| In the process of detecting the target,the radar will inevitably be affected by the clutter reflected from the background around the target.These clutters mainly come from ground vegetation,buildings,clouds and rain,and birds.The presence of clutter makes radar detection of targets much more difficult,Clutter suppression technology is a very important technology in radar signal processing.It can retain the target signal to the maximum while suppressing clutter,thereby improving the radar's ability to detect the target.In many cases,the clutter intensity is even greater than the target intensity,so researching methods that can effectively suppress clutter has always been an important part of radar research.The difference in Doppler frequency caused by the different radial speeds of moving targets and clutter relative to the radar antenna is the main basis for the design of clutter suppression filters.This paper mainly studies the methods of radar clutter suppression on ground and airborne platforms.Firstly,First,analyze the distribution model and power spectrum of the ground clutter received by the ground-based radar,and use the ZMNL method to simulate the Rayleigh distribution and the Weibull distribution ground clutter models,and then analyze the ground clutter received by the radar under the airborne platform.The characteristics of space-time two-dimensional clutter were simulated and analyzed,which laid the foundation for the subsequent research on clutter suppression technology.Then it studies the moving target display technology(MTI)and moving target detection technology(MTD)commonly used by ground-based radars to suppress clutter,and briefly introduces the principle of MTI technology,the "blind speed" problem and the methods used to solve the "blind speed" problem,Studied several optimization design methods of MTI filters,and then designed optimized MTI filters by eigenvector method and zero distribution method,and analyzed their frequency response,and used the staggered pulse repetition frequency method to solve the "blind speed" Before designing the optimized ground clutter filter,genetic algorithm is used to optimize the staggered code,and then the weight coefficient of the optimized filter is calculated by the eigenvector method,and its frequency response curve is given.Next,I studied the MTD technology.First,the conventional MTD filter bank was realized by cascading the MTI and FFT to filter out the clutter at zero frequency,and the performance was analyzed.The level is relatively high,so the Doppler filter bank is designed with Gachebyshev window and Hamming window to reduce the sidelobe level and the influence of sidelobe clutter,and then the optimized MTD filter is designed through the FIR filter We designed the point Doppler filter bank and the equal interval Doppler filter respectively,and achieved zero Doppler frequency processing through Kalmas filter and clutter map technology,and finally used the designed AMTD filter The measured data is filtered,and the processing results are analyzed.Finally,the method of clutter suppression under the airborne platform is studied.First,the distribution characteristics of the clutter received by the phased array antennas of different installations on the space-time two-dimensional plane,namely the distance Doppler characteristics of the clutter and Angle Doppler characteristics,and then introduced the principle of airborne phased array radar space-time two-dimensional adaptive signal processing(STAP)and SATP's dimensionality reduction method,Focus on the study of the FA/EFA algorithm that first performs Doppler pre-filtering,and then performs adaptive signal processing on the output of one or more Doppler channels,and finally realized the dimensionality reduction space-time adaptive processing using the EFA method By comparing the results of the PD method on the clutter suppression,it is concluded that the EFA method has superior clutter performance. |
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