated metasurface according to claim 3 is characterized in that: The formation of the multi-region two-dimensional multi-phase segmented interference signal includes: The spectrum of the two-dimensional multi-phase segmented modulation signal in the frequency domain is extracted, and the spectrum of the two-dimensional multi-phase segmented modulation signal is subjected to multiple periodic weighted expansions in the range and azimuth directions of the protected target, and the spectrum of the two-dimensional multi-phase segmented modulation signal is replaced with multiple different spectrums generated in the range and azimuth directions in sequence, respectively, to form multiple harmonic components of the two-dimensional multi-phase segmented modulation signal in the range and azimuth directions, and the multiple harmonic components in the range and azimuth directions are synthesized into a two-dimensional multi-phase segmented interference signal, thereby forming a two-dimensional multi-phase segmented interference signal in multiple regions.

5. The SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on time-modulated metasurface according to claim 4 is characterized in that: The two-dimensional multi-phase segmented interference signal is: Wherein: f1 represents the modulation frequency of the intra-pulse multi-phase segmented modulation signal; f2 represents the modulation frequency of the inter-pulse multi-phase segmented modulation signal.

6. The SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on time-modulated metasurface according to claim 5 is characterized in that: The interference to the SAR-GMTI system includes: The SAR-GMTI system receives two-dimensional multi-phase segmented interference signals from multiple regions, and performs range matching filtering, range migration correction and clutter suppression on the interference signals, forming a multi-region array of false targets with different intervals in the range and azimuth directions of the protected target in the interference image, thereby achieving interference with the SAR-GMTI system. The offsets of the mnth false target in the distance dimension and the azimuth dimension are: Wherein: f1 represents the modulation frequency of the multi-phase segmented modulation signal within a pulse; f2 represents the modulation frequency of the multi-phase segmented modulation signal between pulses; γ represents the Doppler modulation frequency in the distance direction; μ represents the Doppler modulation frequency in the azimuth direction; λ represents the wavelength; and c represents the speed of light.

7. SAR-GMTI two-dimensional multi-phase segmented modulation jammer based on time-modulated metasurface, characterized in that: include: A design module, used to design a time-modulated metasurface and install it on the surface of the protection target; Modulation module, when the protected target is moving, the time modulation metasurface designed on the surface receives the radar transmission signal of the SAR-GMTI system in the form of multiple regions, and the time modulation metasurface performs two-dimensional intra-pulse multi-phase segmented modulation and slow-time two-dimensional inter-pulse multi-phase segmented modulation on the transmission signals of the multiple regions, respectively, obtains the intra-pulse multi-phase segmented modulation signal and the inter-pulse multi-phase segmented modulation signal, multiplies the intra-pulse multi-phase segmented modulation signal and the inter-pulse multi-phase segmented modulation signal to obtain the two-dimensional multi-phase segmented modulation signal, and forms the two-dimensional multi-phase segmented modulation signal of multiple regions; The SAR-GMTI system interference module generates a multi-region two-dimensional multi-phase segmented interference signal according to the frequency spectrum of the two-dimensional multi-phase segmented modulation signal, and interferes with the SAR-GMTI system through the multi-region two-dimensional multi-phase segmented interference signal.

8. An electronic device, characterized in that: including memory and processor; The memory is used to store computer programs; The processor is used to execute the computer program stored in the memory to implement the steps of the SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on time-modulated metasurface as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that: Used to store a computer program, which, when executed by a processor, implements the steps of the SAR-GMTI two-dimensional multi-phase segmented modulation interference method based on a time-modulated metasurface as described in any one of claims 1 to 6.

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