基于FPGA的相干测风激光雷达实时信号预处理实验研究

发布时间：2018-07-05 09:16

本文选题：相干测风激光雷达 + 信号预处理　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：1550 nm相干测风激光雷达具有距离和速度分辨率高、人眼耐受性强以及能实现小型化和晴空三维探测的优点,使其在低空安全、气象研究和风能开发等方面具有广泛地应用前景和重要地研究意义。大气风场瞬息万变,尤其在关系到飞行安全时,实现相干激光雷达信号的实时预处理十分必要。本文选用FPGA对相干测风激光雷达的信号预处理部分进行设计,来实现实时处理的目的。首先,阐述了本文的研究背景和意义,并且从相干测风激光雷达和数据处理算法的国内外发展两个方面进行了综述,给出了分析。这里把简化最大似然估计的各种方法分成功率谱估计和频谱校正两个方面进行介绍。接着,详细地叙述了相干激光雷达探测风场和信号处理的基本原理。在本文相干激光雷达的基础上拟定出一种数据处理的初步方案,其中重点研究了快速傅里叶变换原理和频谱校正的原理。然后,通过MATLAB仿真验证了频谱校正方法,对比分析后本文选择比值方法。为了达到信号的实时预处理的目的,选择FPGA进行了硬件电路设计和软件设计。在设定硬件电路各个功能的前提下,选择Xilinx公司的XC7K70T型号的FPGA芯片、12位500 MSPS的AD芯片和CPCI总线等设计完成了电路。在FPGA的内部软件设计部分,主要完成了高速AD采集、32路并行FFT运算和自相关累加等。最后,本文进行了硬目标测速实验和外场风场探测实验。利用MATLAB处理测量伺服电机带动叶片的速度的实验数据,经分析得出本激光雷达测速精度能够达到小于1 m/s,并且选用的比值校正算法能得到较好的效果。但是基于FPGA计算结果的误差则有所增加,最大是1.25 m/s。在测风实验中,用FPGA处理实验数据,得到不同距离门处的累加结果,并对其观察得出风速信息。通过本次测风实验,基本验证了FPGA处理测风数据方案的可行性。
[Abstract]:The 1550 nm coherent wind lidar has the advantages of high range and velocity resolution, strong human eye tolerance, miniaturization and three dimensional clear sky detection, which makes it safe at low altitude. Meteorological research and wind energy development have broad application prospects and important research significance. The atmospheric wind field changes rapidly, especially when the flight safety is concerned, it is necessary to realize the real-time preprocessing of coherent lidar signal. In this paper, FPGA is used to design the signal preprocessing part of coherent wind lidar to realize the purpose of real time processing. Firstly, the research background and significance of this paper are described, and the development of coherent wind lidar and data processing algorithms are summarized and analyzed. In this paper, the simplified maximum likelihood estimation methods are introduced in two aspects: success rate spectrum estimation and spectrum correction. Then, the principle of detecting wind field and signal processing by coherent lidar is described in detail. Based on the coherent lidar in this paper, a preliminary scheme of data processing is developed, in which the principle of fast Fourier transform and the principle of spectrum correction are mainly studied. Then, the spectrum correction method is verified by MATLAB simulation, and the ratio method is chosen after comparison and analysis. In order to achieve the goal of real-time signal preprocessing, FPGA is selected to design the hardware circuit and software. On the premise of setting each function of the hardware circuit, the circuit is designed by selecting XC7K70T FPGA chip of Xilinx company and AD chip of 500MSPS with 12 bits and CPCI bus. In the internal software design of FPGA, 32 channels parallel FFT operation and autocorrelation accumulation are accomplished. Finally, the velocity measurement experiment of hard target and the wind field detection experiment are carried out in this paper. By using MATLAB to deal with the experimental data of measuring the speed of the blade driven by the servo motor, it is concluded that the accuracy of the lidar speed measurement can be less than 1 m / s, and the ratio correction algorithm selected can get better results. However, the error based on FPGA results is increased, the maximum is 1.25 m / s. In the wind measurement experiment, the experimental data are processed with FPGA, and the accumulated results at different distance gates are obtained, and the wind speed information is obtained by observing them. Through the wind measurement experiment, the feasibility of FPGA to deal with wind data is verified.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN958.98

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