Low-altitude Small Target Radar Detection And Signal Processing Implementation Technology

Low-altitude small targets represented by unmanned aerial vehicles have developed rapidly in recent years,due to their low flying height,small radar cross-sectional area,and weak radar echo,radar detection capabilities have dropped sharply.In addition,as a kind of clean,low-cost and renewable energy,wind energy has developed rapidly.The number of wind farms is also increasing year by year.However,the wind farms would have a serious impact on the radar system,and reduce the ability of the radar to detect targets,especially affect the detection of low-altitude small targets.Therefore,studying how to detect low-altitude small targets under the background of wind farm clutter has a great significance to improve the radar's early warning and detection capabilities.Furthermore,FPGA is widely used in radar signal processing system which relies on computing speed and parallel processing ability and flexible programmable and timing control.Therefore,studying the FPGA engineering implementation of part radar signal processing systems has high engineering application value.Firstly,this thesis introduces the basic algorithms of radar signal processing system,simulates and discusses them through MATLAB,including A/D sampling,digital down converter,pulse compression,beam forming,moving target detection,etc.Secondly,the radar model of windmill based on the scattering points superposition theory is established,and analyzes the characteristics of windmill radar echo in the time and frequency domain.Windmill radar echo has periodic peaks in the time domain.And windmill radar echo has the characteristic of Doppler spectrum broadening in the frequency domain.Then,the frequency domain characteristics of the windmill radar echo are analyzed in two cases:the windmill blade and the radar beam are vertical,and the windmill blade and the radar beam are not vertical.At the same time,the height of the windmills in the wind farm is fixed(elevation angle is fixed),the height of the low-altitude small target is uncertain(elevation angle is uncertain).A low-altitude small target detection method under the background of wind farm clutter is proposed according to the Doppler and elevation characteristics of windmills and low-altitude small targets,and the feasibility of the method is verified by simulation.Finally,combined with a scientific research project,the FPGA engineering implementation of part of the signal processing system of a low-altitude small target detection radar is introduced in detail.The programming of FPGA is mainly divided into three parts: the first is the FPGA implementation of part of the signal processing modules,the second is the timing control module of the radar signal processing system,the third is the interface communication module of the radar signal processing system.