Application Research On Simulation Of Land Radar Surface Target Echo

In the process of soft landing on the surface of the celestial body,the distance and speed information provided by the phased array sensor is needed to ensure the safe landing of the lander on the surface of the celestial body.Therefore,we need to verify the radar system performance.Based on the application scenario of landing radar,this thesis proposes a simulation method of landing radar surface target echo based on Mars threedimensional terrain,and uses CPU-GPU platform to accelerate the generation of radar surface target echo data.Through the simulation test of digital platform,the effectiveness of radar system function and the stability of radar system are verified.First,determine the range and speed signal system of the landing radar.Based on the system,the radar equations are combined to analyze the influencing factors that affect the amplitude and phase of the surface target echo,and the distribution characteristics of the surface target echo amplitude are analyzed.Secondly,according to the real topographic characteristics of the star surface,we should establish the micro-undulation model,impact crater model and bump stone model in turn.At the same time,we also need to establish the statistical model of impact crater and stone surface distribution according to the relevant data.And then,on the basis of the original DEM data of the star surface,we should add the undulation model,impact crater model and stone model in order according to the statistical characteristics to generate the simulation terrain data.Then,considering that the radar scattering cross-sectional area will affect the echo amplitude of the surface target,we need to established the surface electromagnetic scattering model.Firstly,reading the radar trajectory data and extract the radar's movement attitude,height,speed,and beam information from the data,combine these information with the simulated terrain data to establish a coordinate system,and obtain the beam center irradiation point and beam irradiation range.After the beam irradiation range is determined,it is divided into bins.For the problem that the e equidistant-equal Doppler bands are only applicable to flat land,and in order to better apply to the GPU,we use the rectangular grid division method to divide the beam range.At the same time,using the down-view method to judge the obscuration effect of the scene.Then compare and improve different models to obtain the backscattering coefficient model which is closest to the actual situation.Combine the backscattering coefficient model,the shadowing effect and the echo amplitude distribution characteristics to establish an electromagnetic scattering model,and combine the phased array antenna pattern to design the echo simulation method of the surface target.Finally,aiming at the problem of too long time in the actual simulation process,the parallel algorithm design is combined with GPU Programming architecture.This thesis analyzes the two parallel levels in the simulation process of surface target echo in detail,designs the kernel function from memory management and thread allocation,and realizes the off-line fast simulation of surface target echo of 3D terrain under the GPU Programming Framework by the hybrid programming technology of MATLAB and CUDA C.Then design the software based on the whole process of surface target echo simulation,and use MATLAB's GUI and App Complier to complete the interface design and software packaging.Finally,use the distance and speed algorithm to solve the echo data generated off-line,and compared with the traditional echo simulation method based on CPU to verify its efficiency to verify the effectiveness of the results.