The Key Technology Study Of Coherent Doppler Wind Lidar

Accurate measurement of atmospheric wind field receives more and more attention in meteorology,military,aerospace and other fields.1550 nm fiber-based coherent pulsed Doppler lidar has become a hot research at home and abroad in terms of the advantage of eye-safety,small size,high accuracy of wind measurement,real time,high spatial and temporal resolution even in the clear atmosphere.And 1550 nm fiber-based coherent pulsed Doppler lidar has the advantages of the high mobility,good concealment because of its small size.The thesis is organized as follows:In chapter 1,applications of wind lidar in meteorology,military,aerospace and other fields are described in detail.Then the research process of the lidar at home and abroad is summarized,and the meaning of the subject is clear.In chapter 2,the principle of coherent Doppler wind lidar is analyzed.At first,the system composition is introduced.Based on the principle and system diagram of coherent Doppler wind lidar,the lidar equation is analyzed,and the key parameters of lidar equation including backscatter coefficient and atmospheric transmittance under the American standard atmospheric conditions are simulated.By introducing coherent detecting principle,the coherent signal expression is deduced,and then the concept of coherent lidar is given.A concept of backscatter propagated local oscillator(BPLO)is employed to simplify the CNR mathematical calculating at target plane.The key parameters of SNR: heterodyne efficiency and antenna efficiency,is deduced by analyzing the SNR expression.In chapter 3,the elements causing error to the coherent Doppler wind lidar is analyzed.The elements include the performance of laser,spectrum resolution,SNR.The system parameters and the detecting range are determined by analyzing system error.In chapter 4,the frequency extraction algorithm,scanning system,and telescope system is analyzed.The conclusion of zero-padding Fast Fourier Transform applying to the frequency extraction in the coherent wind lidar is made by analyzing the PP algorithm,improved PP algorithm and zero-padding Fast Fourier Transform.The parameters of scanner is analyzed by simulation.A telescope is designed through the conclusion of antenna efficiency.In chapter 5,the experimental and field test of the coherent wind lidar are carried out.The feasibility of the lidar is verified by the temporary make-up on the test bed,and the speed of the coherent Doppler wind lidar is calibrated by the speed motor.The wind profiling of the wind field is getting by field test.In chapter 6,the work has been summarized and the shortcomings of the work are pointed out.And then the future job is pointed out.