Missile-target intersection echo signal processing method and system based on time domain electromagnetic scattering algorithm

Abstract

The invention discloses a missile-target intersection echo signal processing method and system based on a time domain electromagnetic scattering algorithm, and the method comprises the steps: carrying out the simulation of a fuze dynamic echo signal of a missile-target intersection section through the time domain electromagnetic scattering algorithm, and carrying out the demodulation, matched filtering, Fourier transform and inverse Fourier transform processing of a scattered echo signal on this basis. A target distance Doppler map containing distance information and speed information is obtained, and the problems that time domain near-field scattering modeling of the electrically large-size target under antenna beam irradiation is difficult and target feature information is difficult to obtain in the missile-target intersection process are solved; meanwhile, a modulated Gaussian pulse is adopted as an incident pulse, and a relatively large bandwidth is obtained by utilizing a relatively narrow pulse width, so that the problem of low simulation efficiency is solved, and overlapping of scattered echoes in different pulse repetition periods is also avoided; according to the invention, the target detection, identification and multi-dimensional perception capabilities of a radar system in a missile target intersection scene are significantly improved; the invention also provides a system for realizing the method.

Description

Technical Field

[0001] The present invention relates to the technical field of signal processing, and particularly relates to a method and system for processing echo signals of missile-target intersection based on a time-domain electromagnetic scattering algorithm. Background Art

[0002] In different intersection states, the near-field scattering characteristics of the target and the processing method of radar echo data signals are different, which will affect the detection ability of the radar antenna of the guided weapon for the target. Therefore, the acquisition and signal processing of near-field scattering echo data can provide important data sources and technical supports for optimizing the near-field detection ability of the radar target. For the acquisition of radar echo data, it is far from enough to simply measure the echo data of the target by experimental methods, because the near-field characteristics test of the target is greatly affected by test conditions, environment, polarization, target attitude and positioning accuracy, resulting in extremely high measurement costs, large measurement errors and unsatisfactory repeatability. Especially, it is difficult to obtain the electromagnetic scattering characteristics of non-cooperative targets through measured data.

[0003] With the development of computational electromagnetics and computer technology, electromagnetic scattering simulation has become an important way to obtain radar characteristic information of targets. By simulating the radar echo of the target by computer, a large amount of valuable data can be obtained. The electromagnetic scattering simulation algorithm considers the interaction mechanism between electromagnetic waves and the target. The target echo data obtained based on the electromagnetic scattering model is currently the closest to the measured radar echo data. This accurate echo simulation algorithm overcomes the shortcomings of insufficient experimental measurement data, and has low cost and strong timeliness.

[0004] Computer simulation technologies based on frequency-domain electromagnetic scattering methods mostly generate echoes by combining far-field RCS or scattering coefficients with transmitted pulse signals. However, RCS and scattering coefficients are the far-field scattering characteristics of the target, lacking near-field scattering information, and the phase information is lost in RCS and scattering coefficients. In addition, the simulation of range-Doppler images based on radar echo data usually uses linear frequency modulation continuous wave (LFMCW) as the incident pulse for simulation, resulting in an increase in modeling time and low simulation efficiency.

[0005] Huang Zhiyong (Huang Zhiyong, Fang Jinpeng, Wang Shuang, et al. Wideband Near-Field Echo and Simulation Algorithm Based on Time-Domain High-Frequency Method [J]. Guidance & Fuze, 2024, 45(01): 27-31+37.) proposed a wideband near-field echo and Doppler echo simulation algorithm based on the time-domain high-frequency method. The time-domain physical optics algorithm is used to calculate the time-domain echo of missile-target intersection and process the echo to obtain the Doppler frequency, realizing the fast simulation of wideband near-field dynamic Doppler echo. However, this method only gives the simulation process of the Doppler frequency and does not realize the simulation of the range-Doppler map. Summary of the Invention

[0006] In order to overcome the defects existing in the above-mentioned prior art, the purpose of the present invention is to provide a method and system for processing the echo signal of missile-target encounter based on the time-domain electromagnetic scattering algorithm. The time-domain electromagnetic scattering algorithm is used to simulate the dynamic echo signal of the fuse in the missile-target encounter section. On this basis, the scattered echo signal is successively demodulated, matched filtered, Fourier transformed, and inverse Fourier transformed to obtain the target range-Doppler map containing range information and velocity information, solving the problems of difficult time-domain near-field scattering modeling of large electrically sized targets under the illumination of the antenna beam and difficult acquisition of target feature information during the missile-target encounter process; at the same time, a modulated Gaussian pulse is used as the incident pulse, and a larger bandwidth is obtained by using a narrower pulse width, solving the problem of low simulation efficiency and avoiding the overlap of scattered echoes within different pulse repetition periods; the present invention combines the time-domain electromagnetic scattering algorithm with the signal processing method and applies it to the missile-target encounter scenario, significantly improving the target detection, recognition, and multi-dimensional perception capabilities of the radar system in the missile-target encounter scenario.

[0007] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A method for processing the echo signal of missile-target encounter based on the time-domain electromagnetic scattering algorithm includes:

[0009] Determine the scattered echo matrix during the encounter period between the detector and the detected target;

[0010] Demodulate the scattered echo matrix during the encounter period between the detector and the detected target to obtain the baseband echo signal matrix;

[0011] Perform matched filtering on the baseband echo signal matrix to obtain the frequency-domain matched filtering data matrix at each moment of motion;

[0012] Perform Fourier transform on each column in the frequency-domain matched filtering data matrix to obtain the Doppler-domain data matrix;

[0013] Perform inverse Fourier transform on each row in the Doppler-domain data matrix to obtain the range-Doppler map of the detector and the detected target.

[0014] Further, before determining the scattered echo matrix during the encounter period between the detector and the detected target, a modulated Gaussian pulse is used as the pulse signal emitted by the fuse of the detector to the detected target.

[0015] Further, the determination of the scattered echo matrix during the encounter period between the detector and the detected target specifically includes:

[0016] Determine the encounter time according to the motion parameters of the detector and the detected target;

[0017] Discretely sample the rendezvous movement time to obtain multiple movement moments during the rendezvous movement process;

[0018] Determine the position information of the detector and the detected target at each moment, the attitude information of the detected target, and the beam direction of the detector according to the multiple movement moments;

[0019] Calculate the scattered field of the detected target at each moment by using the time-domain near-field electromagnetic scattering algorithm according to the position information of the detector and the detected target at each moment, the attitude information of the detected target, and the beam pointing of the detector;

[0020] Store the scattered field of the detected target at each moment row by row into a two-dimensional matrix to obtain the scattered echo matrix during the rendezvous time period.

[0021] Further, the specific steps of calculating the scattered field of the detected target at each moment by using the time-domain near-field electromagnetic scattering algorithm according to the position information of the detector and the detected target at each moment, the attitude information of the detected target, and the beam pointing of the detector include:

[0022] Determine the vertex coordinates of the surface elements of the detected target according to the position information and attitude information of the detected target at each moment; the detected target includes multiple surface elements;

[0023] Calculate the time-domain scattered field of each surface element by using the near-field time-domain physical optics algorithm according to the vertex coordinates of the surface elements of the detected target, the position information of the detector, and the beam pointing of the detector;

[0024] Superimpose the time-domain scattered fields of each surface element to obtain the scattered field of the detected target at each moment.

[0025] Further, the specific steps of calculating the time-domain scattered field of each surface element by using the near-field time-domain physical optics algorithm according to the vertex coordinates of the surface elements of the detected target, the position information of the detector, and the beam pointing of the detector include:

[0026] Determine the distance and direction between the surface element of the detected target and the detector according to the vertex coordinates of the surface element of the detected target and the position information of the detector;

[0027] Determine whether the surface element is irradiated by the detector according to the direction between the surface element and the detector, the beam pointing of the detector, and the beam width. If it is irradiated, calculate the scattered field of the surface element, otherwise do not calculate;

[0028] Obtain the time-domain incident field of the surface element by using the time-domain radiation field formula of the detector according to the distance and direction between the surface element and the detector;

[0029] Bring the time-domain incident field of the surface element into the near-field time-domain physical optics integral, and use the local Green's function of the surface element to perform a far-field approximation on the near-field integral to obtain the time-domain scattered field of the surface element.

[0030] Further, the demodulation process of the scattered echo matrix during the intersection period of the detector and the detected target to obtain the baseband echo signal matrix specifically includes:

[0031] Obtain the expression of the scattered echo according to the scattered echo matrix:

[0032]

[0033] Where:

[0034]

[0035] p(t) is the transmitted signal waveform function; * is the convolution operation; δ is the impulse function; t is the movement time; is the direction from the center of the surface element to the scattered field point; r is the position coordinate of the detector antenna; ε is the step function; is the direction from the antenna to the center of the surface element; v i is the vertex of the integration plane; c is the speed of light; A0 is the echo signal amplitude; p (-1) is the first-order integral of p(t); η is the wave impedance of the space where the antenna is located; ρ n is the distance from the antenna to the center of the surface element; R n is the distance from the center of the surface element to the scattered field point; Δv i =v i+1 -v i ; β is the projection of ω on the integration plane; is the unit normal vector of the surface element; J a is the equivalent current density; is the unit dyad; is the first-order integral of J a ; is the second-order integral of J a ;

[0036] Suppose the positions of the detected target and the detector are constant within the pulse repetition period, and the pulse repetition period is T r , for the nth incident pulse, the distance from the detector to the detected target is R(nT r ), according to Equation (14), express the dynamic echo as:

[0037]

[0038] Where: Replace with R represents the distance between the vertex of the detected target polygon and the receiving antenna;

[0039] Multiply the dynamic echo by the phase factor to obtain the baseband echo signal matrix:

[0040]

[0041] where: ω0 is the carrier angular frequency.

[0042] Furthermore, the specific steps of performing matched filtering on the baseband echo signal matrix to obtain the frequency-domain matched filtering data matrix at each motion moment include:

[0043] Perform Fourier transform on the baseband echo signal matrix to obtain the frequency-domain echo data matrix:

[0044]

[0045] where: ω is the angular frequency; n is the nth incident pulse; T r is the pulse repetition period; A0 is the echo amplitude; j is the imaginary unit; ω0 is the carrier angular frequency; G(jω) is obtained by Fourier transform of the baseband signal of the modulated Gaussian pulse; c is the speed of light;

[0046] In the case where the detector and the detected target move along a straight line, the distance from the detector to the detected target is expressed as:

[0047] R(nT r ) = R0 - V0nT r (19)

[0048] where: R0 is the distance between the detector and the detected target at the initial moment; V0 is the relative speed between the detector and the detected target at the initial moment;

[0049] Set the matched filter as:

[0050]

[0051] Multiply the frequency-domain echo data matrix by the matched filter to obtain the frequency-domain matched filtering data matrix:

[0052]

[0053] where: f0 is the center frequency; f is the frequency within the bandwidth.

[0054] Furthermore, the Doppler domain data matrix specifically includes:

[0055]

[0056] where: ω is the angular frequency; f dis the Doppler frequency; A0 is the echo amplitude; p d is a sinc function; f0 is the center frequency; f is the frequency within the bandwidth; V0 is the relative velocity between the detector and the detected target at the initial moment; c is the speed of light; R0 is the distance between the detector and the detected target at the initial moment.

[0057] Further, the specific process of obtaining the range-Doppler map of the detector and the detected target by performing the inverse Fourier transform on each row of the Doppler-domain data matrix includes:

[0058] If the frequency f within the bandwidth is less than one-tenth of the center frequency f0, then it can be approximated that:

[0059] (f0 + f)V0 ≈ f0V0 (23) where: V0 is the relative velocity between the detector and the detected target at the initial moment;

[0060] Performing the range inverse Fourier transform on the Doppler-domain data matrix and combining with Equation (23), the expression of the range-Doppler map of the detector and the detected target is obtained:

[0061]

[0062] where: t is the movement moment; f d is the Doppler frequency; A0 is the echo amplitude; p d is a sinc function; f d is the Doppler frequency; c is the speed of light; p r is a sinc function; R0 is the distance between the detector and the detected target at the initial moment; j is the imaginary unit; is the exponential term, which is an additional phase term.

[0063] A missile-target encounter echo signal processing system based on the time-domain electromagnetic scattering algorithm includes:

[0064] Scattered echo matrix determination module: determining the scattered echo matrix during the encounter period between the detector and the detected target;

[0065] Baseband echo signal matrix calculation module: demodulating the scattered echo matrix during the encounter period between the detector and the detected target to obtain the baseband echo signal matrix;

[0066] Frequency-domain matched filtering data matrix calculation module: performing matched filtering processing on the baseband echo signal matrix to obtain the frequency-domain matched filtering data matrix at each movement moment;

[0067] Doppler-domain data matrix calculation module: performing Fourier transform on each column of the frequency-domain matched filtering data matrix to obtain the Doppler-domain data matrix;

[0068] Range-Doppler map calculation module: Perform inverse Fourier transform on each row of the data matrix in the Doppler domain to obtain the range-Doppler map of the detector and the detected target.

[0069] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0070] 1. The present invention simulates the scattered echo signal during the entire missile-target encounter period through the time-domain electromagnetic scattering algorithm, processes the scattered echo signal, and obtains the range-Doppler during the encounter movement period between the detector and the detected target, effectively solving problems such as the difficulty in modeling the time-domain near-field scattering of large electrically large targets under the illumination of the antenna beam and the difficulty in obtaining target feature information, and significantly improving the target detection, recognition, and multi-dimensional perception capabilities of the radar system.

[0071] 2. Aiming at the problem of low signal simulation efficiency when using linear frequency modulation continuous wave impulse as the radar transmitting wave, the present invention uses a modulated Gaussian pulse as the incident pulse, which can obtain a larger bandwidth with a relatively narrow pulse width, solves the problem of low simulation efficiency, and also avoids the overlap of scattered echo signals within different pulse repetition periods.

[0072] In summary, the present invention simulates the fuse dynamic echo signal in the missile-target encounter section through the time-domain electromagnetic scattering algorithm, and on this basis, demodulates, matched filters, Fourier transforms, and performs inverse Fourier transform on the scattered echo signal in sequence to obtain the target range-Doppler map containing range information and velocity information, solving the problems of the difficulty in modeling the time-domain near-field scattering of large electrically large targets under the illumination of the antenna beam and the difficulty in obtaining target feature information during the missile-target encounter process; at the same time, using a modulated Gaussian pulse as the incident pulse, a larger bandwidth is obtained with a relatively narrow pulse width, solving the problem of low simulation efficiency, and also avoiding the overlap of scattered echo signals within different pulse repetition periods; the present invention combines the time-domain electromagnetic scattering algorithm with the signal processing method and applies it to the missile-target encounter scenario, significantly improving the target detection, recognition, and multi-dimensional perception capabilities of the radar system in the missile-target encounter scenario. Description of the Drawings

[0073] Figure 1 It is a flowchart of the method for processing the missile-target encounter echo signal based on the time-domain electromagnetic scattering algorithm.

[0074] Figure 2 It is a flowchart of the simulation of the fuse dynamic echo signal in the missile-target encounter section.

[0075] Figure 3 It is a schematic diagram of the detector beam irradiation element.

[0076] Figure 4 It is a schematic diagram of the missile geometric model.

[0077] Figure 5It is the missile range-Doppler image. Specific embodiments

[0078] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0079] In view of the requirements for obtaining and analyzing the near-field target echo data during the missile-target encounter at the end of the guidance of modern precision-guided weaponry, as well as the practical problems of high cost for obtaining near-field echo data by experimental measurement means, lack of measurement data, and great difficulty in obtaining the characteristic information of non-cooperative targets, the present invention proposes a method for processing the echo signal of missile-target encounter based on the time-domain electromagnetic scattering algorithm. See Figure 1 , specifically as follows:

[0080] Determine the scattering echo matrix during the encounter period between the detector and the detected target; as Figure 2 shown, in this embodiment, in a computer simulation scenario, appropriate antenna parameters and encounter motion parameters are selected. According to the encounter motion model, the antenna motion time and the number of transmitted pulse trains are determined. The motion time is discretely sampled using the quasi-static method. According to the change of time during the encounter motion, the geometric information and relative position model of the target and the antenna at each moment are established, and the time-domain near-field electromagnetic scattering simulation algorithm is used to calculate the scattering field at this moment, and finally it is stored in a two-dimensional matrix to obtain the scattering echo matrix;

[0081] Before determining the scattering echo matrix during the encounter period, linear frequency modulation continuous wave (LFMCW) is usually used as the incident pulse for simulation, which increases the modeling time and results in low simulation efficiency; the present invention considers using a modulated Gaussian pulse as the pulse signal transmitted by the fuse of the detector to the detected target, which can obtain a larger bandwidth with a relatively narrow pulse width, solves the problem of low simulation efficiency, and also avoids the overlap of scattering echoes within different pulse repetition periods; the present invention takes the detector as a missile as an example. There is a fuse on the missile, and an antenna is arranged inside the fuse.

[0082] During the missile-target encounter, the modulated Gaussian pulse sequence transmitted by the fuse of the detector in this embodiment is:

[0083]

[0084] where: ω0 is the carrier angular frequency; * is the convolution operation; P τ0 / 2 (t) is a modulated Gaussian pulse with a time width of τ0; δ is the impulse function; N is the number of pulses; t is the motion moment; T is the pulse repetition period;

[0085] The present invention calculates the echo signal during the missile-target encounter motion with the quasi-static idea. It is assumed that the fuse and the target are in a static state within a single pulse period. At this time, the near-field time-domain physical optics algorithm is used to calculate the scattered echo signal of the pulse incident on the target. The echo signal of each pulse is stored row by row in a two-dimensional data matrix, and then the two-dimensional scattered echo matrix within the entire missile-target encounter section can be obtained.

[0086] Taking the nth pulse as an example, according to Equation (1), the expression of the nth pulse can be written as:

[0087]

[0088] At this time, the fuse of the detector and the detected target move forward at their respective speeds by V f nT and V o nT; where V f is the speed of the fuse of the detector; V o is the speed of the detected target; it is assumed that the fuse of the detector and the detected target are located at P f and P o respectively. Taking p n (t) as the excitation pulse, the corresponding scattered echo can be calculated by using the near-field time-domain physical optics method The fuse echo signal within the entire missile-target encounter section can be written as where M is the number of pulses emitted by the fuse within the missile-target encounter section.

[0089] The determination of the scattered echo matrix during the encounter time period between the detector and the detected target specifically includes:

[0090] Determine the encounter motion time according to the motion parameters of the detector and the detected target;

[0091] The motion parameters in this embodiment include path parameters and speed parameters; the path parameters include the route of the detector moving from the initial position to the termination position. According to the path parameters of the detector, the motion distance of the detector can be determined; the speed parameter is the motion speed of the detector, and the encounter motion time of the detector can be obtained by dividing the motion distance of the detector by the motion speed of the detector.

[0092] Perform discrete sampling on the encounter motion time to obtain multiple motion moments during the encounter motion process; the discrete sampling in this embodiment is to collect the encounter motion time at a fixed interval period, converting the continuous time signal into a discrete time series, which is convenient for subsequent signal processing and transmission;

[0093] Determine the position information of the detector and the detected target corresponding to each moment, the attitude information of the detected target, and the beam direction of the detector according to the multiple motion moments;

[0094] In this embodiment, according to the motion speed v0 of the detector and the motion time t at each moment, the motion distance of the detector can be calculated as x = v0t, and thus the position information of the detector at each moment can be obtained; during the motion process, the detector beam always irradiates the detected target, so the beam direction of the detector at each moment is the connection direction between the detector position and the center of the detected target.

[0095] The position information and attitude information of the detected target can be regarded as being obtained by translating and rotating the detected target at the initial moment; the position information of the detected target can be obtained through the translation matrix [T], and the attitude information can be obtained through the first rotation matrix [R]. Then, the center point coordinates of the detected target before and after motion can be defined as:

[0096] P t ′ = [T][R]P0′ (3)

[0097] where, P t ′ = [P t ,1] T is the target center point coordinate matrix at the motion time t; P0′ = [P0,1] is the target center point coordinate matrix at the initial moment; P t is the center point coordinate at the motion time t after motion; P0 is the center point coordinate at the initial moment;

[0098] The translation matrix [T] is:

[0099]

[0100] where: S(t) = [S x (t), S y (t), S z (t)] is the displacement vector of the detected target at the time t;

[0101] The first rotation matrix [R] is:

[0102]

[0103] where: θ(t) = [θ x (t), θ y (t), θ z (t)] is the rotation angle of the detected target around the x, y, and z axes at the time t;

[0104] According to the position information of the detector and the detected target corresponding to each moment, the attitude information of the detected target, and the beam direction of the detector, the scattering field of the detected target at each moment is calculated by using the time-domain near-field electromagnetic scattering algorithm;

[0105] Further, calculating the scattering field of the detected target at each moment by using the time-domain near-field electromagnetic scattering algorithm according to the position information of the detector and the detected target at each moment, the attitude information of the detected target, and the beam pointing of the detector specifically includes:

[0106] According to the position information and attitude information of the detected target at each moment, determine the vertex coordinates of the surface elements of the detected target; the detected target includes a plurality of surface elements;

[0107] In this embodiment, the vertex coordinates of the surface elements of the detected target at each moment can be obtained according to the position coordinates, attitude information, and local vertex coordinates of the surface elements of the detected target at each moment, where the attitude information is the direction vectors of the three coordinate axes of the local coordinate system where the detected target is located, which are respectively The unit vector of the x-axis of the local coordinate system at time t, The unit vector of the y-axis of the local coordinate system at time t, The unit vector of the z-axis of the local coordinate system at time t.

[0108] Assume that the position coordinate of the detected target at the initial moment is P0, and the vertex coordinates of the surface elements at the initial moment are V0, then the local vertex coordinates of the surface elements are V' = V0 - P0, at the initial moment The vertex coordinates of the surface elements of the detected target at time t can be written as:

[0109]

[0110] Where: P t Is the position coordinate of the detected target at time t;

[0111] The second rotation matrix [R]' is:

[0112]

[0113] Where: θ(t) = [θ x (t), θ y (t), θ z (t)] Is the angle of rotation of the detected target around the x, y, and z axes at time t;

[0114] According to the vertex coordinates of the surface elements of the detected target, the position information of the detector, and the beam pointing of the detector, calculate the time-domain scattering field of each surface element by using the near-field time-domain physical optics algorithm;

[0115] Further, calculating the time-domain scattering field of each surface element by using the near-field time-domain physical optics algorithm according to the vertex coordinates of the surface elements of the detected target, the position information of the detector, and the beam pointing of the detector specifically includes:

[0116] Determine the distance and direction between the surface element of the detected target and the detector according to the surface element vertex coordinates of the detected target and the position information of the detector;

[0117] Let the surface element vertex coordinates of the detected target be P(x, y, z), the position of the detector be P0(x0, y0, z0), and the direction between the surface element of the detected target and the detector is defined as:

[0118]

[0119] The distance between the surface element of the detected target and the detector is defined as:

[0120]

[0121] Determine whether the surface element is irradiated by the detector according to the direction between the surface element and the detector, the beam pointing and beam width of the detector. If it is irradiated, calculate the scattered field of the surface element, otherwise do not calculate;

[0122] As Figure 3 shown, θ is the angle of the half beam width of the detector, and α is the angle between the line connecting the center point of the surface element and the detector and the main beam ray of the detector. When the angle α is less than the half beam width θ of the detector, the surface element is irradiated by the detector; when the angle α is greater than the half beam width θ of the detector, the surface element is not irradiated by the detector.

[0123] According to the distance and direction between the surface element and the detector, obtain the time-domain incident field of the surface element by using the time-domain radiation field formula of the detector;

[0124] Substitute the time-domain incident field of the surface element into the near-field time-domain physical optics integral, and use the local Green's function of the surface element to perform a far-field approximation on the near-field integral to obtain the time-domain scattered field of the surface element.

[0125] When using the near-field time-domain physical optics algorithm (NFTDPO) in this embodiment to calculate the scattered field of the detected target, it is first necessary to determine the incident field of the detected target, and the incident field of the detected target is the radiation field of the antenna; first, give the time-domain radiation field expression of the antenna:

[0126]

[0127] Among them: η is the wave impedance of the space where the antenna is located; ρ is the distance from the antenna to the radiation field point; p(t) is the transmitted signal waveform function; represents the inverse Fourier transform; j is the imaginary unit; k is the wave number; is the vector current moment; * is the convolution operation; c is the speed of light; δ is the impulse function; t is the movement time;

[0128] Based on Equation (10), in order to improve the efficiency of near-field integration, the far-field approximation of the near-field integration is processed using the local Green's function of the surface element. Within a certain allowable error range, the NFTDPO integral can be simplified to a closed expression through the time-domain Gordon integral formula; the finally obtained scattered field expression is:

[0129]

[0130] Where:

[0131]

[0132]

[0133] ρ n is the distance from the antenna to the center of the surface element; is the direction from the antenna to the center of the surface element; R n is the distance from the center of the surface element to the scattered field point; is the direction from the center of the surface element to the scattered field point; J a is the equivalent current density; is the unit dyad; is the first-order integral of J a ; is the second-order integral of J a ; is the unit dyad; r is the position coordinate of the detector antenna; r s is the position coordinate of the receiving antenna; r n is the position coordinate of the center point of the surface element; ΔS is the surface element area; Δv i =v i+1 -v i , β is the projection of ω on the integration plane, v i is the vertex of the integration plane; is the unit normal vector of the surface element;

[0134] The time-domain scattered fields of each surface element are superimposed to obtain the scattered field of the detected target at each moment.

[0135] The scattered fields of the detected target at each moment are stored row by row in a two-dimensional matrix to obtain the scattered echo matrix during the intersection time period.

[0136] Through the above simulation of the fuze dynamic echo signal in the missile-target intersection section, efficient, accurate and stable scattered echoes are provided for the subsequent signal processing.

[0137] To solve the problems of difficult time-domain near-field scattering modeling for electrically large-sized targets and difficult acquisition of target characteristic information, based on obtaining the scattered echo matrix, the present invention successively performs demodulation, matched filtering, Fourier transform, and inverse Fourier transform on the scattered echo matrix during the intersection time period to obtain the range-Doppler map during the intersection movement time period of the detector and the detected target; specifically as follows:

[0138] Perform demodulation processing on the scattered echo matrix during the intersection time period of the detector and the detected target to obtain the baseband echo signal matrix;

[0139] Further, the performing demodulation processing on the scattered echo matrix during the intersection time period of the detector and the detected target to obtain the baseband echo signal matrix includes:

[0140] Obtain the expression of the scattered echo according to the scattered echo matrix:

[0141]

[0142] Where:

[0143]

[0144] p(t) is the transmitted signal waveform function; * is the convolution operation; δ is the impulse function; t is the movement time; is the direction from the surface element center to the scattering field point; r is the detector antenna position coordinate; ε is the step function; is the direction from the antenna to the surface element center; v i is the vertex of the integration plane; c is the speed of light; A0 is the echo signal amplitude; p (-1) is the first-order integral of p(t); η is the wave impedance of the space where the antenna is located; ρ n is the distance from the antenna to the surface element center; R n is the distance from the surface element center to the scattering field point; Δv i =v i+1 -v i ; β is the projection of ω on the integration plane; is the unit normal vector of the surface element; J a is the equivalent current density; is the unit dyad; is the first-order integral of J a ; is the second-order integral of J a ;

[0145] Based on the quasi-static strategy, it is assumed that the positions of the detected target and the detector are constant within the pulse repetition period, and the pulse repetition period is T r , for the nth incident pulse, the distance from the detector to the detected target is R(nTr ), according to Equation (14), the dynamic echo is expressed as:

[0146]

[0147] Where: replacing with R represents the distance between the vertices of the polygon of the detected target and the receiving antenna;

[0148] Multiply the dynamic echo by the phase factor to obtain the baseband echo signal matrix:

[0149]

[0150] Where: ω0 is the carrier angular frequency.

[0151] Perform matched filtering on the baseband echo signal matrix to obtain the frequency-domain matched filtering data matrix at each motion moment;

[0152] Furthermore, the performing matched filtering on the baseband echo signal matrix to obtain the frequency-domain matched filtering data matrix at each motion moment specifically includes:

[0153] Perform Fourier transform on the baseband echo signal matrix to obtain the frequency-domain echo data matrix:

[0154]

[0155] Where: ω is the angular frequency; n is the nth incident pulse; T r is the pulse repetition period; A0 is the echo amplitude; j is the imaginary unit; ω0 is the carrier angular frequency; G(jω) is obtained by Fourier transform of the baseband signal of the modulated Gaussian pulse; c is the speed of light;

[0156] In the case where the detector and the detected target move along a straight line, the distance from the detector to the detected target is expressed as:

[0157] R(nT r ) = R0 - V0nT r (19)

[0158] Where: R0 is the distance between the detector and the detected target at the initial moment; V0 is the relative speed between the detector and the detected target at the initial moment;

[0159] Since a modulated Gaussian pulse is used as the incident pulse, it is necessary to improve the matched filter. The improved matched filter can greatly improve the calculation efficiency while ensuring the image quality; therefore, the matched filter is set as:

[0160]

[0161] Multiply the frequency-domain echo data matrix by the matched filter to obtain a frequency-domain matched-filtered data matrix:

[0162]

[0163] where: f0 is the center frequency; f is the frequency within the bandwidth.

[0164] Perform a Fourier transform on each column of the frequency-domain matched-filtered data matrix to obtain a Doppler-domain data matrix;

[0165] Further, the Doppler-domain data matrix specifically includes:

[0166]

[0167] where: ω is the angular frequency; f d is the Doppler frequency; A0 is the echo amplitude; p d is the sinc function; f0 is the center frequency; f is the frequency within the bandwidth; V0 is the relative velocity between the detector and the detected target at the initial moment; c is the speed of light; R0 is the distance between the detector and the detected target at the initial moment.

[0168] In this embodiment, since the transmitted signal used is a broadband pulse, the frequency in Equation (22) can take any value within the bandwidth; this means that by performing one matched filtering and one Fourier transform, the Doppler frequency corresponding to any electromagnetic wave frequency within the entire bandwidth can be obtained; for example, by setting f = 0, the Doppler frequency corresponding to the center frequency f0 can be obtained.

[0169] Perform an inverse Fourier transform on each row of the Doppler-domain data matrix to obtain the range-Doppler map of the detector and the detected target.

[0170] Further, the step of performing an inverse Fourier transform on each row of the Doppler-domain data matrix to obtain the range-Doppler map of the detector and the detected target specifically includes:

[0171] If the frequency f within the bandwidth is less than one-tenth of the center frequency f0, then it can be approximated that:

[0172] (f0 + f)V0 ≈ f0V0 (23)

[0173] where: V0 is the relative velocity between the detector and the detected target at the initial moment;

[0174] Perform an inverse range Fourier transform on the Doppler-domain data matrix, and then combine with Equation (23) to obtain the expression of the range-Doppler map of the detector and the detected target:

[0175]

[0176] Where: t is the movement time; f d is the Doppler frequency; A0 is the echo amplitude; p d is a sinc function; f d is the Doppler frequency; c is the speed of light; p r is a sinc function; R0 is the distance between the detector and the detected target at the initial moment; j is the imaginary unit; is the exponential term, which is an additional phase term.

[0177] By processing the scattered echo matrix multiple times as described above, a range-Doppler map containing range information and velocity information is obtained, providing the radar system with multi-dimensional target perception capabilities.

[0178] A missile-target encounter echo signal processing system based on a time-domain electromagnetic scattering algorithm, comprising:

[0179] Scattered echo matrix determination module: determining the scattered echo matrix during the encounter period between the detector and the detected target;

[0180] Baseband echo signal matrix calculation module: demodulating the scattered echo matrix during the encounter period between the detector and the detected target to obtain the baseband echo signal matrix;

[0181] Frequency-domain matched filtering data matrix calculation module: performing matched filtering on the baseband echo signal matrix to obtain the frequency-domain matched filtering data matrix at each movement time;

[0182] Doppler-domain data matrix calculation module: performing Fourier transform on each column of the frequency-domain matched filtering data matrix to obtain the Doppler-domain data matrix;

[0183] Range-Doppler map calculation module: performing inverse Fourier transform on each row of the Doppler-domain data matrix to obtain the range-Doppler map of the detector and the detected target.

[0184] The application effect of the present invention will be described in detail below in combination with simulation experiments.

[0185] Simulate the range-Doppler image during the missile-target encounter movement according to the above technical solution; as Figure 4 shown, the size of the missile is 6.8m × 2.6m × 1.6m; the pulse center frequency is f0 = 10GHz, and the bandwidth is f b = 1GHz. The dipole antenna is located 10m away from the center of the missile, the relative velocity between the antenna and the missile is V0 = 800m / s, and the pulse repetition period is T r = 5×10 3 ns. Figure 5It is the range-Doppler simulation image of the missile. It can be seen from the figure that the strong scattering point of the target is located at 800 m / s on the velocity axis, which is consistent with the moving speed of the target. On the range axis, different peak points represent different strong scattering centers of the target, ranging from 11 meters to 18 meters, which is consistent with the size of the target on the x-axis. This proves that the method proposed by the present invention can accurately obtain the target velocity and range information by using the scattered echo.

[0186] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be covered by the protection scope of the present invention.

Claims

1. A method for processing echo signals of missile-target encounter based on time-domain electromagnetic scattering algorithm, characterized in that: Including: Determine the scattered echo matrix during the intersection period between the detector and the detected target; Demodulate the scattered echo matrix during the intersection period between the detector and the detected target to obtain the baseband echo signal matrix; Perform matched filtering on the baseband echo signal matrix to obtain the frequency-domain matched filtering data matrix at each movement moment; Perform Fourier transform on each column in the frequency-domain matched filtering data matrix to obtain the Doppler-domain data matrix; Perform inverse Fourier transform on each row in the Doppler-domain data matrix to obtain the range-Doppler map of the detector and the detected target.

2. A method for processing echo signals of missile-target encounter based on time-domain electromagnetic scattering algorithm according to claim 1, characterized in that: Before determining the scattered echo matrix during the intersection period between the detector and the detected target, use a modulated Gaussian pulse as the pulse signal emitted by the detector's fuse towards the detected target.

3. A method for processing the echo signal of missile-target encounter based on the time-domain electromagnetic scattering algorithm according to claim 1, characterized in that: The determination of the scattered echo matrix during the intersection period between the detector and the detected target specifically includes: Determine the time of the intersection movement according to the movement parameters of the detector and the detected target; Perform discrete sampling on the intersection movement time to obtain multiple movement moments during the intersection movement process; Determine the position information of the detector and the detected target at each moment, the attitude information of the detected target, and the beam direction of the detector according to the multiple movement moments; Calculate the scattered field of the detected target at each moment using the time-domain near-field electromagnetic scattering algorithm according to the position information of the detector and the detected target at each moment, the attitude information of the detected target, and the beam direction of the detector; Store the scattered field of the detected target at each moment row by row into a two-dimensional matrix to obtain the scattered echo matrix during the intersection period.

4. A method for processing echo signals of missile-target encounter based on time-domain electromagnetic scattering algorithm according to claim 3, characterized in that: The calculation of the scattered field of the detected target at each moment using the time-domain near-field electromagnetic scattering algorithm according to the position information of the detector and the detected target at each moment, the attitude information of the detected target, and the beam direction of the detector specifically includes: Determine the vertex coordinates of the surface elements of the detected target according to the position information and attitude information of the detected target at each moment; the detected target includes multiple surface elements; Calculate the time-domain scattered field of each surface element using the near-field time-domain physical optics algorithm according to the vertex coordinates of the surface elements of the detected target, the position information of the detector, and the beam direction of the detector; Superimpose the time-domain scattered fields of each surface element to obtain the scattered field of the detected target at each moment.

5. A method for processing echo signals of missile-target intersection based on time-domain electromagnetic scattering algorithm according to claim 4, characterized in that: The calculation of the time-domain scattered field of each surface element using the near-field time-domain physical optics algorithm according to the vertex coordinates of the surface elements of the detected target, the position information of the detector, and the beam direction of the detector specifically includes: Determine the distance and direction between the surface element of the detected target and the detector according to the vertex coordinates of the surface element of the detected target and the position information of the detector; Determine whether the surface element is illuminated by the detector according to the direction between the surface element and the detector, the beam direction of the detector, and the beam width. If it is illuminated, calculate the scattered field of the surface element, otherwise do not calculate; Obtain the time-domain incident field of the surface element using the time-domain radiation field formula of the detector according to the distance and direction between the surface element and the detector; Substitute the time-domain incident field of the surface element into the near-field time-domain physical optics integral, and perform far-field approximation processing on the near-field integral using the local Green's function of the surface element to obtain the time-domain scattered field of the surface element.

6. The method for processing the echo signal of missile-target encounter based on the time-domain electromagnetic scattering algorithm according to claim 1, characterized in that: Demodulating the scattering echo matrix during the intersection period between the detector and the detected target to obtain the baseband echo signal matrix specifically includes: Obtaining the expression of the scattering echo according to the scattering echo matrix: Where: p(t) is the transmitted signal waveform function; * is the convolution operation; δ is the impulse function; t is the movement time; is the direction from the bin center to the scattering field point; r is the position coordinate of the detector antenna; ε is the step function; is the direction from the antenna to the bin center; v i is the vertex of the integration plane; c is the speed of light; A0 is the echo signal amplitude; p (-1) is the first-order integral of p(t); η is the wave impedance of the space where the antenna is located; ρ n is the distance from the antenna to the bin center; R n is the distance from the bin center to the scattering field point; Δv i = v i+1 - v i ; β is the projection of ω on the integration plane; is the unit normal vector of the bin; J a is the equivalent current density; is the unit dyad; is the first-order integral of J a ; is the second-order integral of J a ; Assume that the positions of the detected target and the detector are constant within the pulse repetition period, and the pulse repetition period is T r , for the nth incident pulse, the distance from the detector to the detected target is R(nT r ). According to Equation (14), the dynamic echo is expressed as: Wherein: Replace with R represents the distance between the vertex of the polygon of the detected target and the receiving antenna; Multiply the dynamic echo with the phase factor to obtain the baseband echo signal matrix: Where: ω0 is the carrier angular frequency.

7. A method for processing echo signals of missile-target encounter based on time-domain electromagnetic scattering algorithm according to claim 1 or 2, characterized in that: Performing a matched filtering process on the baseband echo signal matrix to obtain the frequency-domain matched filtering data matrix at each movement moment specifically includes: Performing a Fourier transform on the baseband echo signal matrix to obtain the frequency-domain echo data matrix: Where: ω is the angular frequency; n is the nth incident pulse; T r is the pulse repetition period; A0 is the echo amplitude; j is the imaginary unit; ω0 is the carrier angular frequency; G(jω) is obtained by Fourier transforming the baseband signal of the modulated Gaussian pulse; c is the speed of light; In the case where the detector and the detected target move along a straight line, expressing the distance from the detector to the detected target as: R(nT r ) = R0 - V0nT r (19) Where: R0 is the distance between the detector and the detected target at the initial moment; V0 is the relative velocity between the detector and the detected target at the initial moment; Setting the matched filter as: Multiplying the frequency-domain echo data matrix by the matched filter to obtain the frequency-domain matched filtering data matrix: Where: f0 is the center frequency; f is the frequency within the bandwidth.

8. A method for processing echo signals of missile-target encounter based on time-domain electromagnetic scattering algorithm according to claim 1, characterized in that: The Doppler domain data matrix specifically includes: Where: ω is the angular frequency; f d is the Doppler frequency; A0 is the echo amplitude; p d is the sinc function; f0 is the center frequency; f is the frequency within the bandwidth; V0 is the relative velocity between the detector and the detected target at the initial moment; c is the speed of light; R0 is the distance between the detector and the detected target at the initial moment.

9. A method for processing the echo signal of missile-target encounter based on the time-domain electromagnetic scattering algorithm according to claim 1, characterized in that: Performing an inverse Fourier transform on each row in the Doppler domain data matrix to obtain the range-Doppler map of the detector and the detected target specifically includes: If the frequency f within the bandwidth is less than one-tenth of the center frequency f0, then it can be approximated: (f0 + f)V0 ≈ f0V0 (23) Where: V0 is the relative velocity between the detector and the detected target at the initial moment; Performing an inverse range Fourier transform on the Doppler domain data matrix and combining with Equation (23) to obtain the expression of the range-Doppler map of the detector and the detected target: where: t is the movement time; f d is the Doppler frequency; A0 is the echo amplitude; p d is a sinc function; f d is the Doppler frequency; c is the speed of light; p r is a sinc function; R0 is the distance between the detector and the detected target at the initial moment; j is the imaginary unit; is an exponential term and is an additional phase term.

10. A missile-target intersection echo signal processing system based on a time-domain electromagnetic scattering algorithm, characterized in that: Including: Scattering echo matrix determination module: determining the scattering echo matrix during the intersection period between the detector and the detected target; Baseband echo signal matrix calculation module: demodulating the scattering echo matrix during the intersection period between the detector and the detected target to obtain the baseband echo signal matrix; Frequency-domain matched filtering data matrix calculation module: performing a matched filtering process on the baseband echo signal matrix to obtain the frequency-domain matched filtering data matrix at each movement moment; Doppler domain data matrix calculation module: performing a Fourier transform on each column in the frequency-domain matched filtering data matrix to obtain the Doppler domain data matrix; Range-Doppler map calculation module: performing an inverse Fourier transform on each row in the Doppler domain data matrix to obtain the range-Doppler map of the detector and the detected target.

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