Modeling And Simulation Of Phase Coded Interrupted Continuous Coherent Wind Lidar

At present,1.55μm optical fiber laser radar system at home and abroad, generallyuses the zoom telescope system, that is to say, use the characteristics of Gauss beam, bycontrolling far field Gauss beam waist in order to suppress two echo and high echo andresolve the problem of distance ambiguity.but, the type of system detects is so near,theproblem of distance ambiguity is serious and the local oscillator always leakages thatlimits its application.At the same time,pulse coherent wind laser radar is experiencingsome kind of technical bottlenecks which researchers can not solve in shorttime.Meanwhile,the demand of wind laser radars which are much compact and are in lowcost is very urgent in our country.So,this thesis put forward a new concept which is calledphase coded cw coherent wind lidar.In order to research the feasibility of this kind oflaser wind radar,the numerical simulation method is used to the so called phase coded cwcoherent wind lidar system by modeling and simulation.Binary phase coding technique in this thesis and phase encoding technique inmicrowaves are in remarkable difference.The phase in this thesis is marked by distancegate whose length is determined by the length of the code,and the number of the distancegate is determined by the repeated cycle, then the serious problem of range in continuouswave laser wind radar is solved.As the symbol of the pseudo random sequences is solong that the velocity ambiguity is also solved,which is also the innovation and advantageof this kind of laser wind radar.Firstly,the structure of1.55μm phase coded interrupted cw coherent wind radar isdevised.At the same time,the principle of the1.55μm phase coded interrupted cwcoherent wind lidar is introduced,then the derivation and analysis of the ambiguityfunction of phase coded interrupted cw signal is showed,and the relationship of theambiguity function and resolution is discussed.Secondly, spectral function of phase coded interrupted continuous wave is analyzedon the basis of the principle of phase coding. The time-domain waveform,frequencyspectrum,ambiguity function and autocorrelation function of phase encoding cw lasersignal which is modulated by some common pseudo random sequences are showed inMATLAB software.and different kinds of pseudo random sequences is analyzed andcomparison.Finally,the laser echo signal of phase coded interrupted cw coherent wind lidar issimulated in MATLAB software.The optical mixing approach,quadrature demodulation and serial correlation approach are used to the echo of laser signal of wind lidar.Thefeasibility of phase coded interrupted cw coherent wind lidar is proved.