Simulation method for focusing efficiency of time reversal under motion time reversal mirror

Abstract

The application relates to a simulation method for the focusing effect of a moving time reversal mirror, belonging to the field of electromagnetic energy focusing, and solving the problem that the existing method cannot simulate the focusing effect of a moving time reversal system. The method comprises the following steps: a target F transmits a signal; receiving channel information of a time reversal mirror unit at a first position and the target, and transmission channel information of the time reversal mirror unit at a second position and the neighborhood of the target are obtained; the time reversal mirror unit moves at a speed v and reaches the second position after a time T; based on the receiving channel information, a signal received by the time reversal mirror unit at the first position is obtained, and time reversal operation is performed on the signal, and the signal after the time reversal operation is transmitted at the second position; based on the transmission channel information, the spatial distribution of the electric field intensity at the target F and the neighborhood thereof is obtained, and a time reversal focusing point is obtained. A time reversal focusing model of the moving time reversal mirror is established, and the influence of the moving time reversal node on the focusing effect is analyzed and evaluated.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic energy focusing technology, and in particular to a simulation method for time-reversal focusing performance under a motion time-reversal mirror. Background Technology

[0002] Time-reversal (TRM) technology possesses spatiotemporal focusing characteristics, enabling adaptive focusing at the target location in complex multipath scattering environments and reconstructing the signal in the form of an inverted wave. System response time refers to the time it takes for the system to process the signal. Existing simulation studies on the focusing effect of TRM all assume that the time-reversal mirror (TRM) is stationary; for static targets and TRM units, the system response time does not affect the focusing effect.

[0003] However, in practical applications, time-reversal mirror antennas, except for base station antennas, are mostly in motion. For moving time-reversal mirrors, the system's response time determines the position of the time-reversal signal returned by the time-reversal mirror unit, thus affecting the focusing results. Therefore, for electromagnetic energy focusing applications under various motion states, such as mobile distributed radar detection, distributed electronic jamming, and distributed communication, existing evaluation systems for time-reversal focusing effects are not applicable to real-world situations.

[0004] In short, to meet practical engineering needs, it is necessary to establish a time-reversal focusing model for motion-time inversion nodes and analyze and evaluate the impact of response time on focusing performance under motion-time inversion node conditions. In practical engineering applications, the system's response time can be adjusted based on the analysis and evaluation results to achieve the best focusing effect. Summary of the Invention

[0005] Based on the above analysis, the embodiments of the present invention aim to provide a simulation method for time-reversal focusing performance under a moving time-reversal mirror, in order to solve the problem that existing simulation research methods for time-reversal focusing effects cannot simulate and analyze the time-reversal focusing effect under a moving time-reversal mirror, cannot meet the needs of actual engineering, and therefore cannot effectively guide engineering applications.

[0006] On the one hand, a simulation method for time-reversal focusing performance under a motion-time-reversal mirror includes the following steps:

[0007] Target F emits a radiation signal;

[0008] The receiving channel information between the time-reversal mirror unit at the first position and the target is acquired; the transmitting channel information between the time-reversal mirror unit at the second position and each point in the neighborhood of the target is acquired; wherein, the time-reversal mirror unit moves at a speed v and arrives at the second position from the first position after time T;

[0009] Based on the received channel information, the signal received by the time reversal mirror unit at the first position is obtained, and a time reversal operation is performed on it;

[0010] The time reversal mirror unit transmits the signal after the time reversal operation from the second position;

[0011] The electric field intensity of the target F and its neighborhood Ω received by the time-reversal signal is calculated based on the transmission channel information; the spatial distribution of the electric field intensity in the target and its neighborhood is obtained to obtain the time-reversal focal point.

[0012] Specifically, the time-reversal mirror unit has a unit pattern function of: The antenna element, i represents the i-th time-reversal mirror element.

[0013] Specifically, the time-reversal operation on the radiation signal is as follows: the radiation signal is reversed in the time domain, or the radiation signal is conjugate in the frequency domain.

[0014] Specifically, for free space and simple environments, the channel impulse response of the received channel information and the transmitted channel information is obtained by integrating the Green's function.

[0015] Furthermore, the radiation signal is a single-frequency sinusoidal signal, and the electric field intensity of the target F and its neighborhood Ω receiving the time-reversed signal is:

[0016]

[0017] Where N is the number of time-reversal mirror units; n i A is a unit vector representing the direction of the electric field; F Indicates the amplitude of the radiated signal. These represent the angular frequency and initial phase of the radiated signal, respectively; A i This represents the gain of the time-reversal mirror unit after time reversal and re-emission. This is the directionality function corresponding to the signal received by the time-reversal mirror unit. The directionality function corresponding to the signal emitted by the time-reversal mirror unit; l Fi This represents the transmission path of the radiated signal from target point F to the time-reversal mirror unit when it is in its first position. 1i (r) represents the signal transmission path of the time-reversal mirror unit when it moves to the second position and retransmits the signal.

[0018] The radiation signal is a Gaussian pulse signal, and the electric field intensity of the target F and its neighborhood Ω receiving the time-reversed signal is:

[0019]

[0020] Where N is the number of time-reversal mirror units; α is the parameter of the Gaussian pulse signal.

[0021] Furthermore, the target region includes M targets and their neighborhoods, the number of time-reversal mirror units is N, and the electric field intensity of the time-reversal focused signal of the entire target region is the superposition of the electric field intensity of the time-reversal signals of N time-reversal mirrors within each target and its neighborhood.

[0022] On the other hand, embodiments of the present invention provide a method for obtaining the optimal response time affecting focusing performance of a motion-time inversion system based on the above-described method, comprising the following steps:

[0023] Step SS1: Use the above simulation method to obtain the spatial distribution of the electric field intensity of the time-reversed focused signal;

[0024] Step SS2: Based on the spatial distribution of the electric field intensity in Step SS1, determine whether the focal point of the time-reversal signal is within the equivalent direction-finding accuracy and equivalent positioning accuracy; if the determination result is yes, proceed to Step SS3; if the determination result is no, proceed to Step SS4.

[0025] Step SS3: After expanding the time T by a preset factor, re-acquire the spatial distribution of the electric field intensity in the target and its neighborhood, until the judgment result of step SS2 is negative, then at the set time T j Compared to the previous time T j-1 Determine the optimal response time between these points;

[0026] Step SS4: After reducing the time T by a preset factor, re-acquire the spatial distribution of the electric field intensity in the target and its neighborhood until the judgment result of step SS2 is yes, then at the set time T j Compared to the previous time T j-1 Determine the optimal response time between these points.

[0027] Specifically, the preset multiplier is set according to the computer performance and the requirements of the specific scenario for the accuracy of the optimal response time.

[0028] Specifically, the initial trial value of time T is selected based on the motion speed of the time inversion mirror in the specific time inversion system.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] 1. Compared with existing simulation methods for time reversal focusing effects on static targets and time reversal mirrors, this invention establishes a time reversal focusing model for a moving time reversal mirror, which can simulate and model the time reversal focusing effect when the time reversal mirror is in motion. Therefore, it is more practical for actual engineering projects where antennas are mostly in motion.

[0031] 2. The method for obtaining the critical response time of a motion time inversion mirror that affects focusing performance, provided by this invention, can observe and analyze the impact of the response time of various motion time inversion systems on the time inversion focusing effect, and further obtain the optimal response time that changes the focusing effect. This optimal response time provides a reference for the range of reasonable control system response time in practical applications.

[0032] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0033] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0034] Figure 1 A flowchart illustrating the simulation method for time-reversal focusing performance under a motion-time-reversal mirror;

[0035] Figure 2 A schematic diagram showing the relative positions of the target and the time-reversal mirror unit;

[0036] Figure 3 A schematic diagram illustrating the focusing effect of a single-frequency transmitted signal and a TRM moving at speeds of 80 km / h, 130 km / h, 500 km / h, and 2000 km / h, respectively.

[0037] Figure 4 A schematic diagram illustrating the focusing effect of a Gaussian transmitted signal and a TRM moving at speeds of 80 km / h, 130 km / h, 500 km / h, and 2000 km / h, respectively.

[0038] Figure 5 A schematic diagram showing the focusing effect at different response times for a single-frequency transmitted signal and a TRM moving at 80 km / h.

[0039] Figure 6 A schematic diagram showing the focusing effect at different response times for a single-frequency transmitted signal and a TRM moving at 130 km / h.

[0040] Figure 7 A schematic diagram illustrating the focusing effect at different response times for a single-frequency transmitted signal and a TRM moving at 500 km / h.

[0041] Figure 8A schematic diagram showing the focusing effect at different response times for a single-frequency transmitted signal and a TRM moving at 2000 km / h.

[0042] Figure 9 A schematic diagram showing the focusing effect of a Gaussian-transmitted signal and a TRM moving at 80 km / h under different response times;

[0043] Figure 10 A schematic diagram showing the focusing effect at different response times when a Gaussian signal is emitted and a TRM moves at 130 km / h.

[0044] Figure 11 A schematic diagram showing the focusing effect at different response times when a Gaussian signal is emitted and the TRM moves at 500 km / h.

[0045] Figure 12 A schematic diagram showing the focusing effect at different response times when a Gaussian signal is emitted and the TRM moves at 2000 km / h. Detailed Implementation

[0046] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0047] One specific embodiment of the present invention discloses a simulation method for time-reversal focusing performance under a motion-time-reversal mirror, such as... Figure 1 As shown, it includes the following steps:

[0048] Target F emits a radiation signal;

[0049] The receiving channel information between the time-reversal mirror unit at the first position and the target is acquired; the transmitting channel information between the time-reversal mirror unit at the second position and each point in the neighborhood of the target is acquired; wherein, the time-reversal mirror unit moves at a speed v and arrives at the second position from the first position after time T;

[0050] Based on the received channel information, the signal received by the time reversal mirror unit at the first position is obtained, and a time reversal operation is performed on it;

[0051] The time reversal mirror unit transmits the signal after the time reversal operation from the second position;

[0052] The electric field intensity of the target F and its neighborhood Ω received by the time-reversal signal is calculated based on the transmission channel information; the spatial distribution of the electric field intensity in the target and its neighborhood is obtained to obtain the time-reversal focal point.

[0053] Specifically, the time-reversal mirror element has the element pattern function as follows: The antenna element, i represents the i-th time-reversal mirror element.

[0054] The principles and theoretical basis of the above methods are as follows:

[0055] The radiation signal of a single target is a single-frequency signal:

[0056]

[0057] Among them, A F ω represents the amplitude of the radiated signal, and ω represents the angular frequency. Indicates the initial phase.

[0058] After being transmitted through the channel, it is S i The received signal is:

[0059]

[0060] Where, r i =(x i ,y i ,z i ) and r F =(x F ,y F ,z F ) represent the positions of the i-th time-reversal mirror unit and the target point F, respectively. Let be the channel impulse response function between the i-th time-reversal mirror and the target.

[0061] Performing a time-reversal operation on the radiation signal specifically involves reversing the radiation signal in the time domain (i.e., flipping it to S). Fi (-t)), or, take the conjugate in the frequency domain.

[0062] The radiated signal is received by the time-reversal mirror unit and then re-reversed to obtain the re-transmitted signal:

[0063]

[0064] Among them, A i This represents the gain of the time-reversal mirror unit after time reversal and re-emission.

[0065] The electric field of this signal within the neighborhood Ω of the target point F can be expressed as:

[0066]

[0067] Where r = (x, y, z) represents the coordinates of a point within the neighborhood Ω. S represents i The directional function.

[0068] S TRiSubstituting (t) into the above electric field, we get:

[0069]

[0070] Furthermore, for free space and simple environments, the impulse response of the aforementioned receiving channel model can be obtained by integrating the Green's function.

[0071] Specifically, in free space or simple environments, the channel response is a Green's function, which can be obtained by performing an inverse Fourier transform. and

[0072]

[0073]

[0074] Among them, l Fi This indicates the radiated signal from target point F to S. i The transmission path This represents the wave speed along its path; similarly, l i (r) indicates that the signal retransmitted after time reversal processing originates from S. i The transmission path to a point within the neighborhood Ω. The wave speed along its path.

[0075] Considering a simple environment where the atmospheric channel remains constant during transmission and reception, the following results can be assumed:

[0076]

[0077] Furthermore, since there is l at the target point F i (r)=l Fi Therefore, we get:

[0078]

[0079] That is, at the target point F, the transmission channel is used. and receiving channel They are completely reciprocal.

[0080] Will and Substitute E i From the expression for (r,t), we obtain the general case of the electric field expression at a point within the neighborhood Ω of the target point F:

[0081]

[0082] Furthermore, if we assume that the atmospheric channel is time-invariant, then we have:

[0083]

[0084] The sum of the electric field strengths of the N time-reversal mirror antenna elements is:

[0085]

[0086] Let r = r F Substituting into the above equation, we get:

[0087]

[0088] As can be seen from the above formula, through time inversion, the transmitted signals of different time inversion mirror unit antenna arrays are superimposed with the same phase at the target point F.

[0089] Furthermore, each target point can undergo time-reversal focusing operations following the steps described above. By superimposing the time-reversal focused fields generated by each time-reversal mirror unit onto a neighborhood containing all target points, the time-reversal focused field in the case of multiple targets can be obtained.

[0090]

[0091] Where M and N are the number of phased array antenna elements and time-reversal mirror elements of the receiver, respectively, and i and j are their indices.

[0092] Furthermore, the time-reversal mirror unit, initially at position A, receives the signal and performs a time-reversal operation. It then moves at velocity v and reaches position B (a distance Tv from point A) after time T, at which point it transmits the time-reversed signal. The channel response when the time-reversal mirror unit transmits the signal becomes, i.e., the Green's function becomes:

[0093]

[0094]

[0095] Among them, l Fi This indicates the radiated signal from target point F to S. i The transmission path from (original location A) Indicates the wave speed along its path; l 1i (r) indicates that the signal retransmitted after time reversal processing originates from S. i Move to position B, the transmission path from point B to a point within the neighborhood Ω. The wave speed along its path. i =(x i ,y i ,z i ) represents the position (point A) of the i-th time-reversal mirror unit before it moves, r F =(x F ,yF Z F ) represents the position of target point F, r 1i =(x 1i ,y 1i ,z 1i Let (x, y, z) represent the position (point B) of the i-th time-reversal mirror unit after it has moved, and let r = (x, y, z) represent the coordinates of a point in the neighborhood Ω.

[0096] For example, for a single-frequency sinusoidal transmitted signal, the sum of the electric field strengths of the N time-reversal mirror antenna elements is:

[0097]

[0098] in, This is the directionality function corresponding to the signal received by the time-reversal mirror unit. This is the directional function corresponding to the signal emitted by the time-reversal mirror unit.

[0099] For example, for a Gaussian pulse transmitted signal, the sum of the electric field strengths of the N time-reversal mirror antenna elements is:

[0100]

[0101] In practical implementation, this invention employs a time-reversal mirror method, arranging a limited number of antenna elements for receiving / transmitting signals within a certain angular range. Appropriate placement of the time-reversal mirror elements can achieve excellent time-reversal focusing effects. A schematic diagram illustrating the relative positions of the target and the time-reversal mirror is shown below. Figure 2 As shown, the present invention sets the target and the time-reversal mirror unit on the same plane.

[0102] The time-reversal mirror unit consists of 36 omnidirectional antennas with a gain of 3dBi, uniformly distributed in a ring on the XOY plane with a radius of 30km. The target is located at its center (0, 0, 0), and the target point neighborhood Ω is taken as: x∈[-5λ, 5λ], y∈[-5λ, 5λ], where λ is the operating wavelength.

[0103] To verify the effectiveness of the simulation method of this invention, two different types of transmitted signals are used to analyze the time reversal focusing effect of the time reversal mirror unit at different motion speeds.

[0104] First, for example, the transmitted signal is a single-frequency signal of 3 GHz, and the time interval T is set to 0.1 ms. For time-reversal mirror units moving randomly at a speed of 80 kmph on the ground, 130 kmph in the air, 500 kmph in the air, and 2000 kmph in the air, the time-reversal electric field values ​​of 36 time-reversal mirror units are calculated according to the simulation method of this invention. The obtained electric field distribution diagram is shown below. Figure 3 As shown.

[0105] Depend on Figure 3 It can be seen that for time reversal systems moving at speeds of 80kmph and 130kmph, transmitting the time reversal operation signal 0.1ms after movement results in a better focusing effect; while for time reversal systems moving at speeds of 500kmph and 2000kmph, transmitting the time reversal operation signal 0.1ms after movement results in a poorer focusing effect.

[0106] Next, for example, the transmitted signal is a Gaussian signal with a center frequency of 200MHz and a bandwidth of 30MHz. For time-reversal mirror units moving randomly at speeds of 80kmph on the ground, 130kmph in the air, 500kmph in the air, and 2000kmph in the air, with time intervals all set to 1μs, the time-reversal electric field values ​​of 36 time-reversal mirror units are calculated according to the simulation method of this invention. The obtained electric field distribution diagram is shown below. Figure 4 As shown.

[0107] Depend on Figure 4 It can be seen that for time reversal systems moving at speeds of 80kmph, 130kmph, 500kmph, and 2000kmph, the focusing effect is good when the time reversal operation signal is emitted 1μs after the movement, proving that the shorter the response time, the weaker the impact on the focusing effect.

[0108] The simulation method described in this invention can obtain the time-reversal focusing results corresponding to the motion state of the time-reversal system. It can also observe the influence of the motion state of the time-reversal mirror unit on the time-reversal focusing effect, thus verifying the feasibility and effectiveness of the method and providing guidance for practical time-reversal technology engineering.

[0109] On the other hand, embodiments of the present invention provide a method for obtaining the optimal response time affecting focusing performance of a motion-time inversion system based on the above-described method, comprising the following steps:

[0110] Step SS1: Use the above simulation method to obtain the spatial distribution of the electric field intensity of the time-reversed focused signal;

[0111] Step SS2: Based on the spatial distribution of the electric field intensity in Step SS1, determine whether the focal point of the time-reversal signal is within the equivalent direction-finding accuracy and equivalent positioning accuracy; if the determination result is yes, proceed to Step SS3; if the determination result is no, proceed to Step SS4.

[0112] Step SS3: After expanding the time T by a preset factor, re-acquire the spatial distribution of the electric field intensity in the target and its neighborhood, until the judgment result of step SS2 is negative, then at the set time T j Compared to the previous time T j-1 Determine the optimal response time between these points;

[0113] Step SS4: After reducing the time T by a preset factor, re-acquire the spatial distribution of the electric field intensity in the target and its neighborhood until the judgment result of step SS2 is yes, then at the set time T j Compared to the previous time T j-1 Determine the optimal response time between these points.

[0114] In practical implementation, this invention employs a time-reversal mirror method, arranging a limited number of antenna elements for receiving / transmitting signals within a certain angular range. Appropriate placement of the time-reversal mirror elements can achieve excellent time-reversal focusing effects. A schematic diagram illustrating the relative positions of the target and the time-reversal mirror is shown below. Figure 2 As shown, the present invention sets the target and the time-reversal mirror unit on the same plane.

[0115] The time-reversal mirror unit consists of 36 omnidirectional antennas with a gain of 3dBi, uniformly distributed in a ring on the XOY plane with a radius of 30km. The target is located at its center (0, 0, 0), and the target point neighborhood Ω is taken as: x∈[-5λ, 5λ], y∈[-5λ, 5λ], where λ is the operating wavelength.

[0116] Specifically, the preset multiplier is set according to the computer performance and the requirements of the specific scenario for the accuracy of the optimal response time. In this invention, the preset multiplier is set to 10 times.

[0117] Specifically, the initial trial value of time T is selected according to the motion speed of the time inversion mirror in the specific time inversion system. In this invention, the initial trial value of T is set to 1 ns.

[0118] To verify the effectiveness of the simulation method of the present invention, two different types of transmission signals were still taken, and the maximum response time that changes the focusing effect at this speed was obtained using the above method.

[0119] First, for example, the transmitted signal is a single-frequency signal of 3GHz, the initial value of the time interval T is set to 1ns, and the preset multiple is 10 times. The time inversion electric field values ​​of 36 time inversion mirror units under different speeds and different time intervals are calculated according to the simulation method in Example 1.

[0120] For a time-reversal mirror unit moving along a random path at a speed of 80 kmph on the ground, electric field distribution maps corresponding to different response times were obtained as follows: Figure 5 As shown. By Figure 5 It can be seen that the focusing effect deteriorates as the response time T increases. When T ≤ 0.1 ms, the signal can be accurately focused on the target point. When T ≥ 1 ms, the focused image becomes cluttered, indicating that the maximum response time has been exceeded, resulting in poor focusing effect. Therefore, for a time-reversal mirror unit moving along a random path at a speed of 80 kmph on the ground, the optimal response time is between 0.1 ms and 1 ms.

[0121] For time-reversal mirror units moving randomly along a path at a speed of 130 km / h in the air, such as small drones, electric field distribution maps corresponding to different response times are obtained, as shown below. Figure 6 As shown. By Figure 6 It can be seen that when T≤0.1ms, the signal can be accurately focused on the target point. When T≥1ms, the focused image becomes cluttered, indicating that the maximum response time has been exceeded, resulting in poor focusing performance. Therefore, for a time-reversal mirror unit moving randomly along a path at a speed of 130kmph in the air, the optimal response time is between 0.1ms and 1ms.

[0122] For time-reversal nodes moving at 500 km / h in the air along random paths, such as rotorcraft, medium to large UAVs, and transport aircraft, electric field distribution maps corresponding to different response times are obtained, as shown below. Figure 7 As shown. By Figure 7 It can be seen that when T≤0.1ms, the signal can be accurately focused on the target point. When T≥1ms, the focused image becomes cluttered, indicating that the maximum response time has been exceeded, resulting in poor focusing performance. Therefore, for a time-reversal mirror unit moving randomly along a path at a speed of 500kmph in the air, the optimal response time is between 0.1ms and 1ms.

[0123] For time-reversal nodes moving at 2000 km / h along random paths in the air, such as fixed-wing aircraft and fighter jets, electric field distribution maps corresponding to different response times are obtained, as shown below. Figure 8 As shown. By Figure 8It can be seen that when T≤0.01ms, the signal can be accurately focused on the target point. When T≥0.1ms, the focused image becomes cluttered, indicating that the maximum response time has been exceeded, resulting in poor focusing performance. Therefore, for a time-reversal mirror unit moving randomly along a path at a speed of 2000kmph in the air, the optimal response time is between 0.01ms and 0.1ms.

[0124] Next, for example, the transmitted signal is a Gaussian signal with a center frequency of 200MHz and a bandwidth of 30MHz. The initial value of the time interval T is set to 1ns, and the preset multiple is 10 times. The time inversion electric field values ​​of 36 time inversion mirror units at different speeds and time intervals are calculated according to the simulation method in Example 1.

[0125] For a time-reversal mirror unit moving along a random path at a speed of 80 kmph on the ground, electric field distribution maps corresponding to different response times were obtained as follows: Figure 9 As shown. By Figure 9 It can be seen that the focusing effect deteriorates as the response time T increases. When T ≤ 0.01 s, the signal can be accurately focused on the target point. When T ≥ 0.1 s, the focused image becomes cluttered, indicating that the maximum response time has been exceeded, resulting in poor focusing effect. Therefore, for a time-reversal mirror unit moving along a random path at a speed of 80 kmph on the ground, the optimal response time is between 0.01 s and 0.1 s.

[0126] For time-reversal mirror units moving randomly along a path at a speed of 130 km / h in the air, such as small drones, electric field distribution maps corresponding to different response times are obtained, as shown below. Figure 10 As shown. By Figure 10 It can be seen that when T≤1ms, the signal can be accurately focused on the target point. When T≥10ms, the focused image becomes cluttered, indicating that the maximum response time has been exceeded, resulting in poor focusing performance. Therefore, for a time-reversal mirror unit moving randomly along a path at a speed of 130kmph in the air, the optimal response time is between 1ms and 10ms.

[0127] For time-reversal nodes moving at 500 km / h in the air along random paths, such as rotorcraft, medium to large UAVs, and transport aircraft, electric field distribution maps corresponding to different response times are obtained, as shown below. Figure 11 As shown. By Figure 11 It can be seen that when T≤0.1ms, the signal can be accurately focused on the target point. When T≥1ms, the focused image becomes cluttered, indicating that the maximum response time has been exceeded, resulting in poor focusing performance. Therefore, for a time-reversal mirror unit moving randomly along a path at a speed of 500kmph in the air, the optimal response time is between 0.1ms and 1ms.

[0128] For time-reversal nodes moving at 2000 km / h along random paths in the air, such as fixed-wing aircraft and fighter jets, electric field distribution maps corresponding to different response times are obtained, as shown below. Figure 12 As shown. By Figure 12 It can be seen that when T≤0.1ms, the signal can be accurately focused on the target point. When T≥1ms, the focused image becomes cluttered, indicating that the maximum response time has been exceeded, resulting in poor focusing performance. Therefore, for a time-reversal mirror unit moving randomly along a path at a speed of 2000kmph in the air, the optimal response time is between 0.1ms and 1ms.

[0129] Using the above method, the maximum acceptable response time of the time inversion system moving at different speeds can be obtained. This maximum response time can be used as a reference in actual engineering design, that is, to further control the response time of the system to achieve a good focusing effect.

[0130] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0131] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A simulation method for time-reversal focusing performance under a motion-time-reversal mirror, characterized in that, Includes the following steps: Target F emits a radiation signal; The receiving channel information between the time-reversal mirror unit at the first position and the target is acquired; the transmitting channel information between the time-reversal mirror unit at the second position and each point in the target's neighborhood is acquired; wherein, the time-reversal mirror unit has a speed The movement occurs, and after time T, the movement moves from the first position to the second position; Based on the received channel information, the signal received by the time reversal mirror unit at the first position is obtained, and a time reversal operation is performed on it; The time reversal mirror unit transmits the signal after the time reversal operation from the second position; Calculate the target F and its neighborhood based on the transmission channel information. The electric field intensity of the received time-reversal signal is obtained; the spatial distribution of the electric field intensity in the target and its neighborhood is acquired to obtain the time-reversal focal point. The radiation signal is a single-frequency sinusoidal signal, and the pattern function of the time-reversal mirror unit is... Target F and its neighborhood The electric field strength of the received time-reversal signal is: The radiation signal is a Gaussian pulse signal, and the target F and its neighborhood are... The electric field strength of the received time-reversal signal is: Where N is the number of time-reversal mirror units; A unit vector representing the direction of the electric field; These are the parameters of a Gaussian pulse signal; These represent the angular frequency and initial phase of the radiated signal, respectively. Indicates the amplitude of the radiated signal; This represents the gain of the time-reversal mirror unit after time reversal and re-emission. This is the directionality function corresponding to the signal received by the time-reversal mirror unit. This is the directional function corresponding to the signal emitted by the time-reversal mirror unit; This represents the transmission path of the radiated signal from target point F to when the time-reversal mirror unit is in its first position. This indicates the signal transmission path for the time-reversal mirror unit to move to the second position and re-transmit the signal.

2. The simulation method for time-reversal focusing performance under a motion-time-reversal mirror according to claim 1, characterized in that, The time-reversal mirror unit has a unit pattern function of: Antenna elements, Indicates the first One time-reversal mirror unit.

3. The simulation method for time-reversal focusing performance under a motion-time-reversal mirror according to claim 1, characterized in that, Performing a time-reversal operation on the radiation signal includes: reversing the radiation signal in the time domain, or taking the conjugate of the radiation signal in the frequency domain.

4. The simulation method for time-reversal focusing performance under a motion-time-reversal mirror according to claim 2, characterized in that, For free space and simple environments, the channel impulse response of the received channel information and the transmitted channel information is obtained by integrating the Green's function.

5. The simulation method for time-reversal focusing performance under a motion-time-reversal mirror according to claim 1, characterized in that, The target region contains M targets and their neighborhoods, and the number of time-reversal mirror units is N. The electric field intensity of the time-reversal focused signal of the entire target region is the superposition of the electric field intensity of the time-reversal signals of N time-reversal mirrors within each target and its neighborhood.

6. A method for obtaining the optimal response time affecting focusing performance of a motion-time inversion system based on the method described in claim 1, characterized in that, Includes the following steps: Step SS1: Obtain the spatial distribution of the electric field intensity of the time-reversed focused signal using the method described in claim 1; Step SS2: Determine whether the focal point of the time-reversal signal is within the equivalent direction-finding accuracy and equivalent positioning accuracy based on the spatial distribution of the electric field intensity in Step SS1; if the determination result is yes, proceed to Step SS3. If the result is negative, proceed to step SS4; Step SS3: After expanding the time T by a preset factor, re-acquire the spatial distribution of the electric field intensity in the target and its neighborhood, until the judgment result of step SS2 is negative, then within the set time... Compared to the time set last time Determine the optimal response time between these points; Step SS4: After reducing the time T by a preset factor, re-acquire the spatial distribution of the electric field intensity in the target and its neighborhood until the judgment result of step SS2 is yes, then within the set time... Compared to the time set last time Determine the optimal response time between these points.

7. The method for obtaining the optimal response time affecting focusing performance of a motion-time inversion system according to claim 6, characterized in that, The preset multiplier is set according to the computer performance and the specific scenario's requirements for optimal response time accuracy.

8. The method for obtaining the optimal response time affecting focusing performance of a motion-time inversion system according to claim 6, characterized in that, The initial trial value of time T is selected based on the motion speed of the time inversion mirror in the specific time inversion system.

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