The Experimental Research Of Real-time Coherent Wind Lidar Signal Preprocessing Based On FPGA

1550 nm coherent doppler lidar has widely application prospect and important research significance in the safeflying,meteorological research,and exploitation of wind power,etc.on account of its advantages of higher range resolution,higher speed resolution,higher maximum permissible exposure for human eyes,and the ability to achieve clear sky detection and 3D detection.With the atmospheric wind field changing rapidly,the real-time signal pre-process of coherent laser radar is necessary especially when it comes to flying safely.On the purpose of real-time processing,the paper have designed the signal preprocessing system of coherent wind lidar based on FPGA.Firstly,the paper expounds background and significance,and summarizes both domestic and foreign development of coherent lidar and data processing algorithms.In this paper,the methods are divided into two aspects of power spectrum estimation and spectrum correction in the process of simplifying maximum likelihood estimation.Secondly,the basic principle of coherent laser radar detecting wind field and signal processing is described in detail.On the basis of the coherent laser radar in this laboratory,a set preliminary plan of data process is prepared,and the principle of FFT and spectrum correction is mainly studied.Thirdly,after the spectrum correction methods are verified by MATLAB simulation,the ratio correction method is chosen.Hardware circuit and FPGA procedure are designed to realize the purpose of real-time signal preprocess.The whole circuit is completed by an FPGA chip of Xilinx XC7K70 T model,an 12 bit AD chip of500 MSPS conversion rate,CPCI bus and so on.High speed AD collection,32 channels parallel FFT and self-correlation accumulation are designed on FPGA.Finally,the experiment of detecting hard target's velocity and wind field.With the experimental velocity data of servo motor's blades processed by MATLAB,it is concluded that the laser radar's velocity measurement precision can reach less than 1m/s,and the ratio correction algorithm can get better effect.But the velocity measurement error increase by FPGA and the maximum was 1.25 m/s.After FPGA processes measuring wind velocity data,the wind speed information is observed in the accumulation results of different distances,and the wind measurement data processing plan using FPGA is verified basically.