Features Extraction And Analysis Of Radar Target With Micro Doppler

Radar micro Doppler effects can be seen everywhere in the nature,and it is a distinctive characteristic of a target.Feature extraction and parameter estimation of micro Doppler can depict motion information of target exactly,which provides detail about the target identity.Thus,the micro Doppler signature has become a hotspot in radar target detection and recognition field.The thesis focus on micro Doppler components separation and characteristic extraction under different conditions,and the achievements are introduced as following:1.Research of micro Doppler effects is carried out.Two kind of micro motion simulation methods based on scattering point model and the electromagnetic calculation model are introduced and radar signal processing way of both narrow-band and wide-band conditions has been studied.The theoretical derivation of micro Doppler frequency expression and feature extraction method base on time-frequency transform technique are established.2.In narrow-band situations,a new method based on SFMT(Sinusoidal Frequency Modulation Transform)to extract micro motion characteristic is proposed.Micro Doppler signal of narrow-band usually has multiple components,but with sinusoidal FM.Thus,we combine micro Doppler feature parameter with SFMT theory to achieve parameter estimation of micro motion target.Compared with traditional method,the new method no longer relies on the time-frequency spectrum and achieve higher estimation precision.For the multiple components,the CLEAN technique is introduced to achieve separation and reconstruction of components and solve overlap between different scatters.3.A new method of unwrapping phase ambiguity is proposed.In wide-band situations,the radar echo signal achieves high range resolution,and this makes PDR(phase derived range)technique possible.The basic theory of phase ranging technique is discussed,and phase ambiguity problem is analyzed.On this basis,we introduce initial phase ambiguity and inner-pulse phase increment ambiguity,and propose the unwrapping method based on multi-level delayed and conjugated multiplication.This method works well even in the case of high micro Doppler ambiguity.