Real-time simulation method for clutter signals with irregular contours

Abstract

The present invention discloses a real-time simulation method for clutter signals with irregular contours, which primarily addresses the problems of regularized spatial contours of clutter signals in the prior art, poor simulation fidelity, and lack of real-time performance. The method comprises the following steps: 1) recording shape information based on the actual clutter shape displayed on the P display; 2) setting the clutter simulation region and radar parameters; 3) calculating the actual range of clutter under the current beam and the number of clutter resolution units; 4) calculating the scattering cross-sectional area of ​​the clutter resolution unit and the echo power of the first clutter resolution unit; 5) calculating a sequence of clutter spatial correlation coefficients and modulating the echo power of each clutter resolution unit; 6) generating multiple sets of clutter amplitude and phase modulation coefficients, modulating the echo amplitude and phase of each clutter resolution unit in the slow time dimension, and generating clutter simulation data for a single CPI; and 7) repeating steps 3) to 6) as the beam rotates to complete the simulation of the clutter region signal. The present invention improves the fidelity and real-time performance of clutter signal simulation and can be used for target detection.

Description

Technical Field

[0001] The invention belongs to the technical field of signal processing, in particular to a real-time simulation method for clutter signals, which can be used for ground-based radar target detection. Background Art

[0002] Traditional radar signal simulation is mainly divided into function-level simulation and signal-level simulation. Function-level signal simulation does not involve the detailed process of signal generation and signal processing. It only judges the detection function of the radar algorithm to the target under certain criteria. This simulation method has great limitations and is not suitable for system-level simulation. Signal-level simulation starts from the mechanism of signal generation and fully describes the amplitude and phase changes of the signal. The radar effect display is the result of objective operation of set parameters. This simulation method can more accurately describe the clutter using mathematical statistical models. In modern radar system simulation, most clutter simulation methods use signal-level simulation methods.

[0003] A clutter signal simulation method proposed in the document "Modeling and Simulation of Complex Electromagnetic Environments for Radar" published in the China National Knowledge Infrastructure (CNKI) database divides ground and sea clutter into scattering units as surface clutter and calculates the area of ​​each scattering unit. The radar equation then calculates the echo power of each scattering unit. The echoes from each scattering unit are then superimposed to produce the final clutter simulation signal. However, due to the fixed parameters of this method, the spatial profile of the clutter is overly regularized, reducing the reliability of the clutter simulation.

[0004] To address the problem of regularizing clutter profiles, a representative approach is clutter simulation based on digital elevation maps. The paper "A Method for Suppressing Short-Range Heterogeneous Clutter in Airborne Radar Based on Elevation Maps," published in the CNKI database, proposes a general radar clutter model simulation method based on elevation maps. This method can account for the non-uniformity and heterogeneity of clutter signals. First, a digital elevation map is created based on terrain correlation function information. Next, the clutter terrain masking effect is determined based on geometric relationships using radar incident angle and terrain height information. The scattering area at different distances is calculated, and the scattering cross-sectional area of ​​the masked portion is set to zero. Finally, clutter signals are generated and superimposed based on the unit information recorded in the scattering cross-sectional area matrix. However, this simulation method requires extensive terrain data preprocessing, making it unsuitable for radar systems with real-time requirements. Therefore, ensuring both the fidelity of radar clutter signal simulation and the real-time performance of clutter signal simulation has become a pressing issue. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned existing technologies and propose a real-time simulation method for clutter signals with irregular contours, so as to avoid the preprocessing of terrain data and parameter solidification, and improve the authenticity and real-time performance of clutter signals in system simulation.

[0006] To achieve the above object, the technical solution of the present invention includes the following steps:

[0007] (1) Taking the ground-based radar as the simulation object, establish a height h and an azimuth beam width θ a , the incident angle of the beam irradiating the clutter area is θ, and the center of the radar is the reference center;

[0008] (2) Record the minimum radial distance R1 of the clutter in a real clutter area at the P display end of the radar, the distance interval ΔR of the clutter area, the upper half of the clutter area contour data, and the lower half of the clutter area contour data, wherein two different arrays 1 and array 2 with a length of len are used to record the upper half of the contour data and the lower half of the contour data respectively;

[0009] (3) Set the clutter area azimuth starting angle θ in the simulation system s 、Azimuth end angle θ e , clutter starting distance R s , clutter termination distance R e and the distance interval ΔR1 of the clutter area;

[0010] (4) When the radar beam scans the clutter area, the angle θ covering the clutter area is calculated based on the current beam orientation. c ;

[0011] (5) Calculate the proportion p of the clutter area covered by the current beam to the total clutter area based on the parameter information set in step (3), and calculate the array subscript index by the angle proportion p and the array length len in the clutter parameter information recorded in step (2):

[0012] p=θ c / (θ e -θ s ), index = p * len;

[0013] (6) Obtain the clutter distance y1 recorded in array 1 and the clutter distance y2 recorded in array 2 in step (2) by using the subscript index, and infer the actual clutter starting distance R under the current beam by the following formula: vs and the actual action end distance R ve These two real variable parameters:

[0014]

[0015] (7) Calculate the length l of a single clutter resolution unit for conventional radar and the length l2 of a single clutter resolution unit for pulse compression radar respectively;

[0016] (8) Calculate the rectangular clutter scattering unit area ΔA based on the radar beam information of step (1), the clutter position information set in step (3), and the clutter resolution unit length information of step (7), and calculate the clutter scattering cross-sectional area σ based on the area ΔA c ;

[0017] (9) According to the clutter range R in step (6) vs -R ve and the clutter resolution unit length in step (7), determine the number n of clutter resolution units under the current azimuth beam, and calculate its spatial correlation attenuation coefficient Γ(d);

[0018] (10) Using the zero-memory nonlinear variation method, generate n groups of clutter amplitude-phase modulation sequences that satisfy the power spectrum and obey the amplitude distribution, where the length of the sequence is the number of pulses m within the coherent processing period;

[0019] (11) Using the modulation sequences of step (9) and step (10), the clutter resolution unit echo signal is modulated in the fast time dimension and the slow time dimension respectively:

[0020] (11a) During the radar coherent processing cycle, the echo power P of the first clutter resolution unit is calculated based on the clutter scattering cross-sectional area in step (8). c Based on the echo signal of the first clutter resolution unit, the echo power of n adjacent clutter resolution units is modulated in the fast time dimension according to the spatial correlation attenuation coefficient of step (9):

[0021] (11b) performing amplitude and phase modulation on the echo signals of the n clutter resolution units in the slow time dimension according to the n groups of coefficients in step (10), and performing vector superposition on the modulated echo signals of each clutter scattering point to generate clutter simulation matrix data within a single coherent processing cycle of the radar;

[0022] (12) As the antenna beam rotates, steps (4) to (11) are repeated to complete the signal simulation in the clutter region of the radar system.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The present invention divides the clutter range under the current beam pointing direction into multiple adjacent clutter resolution units by calculating the clutter resolution unit length information. The clutter signals of the adjacent clutter resolution units are modulated on the fast time dimension using the spatial correlation coefficient to modulate the clutter power, and on the slow time dimension using the amplitude and phase modulation coefficient to modulate the clutter amplitude and phase information. This can reflect the characteristics of the clutter signal and make the clutter simulated within a single radar coherent processing cycle more realistic.

[0025] 2. The present invention utilizes recorded clutter shape parameter information during radar beam rotation to perform real-time transformations on the clutter start and end distance parameters during multiple radar coherent processing cycles. This not only makes the clutter signal appear irregular in its spatial profile on the radar's P-display terminal, making the simulation more realistic, but also minimizes time consumption, improving clutter signal simulation efficiency and meeting the system's real-time simulation requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is an implementation flow chart of the present invention;

[0027] Figure 2 Schematic diagram of the division of the radar low-incident-angle clutter rectangular resolution unit in the present invention;

[0028] Figure 3 Schematic diagram of generating a clutter data matrix in units of CPI in the present invention;

[0029] Figure 4 This is a time domain diagram of the clutter signal simulation of a single pulse in a CPI;

[0030] Figure 5 This is the simulation result diagram of MTD processing of clutter signals with different pulse numbers within one CPI;

[0031] Figure 6 This is a simulation result diagram of MTD processing of clutter signals with different clutter Doppler center velocities within a CPI;

[0032] Figure 7 It is a clutter airspace contour effect diagram simulated by existing technical methods;

[0033] Figure 8 This is a clutter airspace contour effect diagram simulated by the method of the present invention. DETAILED DESCRIPTION

[0034] The implementation and effects of the present invention are further described in detail below with reference to the accompanying drawings.

[0035] Reference Figure 1 , the implementation steps of the present invention are as follows:

[0036] Step 1: Record the clutter shape parameter information according to the actual clutter shape displayed by P.

[0037] Construct two arrays 1 and 2 with the same length len but different data contents. That is, array 1 is the near-end distance data of the clutter profile, and array 2 is the far-end distance data of the clutter profile. The data with the same subscript in array 1 and array 2 represent the nearest and farthest distance ranges of the clutter in one direction.

[0038] Divide the clutter area into len areas in azimuth. Use the first position of array 1 to save the distance data of the closest end of the first clutter area. Use the first position of array 2 to save the distance data of the farthest end of the first clutter area.

[0039] The nearest distance data and the farthest distance data of the divided areas are saved in the corresponding positions of array 1 and array 2 respectively in the order of azimuth from small to large, and the minimum radial distance R1 of the clutter area and the distance interval ΔR of the clutter area are recorded to complete the recording of the clutter shape parameter information.

[0040] Step 2: Set the clutter simulation area and radar operating parameters.

[0041] 2.1) Set the clutter area azimuth starting angle to θ in the simulation system s , the azimuth end angle is θ e , the clutter starting distance is R s , the clutter termination distance is R e The incident angle of the beam irradiating the clutter area is θ, and the distance interval ΔR1 of the clutter area is: ΔR1=R e -R s ;

[0042] 2.2) In the simulation system, a ground-based radar with a height of h is established and an azimuth beam width of θ is used. a The antenna has a beam direction indicated as θ0, and the radar transmits a signal with a pulse width of T p , linear frequency modulation signal with bandwidth B.

[0043] Step 3: Determine the actual range of clutter under the current beam.

[0044] This step is to start the actual action distance R of the clutter as the antenna rotates during the period when the radar beam illuminates the clutter simulation area. vs Distance to actual end of action R ve The parameters are transformed in real time to obtain the actual range of the clutter under the current beam. The specific implementation is as follows:

[0045] 3.1) According to the clutter azimuth starting angle θ s And the current radar beam azimuth center points to θ0, calculate the angle θ of the clutter area covered by the current beam c :θ c =θ0-θ s ;

[0046] 3.2) According to the clutter starting angle θ s , clutter termination angle θ e and the angle θ covering the clutter area c, calculate the proportion p of the clutter area covered by the current beam to the total clutter area: p = θ c / (θ e -θ s );

[0047] 3.3) Based on the proportion p of the clutter area covered by the beam to the total clutter area and the length len of the array of clutter shape parameters recorded in step 1, calculate the subscript index of the current beam pointing: index = p * len;

[0048] 3.4) Determine the clutter distance y1 recorded in array 1 and the clutter distance y2 recorded in array 2 by using the subscript index, that is, obtain the clutter profile data by searching the array by the subscript;

[0049] 3.5) According to the proportional indentation relationship between the recorded clutter shape parameter information and the set clutter simulation area parameter information in the azimuth and distance upward directions, calculate the actual clutter starting distance R under the current beam. vs and the actual action end distance R ve The values ​​of the two real variable parameters, that is, solving the following formula, we can get the starting distance R vs and the end distance R ve :

[0050]

[0051]

[0052] Step 4: Calculate the number n of clutter resolution units under the current azimuth beam and the scattering cross-sectional area σ of the clutter resolution unit under the current beam. c and the echo power P of the first clutter resolution unit c .

[0053] Reference Figure 2 , this step is specifically implemented as follows:

[0054] 4.1) According to the pulse width T of the radar transmission signal p , calculate the length l of the conventional radar clutter resolution unit without pulse compression processing:

[0055] l=(c·T p ) / 2·secθ, where c is the propagation speed of electromagnetic waves;

[0056] 4.2) Based on the bandwidth B of the radar transmit signal, calculate the clutter resolution unit length l2 of the pulse compression radar:

[0057] l2=c / (2B)·secθ;

[0058] 4.3) The actual starting distance R of the clutter obtained in step 3 vs, Actual action end distance R ve Parameters, and the length l of the conventional radar clutter resolution unit, calculate the number n of clutter resolution units under the current beam:

[0059] n=(R ve -R vs ) / l;

[0060] 4.4) Based on the oblique distance R between the radar and the clutter area, the azimuth beamwidth θ a and the length l of the conventional radar clutter resolution unit, calculate the area ΔA of the rectangular clutter scattering unit:

[0061] ΔA=R·θ a l;

[0062] 4.5) Based on the rectangular clutter scattering unit area ΔA and the backscattering coefficient σ of the current clutter area 0 , calculate the scattering cross-sectional area σ of the clutter resolution unit under the current beam c :

[0063] σ c =σ 0 ΔA;

[0064] 4.6) According to the scattering cross-sectional area σ of the clutter resolution unit under the current beam c , calculate the echo power P of the first clutter resolution unit c :

[0065]

[0066] Among them, P t is the radar transmission power, is the gain of the antenna to the clutter area, λ is the radar signal wavelength, R is the oblique distance between the clutter resolution unit and the radar, and L is the radar system loss.

[0067] Step 5: Calculate the clutter spatial correlation coefficient sequence Γ(d) and modulate the echo power of each clutter resolution unit.

[0068] 5.1) Set the arithmetic progression d of clutter resolution units to 0, 1, ..., n-1, where n is the total number of clutter resolution units in the current beam. Calculate the spatial correlation coefficient sequence Γ(d):

[0069] Γ(d)=aexp(-d 2 / b 2 )+(1-a)exp(-d / c)

[0070] Where a represents the proportion of the fluctuation component in the total energy, b and c are the decorrelation distances of the fast and slow fluctuation components, respectively;

[0071] 5.2) Using the spatial correlation coefficient sequence Γ(d) to analyze the echo power P of the first clutter resolution unit c Modulation is performed, and the formula is expressed as follows:

[0072] (P1,P2,...,P j ,...,P n )=P c *Γ(d)

[0073] Among them, P i is the echo power of the jth clutter resolution unit, j = 1, 2, ..., n.

[0074] Step 6: Generate n groups of noise amplitude and phase modulation sequences.

[0075] Using the zero-memory nonlinear transformation method, the independent Gaussian random sequence is filtered through a linear filter to generate a Gaussian correlation sequence that meets the power spectrum characteristics. The filtered sequence is then transformed through a nonlinear transformation relationship to make the sequence meet the amplitude distribution. The specific implementation is as follows:

[0076] 6.1) According to the clutter power spectrum width σ c , clutter center Doppler frequency f d , calculate the coefficient S(f) that satisfies the Gaussian power spectrum filter characteristics:

[0077]

[0078] Where S0 is an arbitrary constant, f represents the frequency of the clutter power spectrum, and the establishment of this frequency coordinate axis is related to the radar pulse repetition frequency;

[0079] 6.2) Generate two independent and uncorrelated Gaussian random sequences of length m, and filter each sequence using the coefficients S(f) of a Gaussian power spectrum filter, where m is the number of pulses in one coherent processing cycle;

[0080] 6.3) Using the two filtered sequences as the real and imaginary parts of the complex sequence, a set of clutter amplitude and phase modulation sequences with Gaussian power spectrum and Rayleigh-distributed modulus values ​​is obtained.

[0081] 6.4) Repeat (6.2) and (6.3) n times to obtain n groups of noise amplitude and phase modulation sequences.

[0082] Step 7: Generate clutter signal simulation data m(t) within a radar coherent processing cycle.

[0083] Reference Figure 3 , this step is specifically implemented as follows:

[0084] 7.1) According to the power modulation sequence P1, P2, ..., P j ,...,Pn , calculate the echo amplitude of n clutter resolution units:

[0085]

[0086] Among them, A j is the echo amplitude of the jth clutter resolution unit, j = 1, 2, ..., n;

[0087] 7.2) Based on n groups of clutter amplitude and phase modulation sequences, the echo data of n clutter resolution units are modulated in the slow time dimension and vector superposition is performed to obtain the clutter signal simulation data m(t) within a radar coherent processing cycle:

[0088]

[0089] Among them, c j (t) is the echo signal of the jth clutter resolution unit in a coherent processing cycle, A j is the echo amplitude of the jth clutter resolution unit, k ji is the amplitude and phase adjustment factor of the i-th pulse of the j-th clutter resolution unit, τ j is the time delay of the jth clutter resolution unit, PRT is the radar pulse repetition period, S j (·) is the radar transmission waveform signal of the jth clutter resolution unit, i = 1, 2, ..., m, m is the number of pulses in the coherent processing period, j = 1, 2, ..., n, n is the number of clutter resolution units.

[0090] Step 8: Repeat steps 3 to 7 as the antenna beam rotates to complete the signal simulation in the clutter area of ​​the radar system.

[0091] The beneficial effects of the present invention are further illustrated below with reference to specific simulation test results.

[0092] 1. Simulation conditions

[0093] Set the simulation parameters as shown in Table 1:

[0094] Table 1 Simulation parameters

[0095] parameter Parameter value Radar pulse repetition period 1ms Main beam azimuth effective width 10° radar signals Linear frequency modulation signal Radar signal pulse width 100us Radar signal bandwidth 2MHz System sampling rate 5MHz Radar carrier frequency 1.3GHz Clutter power spectrum Gaussian spectrum Clutter power spectrum width 0.32Hz Clutter speed 0m / s Clutter amplitude distribution Rayleigh distribution Clutter amplitude 1 Radar signal main processing flow Pulse compression, moving target detection

[0096] 2. Simulation Content

[0097] Simulation 1: Using the parameters in Table 1, under the conditions of the clutter starting range of 36km and the ending range of 38.5km, the clutter signal of a single pulse in a coherent processing cycle is simulated. The results are as follows: Figure 4 ,in, Figure 4 (a) is the time domain diagram of the clutter signal, and 4(b) is the time domain diagram of the clutter after pulse compression processing.

[0098] Figure 4 (a) and Figure 4 The simulation results of (b) show that the amplitude of the clutter simulation signal will increase due to the influence of the pulse compression algorithm, which will affect the radar target detection.

[0099] Simulation 2: Using the parameters in Table 1, under the conditions of clutter starting range of 6km and ending range of 8.5km, the clutter signal after pulse compression and moving target detection MTD algorithm is simulated. The results are as follows: Figure 5 ,in, Figure 5 (a) is the MTD result diagram of the clutter signal with 32 pulses as a coherent processing cycle. Figure 5 (b) is the MTD result diagram of the clutter signal with 8 pulses as a coherent processing cycle.

[0100] from Figure 5 (a) and Figure 5 The simulation results of (b) show that after the clutter signal passes through the moving target detection algorithm, the change in the number of pulses in the coherent processing cycle will affect the clutter power spectrum width, thereby affecting target detection.

[0101] Simulation 3: Using the parameters in Table 1, with the clutter starting range of 6km, the ending range of 8.5km and a fixed coherent processing cycle of 16 pulses, the clutter signal after pulse compression and moving target detection MTD algorithm is simulated. The results are as follows: Figure 6 ,in, Figure 6 (a) is the MTD result diagram of the clutter signal when the Doppler velocity at the center of the clutter is set to -10m / s, and 6(b) is the MTD result diagram of the clutter signal when the Doppler velocity at the center of the clutter is 8m / s.

[0102] from Figure 6 (a) and Figure 6 The simulation results of (b) show that the power spectrum of the moving clutter with Doppler frequency shift is offset from zero frequency, which will affect the detection of moving targets with a speed close to its own.

[0103] Simulation 4: Using the parameters in Table 1, the azimuth coverage ranges of the three clutter areas are set to 15°~50°, 60°~90°, and 70°~110°, respectively. The corresponding distance coverage ranges are 40km~60km, 50km~75km, and 100km~130km, respectively. The existing method of fixing parameters is used to simulate the clutter airspace contour effect, as shown in the following example. Figure 7 shown.

[0104] Figure 7 The results show that the existing clutter signal simulation method with fixed parameters will cause the regularization of the clutter spatial profile characteristics, greatly reducing the credibility of the clutter signal simulation.

[0105] In simulation 5, using the parameters in Table 1, the azimuth coverage ranges of the four clutter areas are set to 25° to 50°, 35° to 55°, 35° to 55°, and 85° to 120°, respectively. The corresponding distance coverage ranges are 10km to 15km, 50km to 75km, 20km to 90km, and 70km to 100km, respectively. The clutter airspace contour effect is simulated using the method of the present invention. Figure 8 As shown, Figure 8 (a) is a certain irregular clutter contour diagram recorded in step 1 of the method of the present invention, Figure 8 (b) is a diagram showing the spatial contour of clutter at the P display end simulated by the method of the present invention.

[0106] Figure 8 The results of (b) show that the clutter signal simulation method of the present invention not only makes the clutter spatial profile fit better, but also Figure 8 (a) The irregular shape of real clutter greatly improves the clutter spatial profile characteristics, making the clutter simulation more realistic.

Claims

1. A real-time simulation method for irregular contour clutter signals, characterized in that: The steps include: (1) Taking the ground-based radar as the simulation object, establish a height h and an azimuth beam width θ a , the incident angle of the beam irradiating the clutter area is θ, and the center of the radar is the reference center; (2) Record the minimum radial distance R1 of the clutter in a real clutter area at the P display end of the radar, the distance interval △R of the clutter area, the upper half of the clutter area contour data, and the lower half of the clutter area contour data, wherein two different arrays 1 and array 2 with a length of len are used to record the upper half of the contour data and the lower half of the contour data respectively; (3) Set the clutter area azimuth starting angle θ in the simulation system s 、Azimuth end angle θ e , clutter starting distance R s , clutter termination distance R e and the distance interval △R1 of the clutter area; (4) When the radar beam scans the clutter area, the angle θ covering the clutter area is calculated based on the current beam orientation. c ; (5) Calculate the proportion p of the clutter area covered by the current beam to the total clutter area based on the parameter information set in step (3), and calculate the array subscript index by the angle proportion p and the array length len in the clutter parameter information recorded in step (2): p=θ c / (θ e -θ s ),index=p*line; (6) Obtain the clutter distance y1 recorded in array 1 and the clutter distance y2 recorded in array 2 in step (2) by using the subscript index, and infer the actual clutter starting distance R under the current beam by the following formula: vs and the actual action end distance R ve These two real variable parameters: (7) Calculate the length l of a single clutter resolution unit for conventional radar and the length l2 of a single clutter resolution unit for pulse compression radar respectively; (8) Calculate the rectangular clutter scattering unit area ΔA based on the radar beam information of step (1), the clutter position information set in step (3), and the clutter resolution unit length information of step (7), and calculate the clutter scattering cross-sectional area σ based on the area ΔA c ; (9) According to the clutter range R in step (6) vs -R ve and the clutter resolution unit length in step (7), determine the number n of clutter resolution units under the current azimuth beam, and calculate its spatial correlation attenuation coefficient Γ(d); (10) Using the zero-memory nonlinear variation method, generate n groups of clutter amplitude-phase modulation sequences that satisfy the power spectrum and obey the amplitude distribution, where the length of the sequence is the number of pulses m within the coherent processing period; (11) Using the modulation sequences of step (9) and step (10), the clutter resolution unit echo signal is modulated in the fast time dimension and the slow time dimension respectively: (11a) During the radar coherent processing cycle, the echo power P of the first clutter resolution unit is calculated based on the clutter scattering cross-sectional area in step (8). c Based on the echo signal of the first clutter resolution unit, the echo power of n adjacent clutter resolution units is modulated in the fast time dimension according to the spatial correlation attenuation coefficient of step (9): (11b) performing amplitude and phase modulation on the echo signals of the n clutter resolution units in the slow time dimension according to the n groups of coefficients in step (10), and performing vector superposition on the modulated echo signals of each clutter scattering point to generate clutter simulation matrix data within a single coherent processing cycle of the radar; (12) As the antenna beam rotates, steps (4) to (11) are repeated to complete the signal simulation in the clutter region of the radar system.

2. The method according to claim 1, characterized in that In step (2), the two different arrays 1 and 2 have the same length len but different data contents, i.e., array 1 is the clutter near-end distance data, and array 2 is the clutter far-end distance data. The data with the same subscript in array 1 and array 2 represent the nearest and farthest distance ranges of the clutter in one direction.

3. The method according to claim 1, wherein: The distance interval △R1 of the clutter area set in step (3) is based on the set clutter termination distance R e and clutter starting distance R s Calculation: △R1=R e -R s ; The angle θ of the clutter area covered in step (4) c , is based on the current radar beam azimuth center pointing to θ0 and the set clutter azimuth starting angle θ s Calculation: θ c =θ0-θ s .

4. The method according to claim 1, wherein In step (7), the length l of a single clutter resolution unit of a conventional radar and the length l2 of a single clutter resolution unit of a pulse compression radar are calculated as follows: l=(c·T p ) / 2·secθ l2=c / (2B)·secθ Where c is the propagation speed of electromagnetic waves, T p is the pulse width of the radar transmit signal, B is the bandwidth of the radar transmit signal, and θ is the incident angle of the beam irradiating the clutter area.

5. The method according to claim 1, characterized in that The rectangular clutter scattering unit area △A and the clutter scattering cross-sectional area σ in step (8) c , are calculated as follows: △A=R·θ a ·l s c =s 0 ·△A Where R is the oblique distance from the radar to the clutter area, θ a is the radar azimuth beamwidth, σ 0 is the backscatter coefficient of the current clutter area.

6. The method according to claim 1, characterized in that In step (9), the spatial correlation attenuation coefficient Γ(d) of multiple clutter resolution units is calculated as follows: Γ(d)=aexp(-d 2 / b 2 )+(1-a)exp(-d / c) Where d is the arithmetic progression of the clutter resolution unit, a represents the proportion of the fluctuation component in the total energy, b and c are the decorrelation distances of the fast and slow fluctuation components, respectively.

7. The method according to claim 1, characterized in that In step (10), the zero-memory nonlinear variation method is used to generate n groups of clutter amplitude-phase modulation sequences that satisfy the power spectrum and obey the amplitude distribution, which is implemented as follows: (10a) According to the clutter power spectrum width σ c , clutter center Doppler frequency f d , calculate the coefficient S(f) that satisfies the Gaussian power spectrum filter characteristics: Where S0 is an arbitrary constant, f represents the frequency of the clutter power spectrum, and the establishment of its frequency coordinate axis is related to the radar pulse repetition frequency; (10b) Generate two sets of independent and uncorrelated Gaussian random sequences of length m, filter them using the filter coefficients of (10a), and use the filtered sequences as the real and imaginary parts of the complex sequence, respectively, to obtain a noise amplitude and phase modulation sequence that satisfies the Gaussian power spectrum and whose modulus value obeys the Rayleigh distribution.

8. The method according to claim 1, characterized in that The echo power P of the first clutter resolution unit in step (11a) c And the calculation is as follows: Among them, P t is the radar transmission power, is the gain of the antenna to the clutter area, λ is the wavelength of the radar signal, σ c is the clutter scattering cross-sectional area, R is the distance between the clutter resolution unit and the radar, and L is the radar system loss.

9. The method according to claim 1, characterized in that In step (11a), the echo power of n adjacent clutter resolution units is modulated by using the spatial correlation attenuation coefficient Γ(d) sequence to modulate the echo power P of the first clutter resolution unit. c Modulation is performed, and the formula is expressed as follows: (P1,P2,...,P j ,...,P n )=P c *Γ(d) Among them, P i is the echo power of the jth clutter resolution unit, j = 1, 2, ..., n, and n is the total number of clutter resolution units.

10. The method according to claim 1, characterized in that The signal c after amplitude and phase modulation in step (11b) j (t) and the vector superposition signal m(t) are expressed as follows: Among them, c j (t) is the echo signal of the jth clutter resolution unit in a coherent processing cycle, P j is the modulation power of the jth clutter resolution unit, k ji is the amplitude and phase adjustment factor of the i-th pulse of the j-th clutter resolution unit, τ j is the time delay of the jth clutter resolution unit, PRT is the radar pulse repetition period, S j (·) is the radar transmission waveform signal of the jth clutter resolution unit, i = 1, 2, ..., m, m is the number of pulses in the coherent processing period, j = 1, 2, ..., n, n is the number of clutter resolution units.

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