Research On Doppler Frequency Shift Estimation Technology Of Coherent Wind Lidar

Coherent Doppler Wind LIDAR is widely used in aerospace safety,wind power generation,weather forecast,and national defense due to its excellent system performance.It achieves wind speed measurement based on the Doppler effect,therefore,the performance of the wind LIDAR system is affected by the accuracy of Doppler Frequency Shift Estimation.To meet the requirements of high-precision measurement of wind speed in production and living,the engineering Doppler Frequency Shift Estimation Technology becomes the key point of the research.This thesis aims to improve the accuracy of Coherent Wind LIDAR in wind speed measurement,aiming at the problems of the echo signal being disturbed by noise,low signal-to-noise ratio,and engineering implementation of the Doppler Frequency Shift Estimation Algorithm into research.Through the study of Doppler Frequency Shift Estimation theory and algorithm,the thesis completes the hardware implementation of frequency estimation via a comprehensive algorithm combined with Autocorrelation Detection,Welch Power Spectrum Estimation,and Energy Centrobaric Correction method,and the effectiveness of the algorithm is verified by simulation analysis and experiments.The main research contents of this thesis are as follows:(1)Research the basic principles of LIDAR wind measurement and the implementation methods of related detection; analyze the noise source in the radar system by the LIDAR equation; propose the main performance parameters of Coherent Doppler Wind LIDAR and analyze factors.(2)Research the performance of common Doppler Frequency Shift Estimation algorithms,and through the analysis of this performance,a comprehensive algorithm design of Doppler frequency shift estimation combining Autocorrelation Detection,Welch Power Spectrum Estimation,and Energy Centrobaric Correction method is completed,and the effectiveness of the algorithm is verified by MATLAB simulation.(3)Based on the FPGA hardware platform,the hardware design of the Autocorrelation Detection module,the Welch Power Spectrum Estimation module,and the Energy Centrobaric Correction method module are implemented by Verilog HDL language,and the FPGA implementation of the comprehensive algorithm scheme is completed,and the effectiveness of the comprehensive algorithm is verified by Vivado functional simulation.(4)Based on the theoretical research,the design of the continuous wave modulation Coherent Doppler Wind LIDAR system is completed,and the wind measurement LIDAR experimental system is built for experimental verification.The experimental results show that under the experimental conditions of this thesis,the wind speed measurement error can reach 0.27m/s in the distance range of 20 meters.