Research On Doppler Frequency Estimation Of Coherent Wind Lidar

Coherent wind lidar is a new type of atmospheric remote sensing device that can obtain the distribution of three-dimensional wind field through the Doppler effect of atmospheric wind field motion.It is characterized by high precision and spatio-temporal resolution.It is widely used in the ballistic correction of battlefield rocket projectile,monitoring of aircraft carrier wake vortices,weather forecasting,wind power generation,and monitoring of changes in the instantaneous wind field at short distances at the airport.Wind field detection system of laser wind radar generally has the characteristics of low signal-to-noise ratio of echo signal and less observation data at high distance resolution,which will affect the high-precision estimation of Doppler frequency and reduce the performance of wind field detection system.How to carry out research about Doppler frequency estimation theory and algorithm under the above input restrictive conditions,improve the accuracy of frequency estimation is very important to ensure the performance of wind measurement radar.In this paper,the Doppler frequency estimation based on coherent accumulation and spectral interpolation is studied.The software simulation and hardware implementation of the estimation scheme are completed.The test platform of the wind radar system is built,and the experimental verification is completed.The main contents of this paper include:First,the basic theory and working principle of wind lidar are introduced,and the performance of Doppler frequency technique commonly used is analyzed and discussed.Second,a Doppler frequency estimation scheme based on coherent accumulation and spectral interpolation is designed,and the performance parameters are analyzed through simulation.At the same time,the applicability of the estimation scheme under Rice channel is analyzed.Third,the Verilog language is used to implement FPGA programming,and Modelsim simulation verifies the effectiveness of the Doppler frequency estimation module.Fourth,the experimental platform of wind lidar system is set up.The test verification results show that the Doppler frequency shift estimation accuracy reaches 0.4MHz and the corresponding radial wind speed accuracy is 0.31m/s when the distance resolution is 24 m and the time resolution is 0.25 s.The result shows that the scheme designed by the paper is feasible and effective.