激光雷达截面测量中大气后向散射补偿技术研究

发布时间：2018-05-08 18:43

本文选题：激光雷达散射截面 + 大气后向散射　；参考：《西安电子科技大学》2014年硕士论文

【摘要】：激光雷达主要工作在户外甚至是战场环境,既要面对复杂的天气情况和障碍物的干扰,又要应对复杂工作环境的突发变化。尤其在激光雷达散射截面的测量中,探测目标对激光信号的后向散射回波信号本身就相当微弱,且要受到接收系统自身的系统噪声以及激光在大气中传输产生的杂散光等背景噪声的影响,回波信号极其难以探测甚至可能出现被噪声淹没的情况。激光在大气中传输,产生的大气后向散射光是可以预见的能直接影响激光雷达探测性能的主要噪声之一。通过研究激光的大气后向散射问题可以探索消除大气后向散射影响的新方法,从而降低总体噪声,改善信噪比,提高激光雷达散射截面测量的可行性和准确性。这对促进激光雷达散射截面测量中微弱信号探测技术的完善和提高有较为重要的意义。基于激光雷达散射截面的基本理论和测量的基本过程,本文从大气介质的空间组成出发,分析了激光在大气中传输时产生大气后向散射的原因,给出了激光大气后向散射的定义,并对大气后向散射对激光雷达散射截面测量过程中的影响做了详尽的分析和讨论。进而,建立了激光大气后向散射理论模型,并对该模型进行了计算和分析,给出了不同的距离范围内产生的大气后向散射相对总大气后向散射所占的比重,为消除大气后向散射的研究提供了理论指导和数据支撑。然后,提出了基于空间滤波的消除大气后向散射影响的新方案,并应用新实验方案在雾霾天气和晴朗天气两种天气条件下进行了模拟实验,对实验结果进行了分析讨论。最后,将理论模型和实验方案进行了对比分析结果显示,能够进入探测系统的大气后向散射主要集中在一定的距离范围内。将二者相结合,对一个实际测量的外场实验进行了工程应用的分析发现,可以通过调节发射和接收系统的距离间隔来控制绝大部分的大气后向散射进入探测系统,而剩余的仍然能产生影响的大气后向散射完全可以用本文提出的空间滤波的方法进行控制。本文的研究思路是先根据大气后向散射理论建立理论模型,再对外场实验数据进行分析来完善和优化理论模型,并提出了基于空间滤波的消除大气后向散射的实验方法,实现了对大气后向散射影响的消除,大大提高激光雷达散射截面测量的可行性和准确性。然而,在本文的研究中仍然存在着理论模型建立背景与工程实际有差异的不足,在接下来的工作中仍需要继续在尊重工程实际的前提下深入完善理论模型,改进和提高实验分析办法,做好对工程实际更细致的应用指导。另外实验的天气条件与理论天气条件的差异带来的误差需要做进一步的研究,以求进一步缩小理论和实测的误差。
[Abstract]:The lidar mainly works in the outdoor and even battlefield environment. It not only faces the complex weather and obstacle interference, but also deals with the sudden changes of the complex working environment. Especially in the measurement of the laser radar cross section, the backscattering echo signal of the target to the laser signal itself is very weak. It is also affected by the system noise of the receiving system and the stray light produced by the laser in the atmosphere. The echo signal is extremely difficult to detect and even may be submerged by the noise. The atmospheric backscattering light produced by laser propagation in the atmosphere is one of the main noises which can directly affect the detection performance of lidar. By studying the atmospheric backward scattering of laser, a new method to eliminate the influence of atmospheric backscattering can be explored, which can reduce the total noise, improve the signal-to-noise ratio, and improve the feasibility and accuracy of laser radar cross section measurement. It is of great significance to improve the detection technology of weak signal in the measurement of laser radar cross section. Based on the basic theory of laser radar cross section (LRCS) and the basic process of measurement, this paper analyzes the causes of atmospheric backscattering when laser propagates in the atmosphere from the space composition of atmospheric media. The definition of laser atmospheric backscattering is given, and the influence of atmospheric backscattering on the measurement of laser radar cross section is analyzed and discussed in detail. Furthermore, the theoretical model of laser atmospheric backscattering is established, and the calculation and analysis of the model are carried out. The proportion of atmospheric backscattering relative to total atmospheric backscattering in different distance range is given. It provides theoretical guidance and data support for the study of eliminating atmospheric backscattering. Then, a new scheme based on spatial filtering to eliminate atmospheric backscattering is proposed, and the experimental results are analyzed and discussed under two weather conditions: haze weather and sunny weather. Finally, the theoretical model and the experimental scheme are compared and analyzed. The results show that the atmospheric backscattering which can enter the detection system is mainly concentrated in a certain range of distances. By combining the two methods, the engineering application of an actual field experiment is carried out. It is found that most of the atmospheric backscattering can be controlled into the detection system by adjusting the distance between the transmitting and receiving systems. The remaining backscattering can be controlled by the spatial filtering method proposed in this paper. The research idea of this paper is to establish a theoretical model based on the atmospheric backscattering theory, then to analyze the experimental data of the external field to perfect and optimize the theoretical model, and to propose an experimental method to eliminate the atmospheric backscattering based on spatial filtering. The effect on atmospheric backscattering is eliminated, and the feasibility and accuracy of LRCS measurement are greatly improved. However, in the research of this paper, there are still some differences between the background of the theoretical model and the engineering practice. In the following work, we still need to further improve the theoretical model on the premise of respecting the engineering reality. Improve and improve the method of experimental analysis, and make a more detailed application guidance to engineering practice. In addition, the errors caused by the difference between the experimental weather conditions and the theoretical weather conditions need to be further studied in order to further reduce the theoretical and measured errors.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN958.98

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