Time-sensitive moving target multi-beam joint focusing method, storage medium and electronic device

Abstract

The application provides a time-sensitive moving target multi-beam joint focusing method, a storage medium and an electronic device, and relates to the technical field of radars.A linear processing process is formed by a constructed generalized sliding window matching function and a multi-beam focusing matching function, the problem that a weak moving target is easily submerged in noise due to the fact that a non-linear method is used to compensate for energy defocusing of the moving target in the prior art method, resulting in serious energy loss, is overcome, and the performance of focusing on the weak moving target is improved.Furthermore, the initial beam time of the moving target, the target cross-beam time, the scene center slant range, the radial velocity, the radial acceleration and the radial jerk obtained by searching are used for compensating for additional azimuth window modulation due to the fact that the moving target crosses multiple beams and complex range-azimuth migration in a single beam, and precise focusing of the weak moving target is realized.

Description

Technical Field

[0001] This invention relates to the field of radar technology, and specifically to a time-sensitive moving target multi-beam joint focusing method, storage medium, and electronic device. Background Technology

[0002] In general scenarios, increasing observation time and employing long-term coherent accumulation techniques can effectively improve radar's ability to detect small / stealthy moving targets.

[0003] However, with the emergence of stealth aircraft and near-space hypersonic vehicles and other weak moving targets, radar needs to consider the cross-beam migration of moving targets when detecting them. In order to accumulate the echo energy of weak moving targets over a long observation period, two problems need to be solved: First, the severe defocusing of target energy caused by range migration and Doppler migration; second, the accumulation of target echo energy dispersed in different beams (grating lobes) to improve the radar's detection performance for these targets.

[0004] Currently, there is no effective way to solve the technical problem of multi-beam target echo signal accumulation. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a time-sensitive moving target multi-beam joint focusing method, storage medium, and electronic device, which solves the problem of multi-beam target echo signal accumulation.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] Firstly, a method for joint focusing of time-sensitive moving targets using multiple beams is provided, the method comprising:

[0010] Transmit a linear frequency modulated signal and acquire the first echo signal reflected by the moving target;

[0011] The first echo signal is demodulated, pulse compressed, and subjected to a fast Fourier transform along the range direction in sequence to obtain the second echo signal;

[0012] The second echo signal is subjected to complex range and azimuth migration and modulation window compensation to obtain the third echo signal;

[0013] The fourth echo signal is obtained by compensating for the range migration of the third echo signal using Keystone transform; and the fifth echo signal is obtained by performing inverse fast Fourier transform along the range direction and fast Fourier transform along the azimuth direction on the fourth echo signal.

[0014] Peak retrieval is performed on the fifth echo signal to obtain the estimated values ​​of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target.

[0015] Based on the estimated values ​​of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target, the estimated values ​​of the peak distance position, the azimuth Doppler frequency variable of the moving target signal, the radial velocity of the moving target, and the slant distance of the scene center are obtained.

[0016] Based on the obtained estimates, the range and azimuth migration within the beam of the second echo signal are corrected, and the echo energy of moving targets dispersed in different beams is accumulated to obtain the multi-beam focusing accumulation and radial range estimation results.

[0017] Furthermore, the transmitted linear frequency modulated signal is represented as:

[0018]

[0019] The first echo signal reflected by the moving target is represented as:

[0020]

[0021] Among them, s t (t) represents the transmitted linear frequency modulated signal;

[0022] s r (t,t m This represents the first echo signal reflected by the moving target;

[0023] rect represents a rectangular window function;

[0024] t represents the distance in time;

[0025] T P This represents the pulse width of the linear frequency modulated signal transmitted by the radar.

[0026] exp represents an exponent with the natural constant e as its base;

[0027] j represents the symbol for the imaginary unit;

[0028] K r It is the modulation frequency of a linear frequency modulation signal;

[0029] f c This indicates the carrier frequency of the linear frequency modulated signal transmitted by the radar.

[0030] tm Indicates location and time.

[0031] R s (t m )≈R0+b1t m +b2t m 2 +b3t m 3 Indicates instantaneous slant distance;

[0032] R0 represents the slant distance from the scene center;

[0033] b1 represents the radial velocity of the moving target;

[0034] b2 represents the radial acceleration of the moving target;

[0035] b3 represents the radial jerk of the moving target;

[0036] t inq This indicates the moment when a moving target enters the q-th beam of the radar, where q = 1, 2, ..., N; and N represents the number of beams.

[0037] c represents the speed of light.

[0038] Furthermore, the step of sequentially demodulating, pulse compressing, and performing a fast Fourier transform along the range direction on the first echo signal to obtain the second echo signal includes:

[0039] S2.1, Regarding the received first echo signal s r (t,t m The signal is demodulated to obtain the demodulated echo signal.

[0040] S2.2, Demodulated echo signal Pulse compression processing is performed to obtain the pulse-compressed echo signal s. base (t,t m );

[0041] S2.3, The echo signal s after pulse compression base (t,t m Perform a Fast Fourier Transform (FFT) along the range direction to obtain the range-frequency domain-slow time domain moving target echo signal after the FFT, denoted as the second echo signal.

[0042] And the second echo signal Represented as:

[0043]

[0044] in,

[0045] f represents the distance frequency;

[0046] B represents the bandwidth of the transmitted linear frequency modulated signal.

[0047] Furthermore, the process of performing complex range and azimuth migration and modulation window compensation on the second echo signal to obtain the third echo signal includes:

[0048] S3.1 Constructing the generalized sliding window matching function H gm (f,t) m ;t inq , t inq+1 b2, b3), and the generalized sliding window matching function H gm Represented as:

[0049]

[0050] in,

[0051] ΔT q+1，q =t inq+1 -t inq This represents the duration of time it takes for a moving target to pass through the q-th beam;

[0052] S3.2, Apply the generalized sliding window matching function H gm (f,t) m ;t inq , t inq+1 b2, b3) and the second echo signal Multiplying these together yields the third echo signal s1(f,t) after compensation for higher-order distance and azimuth migration. m The third echo signal is represented as:

[0053]

[0054] in,

[0055] Indicates the start time of the q-th sliding window;

[0056] This indicates the duration of the window used by the q-th sliding window operation.

[0057] Furthermore, the process of compensating for the range migration of the third echo signal using Keystone transform to obtain the fourth echo signal, and then performing an inverse Fast Fourier Transform (FSFT) along the range direction and an FFT along the azimuth direction to obtain the fifth echo signal, includes:

[0058] S4.1 Substitute the Keystone transform expression into the third echo signal s1(f, t) m The fourth echo signal s2(f,t) is obtained from the signal.τ ), and the echo signal of the fourth moving target s2(f,t) τ ) is represented as:

[0059]

[0060] Among them, t τ Represents the slow-time variable after the Keystone transformation;

[0061] S4.2, Regarding the fourth echo signal s2(f,t) τ The fifth echo signal is obtained by performing an inverse Fast Fourier Transform along the range direction and a Fast Fourier Transform along the azimuth direction. And the fifth echo signal Represented as;

[0062]

[0063] in, The azimuth Doppler frequency variable represents the signal of a moving target.

[0064] Furthermore, the peak retrieval operation on the fifth echo signal to obtain estimates of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target includes:

[0065]

[0066] in,

[0067] Peak indicates peak search operation;

[0068] KT represents the Keystone transformation operation;

[0069] IFT f This represents the inverse Fourier transform of the distance;

[0070] This represents an estimate of the initial beam time of a moving target;

[0071] This represents an estimate of the time it takes for a moving target to cross the beam.

[0072] This represents an estimate of the radial acceleration of a moving target.

[0073] This represents an estimate of the radial jerk of a moving target.

[0074] Matching value representing the radial acceleration of a moving target

[0075] The matching value represents the radial jerk of a moving target.

[0076] Furthermore, the process of obtaining estimates of peak distance position, azimuth Doppler frequency variable of the moving target signal, radial velocity of the moving target, and slant distance of the scene center based on estimates of the initial beam time, cross-beam time, radial acceleration, and radial jerk of the moving target includes:

[0077]

[0078] in,

[0079] This represents the estimated location of the peak distance;

[0080] The estimated value of the azimuth Doppler frequency variable representing the signal of a moving target;

[0081] Based on and The estimated value of the scene center slope distance is calculated. and the estimated radial velocity of the moving target

[0082] Furthermore, the method of correcting the range and azimuth migration within the beam of the second echo signal based on the obtained estimates, while accumulating the echo energy of moving targets dispersed in different beams, yields multi-beam focusing accumulation and radial range estimation results, including:

[0083] S6.1 Construct a multibeam focusing matching function, and the multibeam focusing matching function is expressed as:

[0084]

[0085] S6.2 Matching the multibeam focusing function With the second echo signal Multiplying these components yields the sixth echo signal s4(f,t) after distance and azimuth migration compensation and modulation window adjustment. m );

[0086] S6.3, Regarding the sixth echo signal s4(f,t) m Perform inverse Fast Fourier Transform (FFT) along the range direction and FFT along the azimuth direction to obtain the multibeam focusing accumulation and radial range estimation results.

[0087] Secondly, a storage medium is provided that stores a computer program for time-sensitive moving target multi-beam co-focusing, wherein the computer program causes a computer to execute the above-described time-sensitive moving target multi-beam co-focusing method.

[0088] Secondly, an electronic device is provided, comprising:

[0089] One or more processors;

[0090] Memory; and

[0091] One or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs including methods for performing the time-sensitive moving target multibeam co-focusing method described above.

[0092] (III) Beneficial Effects

[0093] This invention provides a time-sensitive moving target multi-beam co-focusing method, a storage medium, and an electronic device. Compared with the prior art, it has the following advantages:

[0094] 1) This invention uses a new radar transmission system, namely, a space-based distributed detection platform with fully coherent transmission and reception to detect moving targets. Its purpose is to effectively improve the radar's ability to detect small / stealthy targets by increasing the observation time and using long-term coherent accumulation technology.

[0095] 2) Since the generalized sliding window matching function and multi-beam focusing matching function constructed in this invention are linear processing procedures, they overcome the problem that existing methods use nonlinear methods to compensate for the energy defocusing of moving targets, resulting in severe energy loss and making weak moving targets easily submerged in noise. This improves the performance of the space-based distributed detection platform with fully coherent transmission and reception for focusing on weak moving targets.

[0096] 3) Because the present invention compensates for the additional azimuth window modulation caused by the moving target crossing multiple beams and the complex range and azimuth migration within a single beam by searching for the initial beam time of the moving target, the target cross-beam time, the slant distance of the scene center, the radial velocity, the radial acceleration and the radial jerk, the moving target achieves precise focusing of weak moving targets.

[0097] 4) Since the present invention performs moving target parameter estimation after coherent cumulative focusing processing, it overcomes the problem that the parameter estimation performance of existing methods is severely affected by noise, resulting in a serious decline in parameter estimation performance under low SNR conditions, and improves the performance of ground weak moving target parameter estimation under low SNR conditions. Attached Figure Description

[0098] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0099] Figure 1 This is a flowchart of the present invention;

[0100] Figure 2 This is a schematic diagram showing the distribution characteristics of multibeam target signals in fast range time and slow azimuth time.

[0101] Figure 3 This is the result of pulse compression processing of the echo signal;

[0102] Figure 4 The result of noise removal from the target signal pulse compression;

[0103] Figure 5 The Doppler spectral distribution results for the target;

[0104] Figure 6 The result is a noise-free Doppler spectrum distribution;

[0105] Figure 7 The initial time matching result of the target signal;

[0106] Figure 8 The matching result for the target signal processing window length;

[0107] Figure 9 The result is the target radial acceleration matching.

[0108] Figure 10 To estimate the target velocity parameters;

[0109] Figure 11 3D image of the multi-beam joint focusing result;

[0110] Figure 12 This is a 2D image of the multi-beam joint focusing result. Detailed Implementation

[0111] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0112] This application provides a time-sensitive moving target multi-beam joint focusing method, storage medium, and electronic device, which solves the problem of multi-beam target echo signal accumulation.

[0113] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0114] Example 1:

[0115] like Figure 1 As shown, this invention provides a time-sensitive moving target multi-beam joint focusing method, which includes:

[0116] Transmit a linear frequency modulated signal and acquire the first echo signal reflected by the moving target;

[0117] The first echo signal is demodulated, pulse compressed, and subjected to a fast Fourier transform along the range direction in sequence to obtain the second echo signal;

[0118] The second echo signal is subjected to complex range and azimuth migration and modulation window compensation to obtain the third echo signal;

[0119] The fourth echo signal is obtained by compensating for the range migration of the third echo signal using Keystone transform; and the fifth echo signal is obtained by performing inverse fast Fourier transform along the range direction and fast Fourier transform along the azimuth direction on the fourth echo signal.

[0120] Peak retrieval is performed on the fifth echo signal to obtain the estimated values ​​of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target.

[0121] Based on the estimated values ​​of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target, the estimated values ​​of the peak distance position, the azimuth Doppler frequency variable of the moving target signal, the radial velocity of the moving target, and the slant distance of the scene center are obtained.

[0122] Based on the obtained estimates, the range and azimuth migration within the beam of the second echo signal are corrected, and the echo energy of moving targets dispersed in different beams is accumulated to obtain the multi-beam focusing accumulation and radial range estimation results.

[0123] The beneficial effects of this embodiment are:

[0124] 1) This invention uses a new radar transmission system, namely, a space-based distributed detection platform with fully coherent transmission and reception to detect moving targets. Its purpose is to effectively improve the radar's ability to detect small / stealthy targets by increasing the observation time and using long-term coherent accumulation technology.

[0125] 2) Since the generalized sliding window matching function and multi-beam focusing matching function constructed in this invention are linear processing procedures, they overcome the problem that existing methods use nonlinear methods to compensate for the energy defocusing of moving targets, resulting in severe energy loss and making weak moving targets easily submerged in noise. This improves the performance of the space-based distributed detection platform with fully coherent transmission and reception for focusing on weak moving targets.

[0126] 3) Because the present invention compensates for the additional azimuth window modulation caused by the moving target crossing multiple beams and the complex range and azimuth migration within a single beam by searching for the initial beam time of the moving target, the target cross-beam time, the slant distance of the scene center, the radial velocity, the radial acceleration and the radial jerk, the moving target achieves precise focusing of weak moving targets.

[0127] 4) Since the present invention performs moving target parameter estimation after coherent cumulative focusing processing, it overcomes the problem that the parameter estimation performance of existing methods is severely affected by noise, resulting in a serious decline in parameter estimation performance under low SNR conditions, and improves the performance of ground weak moving target parameter estimation under low SNR conditions.

[0128] The implementation process of the embodiments of the present invention will be described in detail below:

[0129] Assume the radar platform of the geometric detection model of the moving target has a height of H and a velocity of v. p The moving target starts from point a(0, y). p , 0) accelerate to another point b; where,

[0130] v a and a a These are azimuth velocity and acceleration, respectively.

[0131] v r and a r These represent velocity and acceleration in the distance direction, respectively.

[0132] The formula for calculating the slope distance R0 at the scene center is as follows:

[0133]

[0134] The formula for calculating the radial velocity b1 of a moving target is as follows:

[0135]

[0136] The formula for calculating the radial acceleration b2 of a moving target is as follows:

[0137]

[0138] The formula for calculating the radial jerk b3 of a moving target is as follows:

[0139]

[0140] Taking the equivalent radar system with three beams as an example, the distribution characteristics of the echo signal from a moving target in terms of range (fast time) and azimuth (slow time) are as follows: Figure 2 As shown, the radar observation time is from t0 to t1, and the moving target is at time t0. in1 When a moving target enters the equivalent observation beam of the radar system, at t in1 Time to t ou1 The moving target passes through the first grating lobe beam on the left in the diagram at time t. in2 Time to t ou2 The moving target is constantly passing through the main lobe beam at t in3 Time to t ou3 It always passes through the first grating lobe beam on the right side of the diagram.

[0141] The above analysis reveals that the echo signal only contains the echo signal of a moving target when the radar illuminates it; that is, in the image, the echo signal [t] is present. in1 , t ou1 ]、[t in2 , t ou2 ]、[t in3 , t ou3 The time period contains moving target signals; other times only contain background signals such as noise.

[0142] Therefore, the time-sensitive moving target multi-beam joint focusing method of this embodiment includes:

[0143] S1, transmit linear frequency modulated signal s t (t), and acquire the first echo signal s reflected by the moving target. t (t,t m ).

[0144] Specifically, a distributed space-based radar is used to transmit a linear frequency modulated signal and receive the echo signal reflected back from a moving target in the detection area as the first echo signal. After array aperture optimization and aperture synthesis processing, it can be equivalent to the detection performance of a single-base digital multi-beam sparse array platform.

[0145] Transmitted linear frequency modulated signal s t (t) is represented as:

[0146]

[0147] The first echo signal s reflected by the moving target r (t,t m ) is represented as:

[0148]

[0149] in,

[0150] rect represents a rectangular window function;

[0151] t represents the distance in time;

[0152] T P This represents the pulse width of the linear frequency modulated signal transmitted by the radar.

[0153] exp represents the exponential operation with the natural constant e as the base;

[0154] j represents the symbol for the imaginary unit;

[0155] K r It is the modulation frequency of a linear frequency modulation signal;

[0156] f c This indicates the carrier frequency of the linear frequency modulated signal transmitted by the radar.

[0157] t m Indicates location and time.

[0158] R s (t m )≈R0+b1t m +b2t m 2 +b3t m 3 The instantaneous slant distance is represented by R0, which represents the slant distance from the scene center; b1 represents the radial velocity of the moving target; b2 represents the radial acceleration of the moving target; and b3 represents the radial jerk of the moving target.

[0159] t inq This indicates the moment when a moving target enters the q-th beam of the radar, where q = 1, 2, ..., N; and N represents the number of beams.

[0160] c represents the speed of light.

[0161] S2, regarding the first echo signal s r (t,t m The second echo signal is obtained by sequentially demodulating, compressing the pulse, and performing a fast Fourier transform along the range direction.

[0162] Specifically, this includes steps S2.1 to S2.3:

[0163] S2.1, Regarding the received first echo signal s r (t,t m The signal is demodulated to obtain the demodulated echo signal.

[0164] Specifically, the demodulated echo signal Represented as:

[0165]

[0166] in,

[0167] This indicates the estimated distance taken in time.

[0168] λ represents the wavelength of the transmitted linear frequency modulated signal.

[0169] S2.2, Demodulated echo signal Pulse compression processing is performed to obtain the pulse-compressed echo signal s. base (t,t m ).

[0170] Specifically, s base (t,t m ) is represented as:

[0171]

[0172] Where sinc represents the singer function and B represents the bandwidth of the transmitted linear frequency modulated signal.

[0173] S2.3, The echo signal s after pulse compression base (t,t m Perform a Fast Fourier Transform (FFT) along the range direction to obtain the range-frequency domain-slow time domain moving target echo signal after the FFT, denoted as the second echo signal.

[0174] Specifically, Represented as:

[0175]

[0176] Where f represents the distance frequency.

[0177] S3. Because the moving target crosses multiple beams, it generates additional azimuth window modulation, thus affecting the second echo signal. Complex range and azimuth migration and modulation window compensation are performed to obtain the third echo signal s1(f, t). m ).

[0178] Specifically, it includes the following steps:

[0179] S3.1 Constructing the generalized sliding window matching function H gm (f,t) m ;t inq , t inq+1 (b2, b3).

[0180] Specifically, the generalized sliding window matching function H gm The formula is as follows:

[0181]

[0182] in,

[0183] ΔT q+1，q =t inq+1 -t inq This represents the duration of time it takes for a moving target to pass through the q-th beam;

[0184] S3.2, Apply the generalized sliding window matching function H gm (f,t) m ;t inq , t inq+1 b2, b3) and the second echo signal Multiplying these together yields the third echo signal s1(f,t) after compensation for higher-order distance and azimuth migration. m ).

[0185] Specifically, the third echo signal s1(f,t) m The calculation formula for ) is as follows:

[0186]

[0187] in,

[0188] Indicates the start time of the q-th sliding window;

[0189] This indicates the duration of the window used by the q-th sliding window operation.

[0190] S4. Compensate the third echo signal s1(f,t) using Keystone transform. m The distance traveled by the signal was used to obtain the fourth echo signal s2(f, t). τ ), and the fourth echo signal s2(f,t) τ Perform an inverse Fast Fourier Transform along the range direction and an inverse Fast Fourier Transform along the azimuth direction to obtain the fifth echo signal s3(t, f). τ ).

[0191] Specifically, it includes the following steps:

[0192] S4.1 Substitute the Keystone transform expression into the third echo signal s1(f, t) m The fourth echo signal s2(f,t) is obtained from the signal. τ ).

[0193] The Keystone transformation expression is as follows:

[0194]

[0195] t τ Represents the slow-time variable after the Keystone transformation;

[0196] Then the echo signal of the fourth moving target s2(f,t) τ ) is represented as:

[0197]

[0198] S4.2, Regarding the fourth echo signal s2(f,t) τ The fifth echo signal is obtained by performing an inverse Fast Fourier Transform along the range direction and a Fast Fourier Transform along the azimuth direction.

[0199] Specifically, the fifth echo signal s3(t, f) τ ) is represented as:

[0200]

[0201] The azimuth Doppler frequency variable representing the signal of a moving target;

[0202] After the above operations, the distance traveled and migration of the moving target are better compensated, and the moving target in... and The peak value is formed at that point.

[0203] S5, Regarding the fifth echo signal By performing a peak retrieval operation, we can obtain:

[0204] Estimated initial beam time of moving target Estimated beam crossing time of moving targets Estimated value of radial acceleration of a moving target Estimated radial jerk of a moving target

[0205] And obtain the peak location estimate. Estimates of the azimuth Doppler frequency variable of the moving target signal Then, the estimated radial velocity of the moving target is obtained based on the peak coordinates. Estimated value of scene center slant distance

[0206] Specifically, it includes the following steps:

[0207] S5.1 Since the phase parameters of a moving target are usually unknown a priori, the estimated value of the initial beam time... Estimated beam crossing time of moving targets Estimated radial velocity of a moving target Estimated value of scene center slant distance Estimated value of radial acceleration of a moving target And the estimated value of the radial jerk of the moving target. This can be obtained through the following steps:

[0208]

[0209] in,

[0210] Peak indicates peak search operation;

[0211] KT represents the Keystone transformation operation;

[0212] IFT f This represents the inverse Fourier transform of the distance;

[0213] The matched value representing the radial acceleration of a moving target;

[0214] The matching value represents the radial jerk of the moving target;

[0215] S5.2, based on Obtain peak location estimate and estimated value This can be obtained through the following steps:

[0216]

[0217] This represents the estimated location of the peak distance;

[0218] This represents the estimated value of the azimuth Doppler frequency variable of the moving target signal.

[0219] S5.3, Using peak coordinates The estimated value of the scene center slope distance is calculated. and utilize Calculate the estimated radial velocity of the moving target.

[0220] Based on the above steps, we can obtain These are the eight estimates.

[0221] S6, based on Correcting the second echo signal The range and azimuth migration within the beam are measured, and the echo energy of moving targets dispersed in different beams (grating lobes) is accumulated to obtain the multi-beam focusing accumulation and radial range estimation results.

[0222] Specifically, it includes the following steps:

[0223] S6.1 Based on the estimated value obtained in step S5 The following multibeam focusing matching function can be constructed, and the multibeam focusing matching function is expressed as:

[0224]

[0225] S6.2 Matching the multibeam focusing function With the second echo signal Multiplying these components yields the sixth echo signal s4(f,t) after distance and azimuth migration compensation and modulation window adjustment. m ).

[0226] S6.3, Regarding the sixth echo signal s4(f,t) m Perform inverse Fast Fourier Transform (FFT) along the range direction and FFT along the azimuth direction to obtain the multibeam focusing accumulation and radial range estimation results.

[0227] Specifically, the results of multi-beam focusing accumulation and radial distance estimation. Represented as:

[0228]

[0229] Through processing steps S1 to S6, the range and Doppler migration of moving targets within different beams are effectively compensated. Simultaneously, the moving target signals from different beams are uniformly compensated to the same range and Doppler plane. Therefore, the energy of moving target signals from multiple beams is effectively combined and accumulated. Consequently, compared to single-beam focusing processing, the cumulative gain of the moving target signal is significantly increased, which is more beneficial for subsequent moving target inspection processing.

[0230] The invention will be further described below with reference to simulation experiments.

[0231] 1. Simulation conditions:

[0232] The simulation parameters of the radar system are the carrier frequency f. c =2GHz, distance bandwidth B r=100MHz, pulse repetition frequency (PRF) =1200Hz, radar platform altitude 799km, platform speed 7200m / s, 3 synthetic beams. In the experiment, the target parameters were set to v. r =130.0m / s, v a =260m / s, the equivalent radial motion parameters of the moving target are b1 = -130m / s and b2 = 17.2876m / s. 2 In the simulation, the signal-to-noise ratio of the pulse compression of the moving target echo was set to -7dB.

[0233] 2. Simulation Experiment Content and Result Analysis

[0234] Figures 3-12 The simulation results of multi-beam joint focusing processing are presented.

[0235] The result of pulse compression processing of the target echo signal is as follows Figure 3 As shown, due to the low signal-to-noise ratio, the target signal is submerged in noise.

[0236] In order to better observe the distribution characteristics of the target signal, Figure 4 The results of noise-removed target signal pulse compression are presented. Due to severe range migration, the target energy diffuses into multiple range cells, resulting in severe energy defocusing. Furthermore, since the target spans three beams, the target signal is distributed in three stages in the azimuth and time domains.

[0237] Figure 5 The Doppler spectrum distribution of the target is presented. Due to the influence of unknown relative motion, the target's energy is also severely defocused along the Doppler dimensions, and the target remains submerged in noise.

[0238] Figure 6 The results of the noise-free Doppler spectrum distribution are given, and it can be seen that the target energy is severely defocused in terms of distance and Doppler dimensions.

[0239] Figure 7 and 8 The matching results of the target initial time and processing window length are presented. The figure shows that the target signal forms a distinct spike. By detecting the peak position using peak retrieval, the target's initial time and cross-beam time can be estimated.

[0240] Figure 9 The target radial acceleration matching results are presented. As shown in the figure, when the searched acceleration matches the target's actual acceleration parameters, a significant peak appears in the output. The target's radial acceleration can be estimated based on this peak. Combining the radial acceleration estimate, a corresponding compensation function can be constructed to estimate the target's velocity parameters, such as... Figure 10 As shown.

[0241] Finally, based on the estimated target motion parameters, a multi-beam focusing matching function can be constructed to obtain the multi-beam joint focusing result, such as... Figure 11 and 12 As shown in the figure, the target achieved good focusing results in both the range and Doppler domains.

[0242] Table 1 presents the specific parameter estimation results, and it can be seen from the table that the proposed method has good parameter estimation performance.

[0243] Table 1

[0244]

[0245] Example 2:

[0246] A storage medium storing a computer program for multi-beam joint focusing of a time-sensitive moving target, wherein the computer program causes a computer to perform the following steps:

[0247] Transmit a linear frequency modulated signal and acquire the first echo signal reflected by the moving target;

[0248] The first echo signal is demodulated, pulse compressed, and subjected to a fast Fourier transform along the range direction in sequence to obtain the second echo signal;

[0249] The second echo signal is subjected to complex range and azimuth migration and modulation window compensation to obtain the third echo signal;

[0250] The fourth echo signal is obtained by compensating for the range migration of the third echo signal using Keystone transform; and the fifth echo signal is obtained by performing inverse fast Fourier transform along the range direction and fast Fourier transform along the azimuth direction on the fourth echo signal.

[0251] Peak retrieval is performed on the fifth echo signal to obtain the estimated values ​​of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target.

[0252] Based on the estimated values ​​of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target, the estimated values ​​of the peak distance position, the azimuth Doppler frequency variable of the moving target signal, the radial velocity of the moving target, and the slant distance of the scene center are obtained.

[0253] Based on the obtained estimates, the range and azimuth migration within the beam of the second echo signal are corrected, and the echo energy of moving targets dispersed in different beams is accumulated to obtain the multi-beam focusing accumulation and radial range estimation results.

[0254] Example 3:

[0255] An electronic device, comprising:

[0256] One or more processors;

[0257] Memory; and

[0258] One or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs including steps for performing the following:

[0259] Transmit a linear frequency modulated signal and acquire the first echo signal reflected by the moving target;

[0260] The first echo signal is demodulated, pulse compressed, and subjected to a fast Fourier transform along the range direction in sequence to obtain the second echo signal;

[0261] The second echo signal is subjected to complex range and azimuth migration and modulation window compensation to obtain the third echo signal;

[0262] The fourth echo signal is obtained by compensating for the range migration of the third echo signal using Keystone transform; and the fifth echo signal is obtained by performing inverse fast Fourier transform along the range direction and fast Fourier transform along the azimuth direction on the fourth echo signal.

[0263] Peak retrieval is performed on the fifth echo signal to obtain the estimated values ​​of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target.

[0264] Based on the estimated values ​​of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target, the estimated values ​​of the peak distance position, the azimuth Doppler frequency variable of the moving target signal, the radial velocity of the moving target, and the slant distance of the scene center are obtained.

[0265] Based on the obtained estimates, the range and azimuth migration within the beam of the second echo signal are corrected, and the echo energy of moving targets dispersed in different beams is accumulated to obtain the multi-beam focusing accumulation and radial range estimation results.

[0266] It is understood that the storage medium and electronic device provided in the embodiments of the present invention correspond to the above-described time-sensitive moving target multi-beam joint focusing method. The explanations, examples, and beneficial effects of the relevant content can be referred to the corresponding content in the time-sensitive moving target multi-beam joint focusing method, and will not be repeated here.

[0267] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0268] 1) This invention uses a new radar transmission system, namely, a space-based distributed detection platform with fully coherent transmission and reception to detect moving targets. Its purpose is to effectively improve the radar's ability to detect small / stealthy targets by increasing the observation time and using long-term coherent accumulation technology.

[0269] 2) Since the generalized sliding window matching function and multi-beam focusing matching function constructed in this invention are linear processing procedures, they overcome the problem that existing methods use nonlinear methods to compensate for the energy defocusing of moving targets, resulting in severe energy loss and making weak moving targets easily submerged in noise. This improves the performance of the space-based distributed detection platform with fully coherent transmission and reception for focusing on weak moving targets.

[0270] 3) Because the present invention compensates for the additional azimuth window modulation caused by the moving target crossing multiple beams and the complex range and azimuth migration within a single beam by searching for the initial beam time of the moving target, the target cross-beam time, the slant distance of the scene center, the radial velocity, the radial acceleration and the radial jerk, the moving target achieves precise focusing of weak moving targets.

[0271] 4) Since the present invention performs moving target parameter estimation after coherent cumulative focusing processing, it overcomes the problem that the parameter estimation performance of existing methods is severely affected by noise, resulting in a serious decline in parameter estimation performance under low SNR conditions, and improves the performance of ground weak moving target parameter estimation under low SNR conditions.

[0272] It should be noted that, through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the prior art, can be embodied in the form of software products. These computer software products can be stored in storage media, such as ROM / RAM, magnetic disks, optical disks, etc., and include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or certain portions of the embodiments. In this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further restrictions, an element defined by the phrase "comprising a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0273] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A time-sensitive moving target multi-beam joint focusing method, characterized in that, The method includes: Transmit a linear frequency modulated signal and acquire the first echo signal reflected by the moving target; The first echo signal is demodulated, pulse compressed, and subjected to a fast Fourier transform along the range direction in sequence to obtain the second echo signal; The second echo signal is subjected to complex range and azimuth migration and modulation window compensation to obtain the third echo signal; The fourth echo signal is obtained by compensating for the range migration of the third echo signal using Keystone transform; and the fifth echo signal is obtained by performing inverse fast Fourier transform along the range direction and fast Fourier transform along the azimuth direction on the fourth echo signal. Peak retrieval is performed on the fifth echo signal to obtain the estimated values ​​of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target. Based on the estimated values ​​of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target, the estimated values ​​of the peak distance position, the azimuth Doppler frequency variable of the moving target signal, the radial velocity of the moving target, and the slant distance of the scene center are obtained. Based on the obtained estimates, the range and azimuth migration within the beam of the second echo signal are corrected, and the echo energy of moving targets dispersed in different beams is accumulated to obtain the multi-beam focusing accumulation and radial range estimation results. The process of performing complex range and azimuth migration and modulation window compensation on the second echo signal to obtain the third echo signal includes: S3.1 Constructing the generalized sliding window matching function H gm (f,t m ;t inq ,t inq+1 b2, b3), and the generalized sliding window matching function H gm Represented as: Where f represents the distance frequency; t m Indicates location and time; t inq The value represents the moment when the moving target enters the q-th beam of the radar, where q = 1, 2, ..., N; N represents the number of beams; b2 represents the radial acceleration of the moving target; b3 represents the radial jerk of the moving target; rect represents the rectangular window function; j represents the imaginary unit symbol; c represents the speed of light; f c ΔT represents the carrier frequency of the linear frequency modulated signal transmitted by the radar. q+1,q =t inq+1 -t inq This represents the duration of time it takes for a moving target to pass through the q-th beam; S3.2, Apply the generalized sliding window matching function H gm (f,t m ;t inq ,t inq+1 b2, b3) and the second echo signal Multiplying these together yields the third echo signal s1(f,t) after compensation for higher-order distance and azimuth migration. m The third echo signal is represented as: Where B represents the bandwidth of the transmitted linear frequency modulated signal; This indicates the start time of the q-th sliding window; The duration of the window used by the q-th sliding window operation is represented; exp represents the exponent with the natural constant e as the base; R0 represents the slant distance from the scene center. The method corrects the range and azimuth migration within the beam of the second echo signal based on the obtained estimates, and simultaneously accumulates the echo energy of moving targets dispersed in different beams to obtain multi-beam focusing accumulation and radial range estimation results, including: S6.1 Construct a multibeam focusing matching function, and the multibeam focusing matching function is expressed as: in, This represents an estimate of the initial beam time of a moving target; This represents an estimate of the time it takes for a moving target to cross the beam. This represents an estimate of the radial acceleration of a moving target. This represents an estimate of the radial jerk of a moving target. S6.2 Matching the multibeam focusing function With the second echo signal Multiplying these components yields the sixth echo signal s4(f,t) after distance and azimuth migration compensation and modulation window compensation. m ); S6.3, Regarding the sixth echo signal s4(f,t) m Perform inverse Fast Fourier Transform (FFT) along the range direction and FFT along the azimuth direction to obtain the multibeam focusing accumulation and radial range estimation results.

2. The time-sensitive moving target multi-beam joint focusing method as described in claim 1, characterized in that, The transmitted linear frequency modulated signal is represented as: The first echo signal reflected by the moving target is represented as: Among them, s t (t) represents the transmitted linear frequency modulated signal; s r (t,t m This represents the first echo signal reflected by the moving target; rect represents a rectangular window function; t represents the distance in time; T P This represents the pulse width of the linear frequency modulated signal transmitted by the radar. exp represents an exponent with the natural constant e as its base; j represents the symbol for the imaginary unit; K r It is the modulation frequency of a linear frequency modulation signal; f c This indicates the carrier frequency of the linear frequency modulated signal transmitted by the radar. t m Indicates location and time. R s (t m )≈R0+b1t m +b2t m 2 +b3t m 3 Indicates instantaneous slant distance; R0 represents the slant distance from the scene center; b1 represents the radial velocity of the moving target; b2 represents the radial acceleration of the moving target; b3 represents the radial jerk of the moving target; t inq This indicates the moment when a moving target enters the q-th beam of the radar, where q = 1, 2, ..., N; and N represents the number of beams. c represents the speed of light.

3. The time-sensitive moving target multi-beam joint focusing method as described in claim 2, characterized in that, The process of demodulating the first echo signal, compressing the pulse, and performing a fast Fourier transform along the range direction to obtain the second echo signal includes: S2.1, Regarding the received first echo signal s r (t,t m The signal is demodulated to obtain the demodulated echo signal. S2.2, Demodulated echo signal Pulse compression processing is performed to obtain the pulse-compressed echo signal s. base (t,t m ); S2.3, The echo signal s after pulse compression base (t,t m Perform a Fast Fourier Transform (FFT) along the range direction to obtain the range-frequency domain-slow time domain moving target echo signal after the FFT, denoted as the second echo signal. And the second echo signal Represented as: in, f represents the distance frequency; B represents the bandwidth of the transmitted linear frequency modulated signal.

4. The time-sensitive moving target multi-beam joint focusing method as described in claim 3, characterized in that, The process of compensating for the range migration of the third echo signal using Keystone transform to obtain the fourth echo signal, and then performing an inverse Fast Fourier Transform (FSFT) along the range direction and an FFT along the azimuth direction to obtain the fifth echo signal, includes: S4.1 Substitute the Keystone transform expression into the third echo signal s1(f,t) m The fourth echo signal s2(f,t) is obtained from the signal. τ ), and the echo signal of the fourth moving target s2(f,t) τ ) is represented as: Among them, t τ Represents the slow-time variable after the Keystone transformation; S4.2, Regarding the fourth echo signal s2(f,t) τ The fifth echo signal is obtained by performing an inverse Fast Fourier Transform along the range direction and a Fast Fourier Transform along the azimuth direction. And the fifth echo signal Represented as; in, The azimuth Doppler frequency variable represents the signal of a moving target.

5. The time-sensitive moving target multi-beam joint focusing method as described in claim 4, characterized in that, The peak retrieval operation on the fifth echo signal to obtain estimates of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target includes: in, Peak indicates peak search operation; KT represents the Keystone transformation operation; IFT f This represents the inverse Fourier transform of the distance; This represents an estimate of the initial beam time of a moving target; This represents an estimate of the time it takes for a moving target to cross the beam. This represents an estimate of the radial acceleration of a moving target. This represents an estimate of the radial jerk of a moving target. Matching value representing the radial acceleration of a moving target The matching value represents the radial jerk of a moving target.

6. The time-sensitive moving target multi-beam joint focusing method as described in claim 5, characterized in that, The estimation of the initial beam time, the cross-beam time, the radial acceleration, and the radial jerk of the moving target, based on the initial beam time, the cross-beam time, the radial acceleration, and the jerk of the moving target, is used to obtain the estimated peak distance position, the estimated azimuth Doppler frequency variable of the moving target signal, the estimated radial velocity, and the estimated slant distance of the scene center, including: in, This represents the estimated location of the peak distance; The estimated value of the azimuth Doppler frequency variable representing the signal of a moving target; Based on and The estimated value of the scene center slope distance is calculated. and the estimated radial velocity of the moving target 7. A storage medium, characterized in that, It stores a computer program for time-sensitive moving target multi-beam co-focusing, wherein the computer program causes a computer to execute the time-sensitive moving target multi-beam co-focusing method as described in any one of claims 1-6.

8. An electronic device, characterized in that, include: One or more processors; Memory; as well as One or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs including methods for performing the time-sensitive moving target multibeam co-focusing method as described in any one of claims 1-6.

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