相干多普勒测风激光雷达关键技术研究

发布时间：2019-06-06 00:53

【摘要】：大气风场的精确观测在气象、军事、航空航天等领域受到越来越多的关注。1550nm全光纤相干多普勒测风激光雷达因为其人眼安全,体积小,测风精度高,时间和空间分辨率氋等优点,非常适合于风速实时监测且机动性高、隐蔽性好,近些年来成为国内外研究的热点。本论文对1550nm波段的相干多普勒测风激光雷达关键技术进行了研究,主要内容如下:本文首先分析了测风激光雷达在气象、军事、航天航空等领域的应用,并总结了国内外激光雷达的研究过程,明确课题研究意义;第二部分主要分析了相干多普勒测风激光雷达原理。首先,介绍了测风激光雷达系统组成,然后结合相干多普勒测风激光雷达原理和系统框图分析了相干多普勒测风激光雷达方程,对激光雷达方程中的关键参数包括标准大气条件下的后向散射系数和大气透过率进行了仿真;通过介绍相干探测原理,推导出相干信号表达式,进而给出激光雷达信噪比概念,并依据天线定理,使用后向传播本振光对信噪比进行推导给出信噪比表达式,通过分析信噪比表达式,给出影响信噪比的关键参数:外差效率,天线效率表达式。第三部分对影响相干多普勒测风激光雷达系统误差的因素进行了分析,包括激光器性能,频谱分辨率,探测信噪比对测频精度的影响。通过对系统误差的分析,决定系统各参数及探测距离。第四章对频率提取算法、扫描系统、望远镜设计关键技术进行了具体分析。对于频率提取算法,通过对脉冲对算法,改善型脉冲对算法,补零FFT及最大似然估计算的分析,得出补零FFT算法适合相干多普勒测风激光雷达实时风速测量的可行性;通过仿真,对扫描系统具体参数进行了分析,确定扫描系统具体参数;利用天线效率结论,以及信噪比仿真,对望远镜需求进行分析,设计了一款符合需求的透射式望远镜;第五章对搭建的相干多普勒测风激光雷达进行了试验验证和外场试验。通过试验台临时搭建系统,验证激光雷达原理可行性,并通过转速马达对相干多普勒测风激光雷达速度测量进行初期标定,试验台完成功能性测试后,进行外场测试,基本实现了测风功能。第六章对研制工作进行总结,并指出工作的不足之处。并指出了接下来需要完成工作。
[Abstract]:More and more attention has been paid to the accurate observation of atmospheric wind field in meteorology, military, aerospace and other fields. 1550 nm all-fiber coherent Doppler wind lidar is safe in human eyes, small in size and high in wind measurement accuracy. The advantages of time and spatial resolution are very suitable for real-time wind speed monitoring, high maneuverability and good concealment. In recent years, it has become a hot research topic at home and abroad. In this paper, the key technologies of coherent Doppler wind lidar in 1550nm band are studied. The main contents are as follows: firstly, the application of wind lidar in meteorology, military, aerospace and other fields is analyzed. The research process of lidar at home and abroad is summarized, and the significance of the research is clarified. In the second part, the principle of coherent Doppler wind lidar is analyzed. Firstly, the composition of wind lidar system is introduced, and then the equation of coherent Doppler wind lidar is analyzed according to the principle and system block diagram of coherent Doppler wind lidar. The key parameters of lidar equation, including backscattering coefficient and atmospheric transmittance under standard atmospheric conditions, are simulated. By introducing the principle of coherent detection, the expression of coherent signal is derived, and then the concept of SNR of lidar is given. According to the antenna theorem, the SNR expression is derived by using backward propagating local oscillator light. By analyzing the expression of signal-to-noise ratio (SNR), the key parameters affecting SNR are given: heterodyne efficiency and antenna efficiency expression. In the third part, the factors affecting the system error of coherent Doppler wind lidar are analyzed, including laser performance, spectrum resolution and the influence of signal-to-noise ratio (SNR) on the accuracy of frequency measurement. Through the analysis of the system error, the parameters and detection distance of the system are determined. In the fourth chapter, the frequency extraction algorithm, scanning system and the key technology of telescope design are analyzed in detail. For the frequency extraction algorithm, through the analysis of pulse pair algorithm, improved pulse pair algorithm, zero compensation FFT and maximum likelihood estimation, it is concluded that the zero compensation FFT algorithm is suitable for real time wind speed measurement of coherent Doppler wind lidar. Through simulation, the specific parameters of the scanning system are analyzed, and the specific parameters of the scanning system are determined. By using the conclusion of antenna efficiency and signal-to-noise ratio (SNR) simulation, the requirements of the telescope are analyzed, and a transmission telescope is designed to meet the requirements. In chapter 5, the experimental verification and field test of coherent Doppler wind lidar are carried out. Through the temporary construction system of the test-bed, the feasibility of lidar principle is verified, and the velocity measurement of coherent Doppler wind lidar is calibrated by rotating speed motor. After the functional test of the test-bed is completed, the external field test is carried out. The function of wind measurement is basically realized. The sixth chapter summarizes the research work and points out the shortcomings of the work. It is pointed out that the next work needs to be completed.
【学位授予单位】：中国航天科技集团公司第一研究院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN958.98

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