基于小波变换的激光雷达回波信号去噪方法研究

基于小波变换的激光雷达回波信号去噪方法研究(论文12000字)
摘要：激光雷达不仅在军事上具有重要的应用价值，在民用上也有诸多涉及。在实际应用中，激光雷达后向散射回波信号的强度随距离的平方衰减，当探测距离较大时，信号将淹没在较强的噪声之中。因此，如何有效地从强背景噪声中提取出有用信号至关重要。小波变换作为一种适用于处理非线性、非平稳信号的有效去噪方法，在激光雷达回波信号方面具有很好的应用。本论文针对激光雷达回波信号中的噪声特性，提出运用小波变换对激光雷达回波信号中的噪声进行去除。通过建立理想的模型，选择合适的小波基、分解层数和阈值，运用MATLAB进行仿真得到去噪后的结果，利用信噪比，比较去噪效果。实验结果表明，选择sym4小波的五层分解方法和db6小波的五层分解方法对激光雷达回波信号进行去噪有较好的效果。为了进一步验证小波去噪的优势，将其与经验模态分解去噪方法进行比较，表明了小波变换在回波信号去噪方面具有一定的优势。
关键词：激光雷达；小波变换；去噪；经验模态分解

Research on Denoising Method of Echo Signal of Lidar Based on Wavelet Transform
Abstract:Lidar has an important application value in the military, but also involved in civilian. In practical applications, the intensity of the backscattering echo signal of the lidar decays with the square of the distance, and when the detection distance is larger, the signal will be submerged in the stronger noise. Therefore, it is important to effectively extract useful signals from strong background noise. As an effective de-noising method for dealing with nonlinear and nonstationary signals, wavelet transform has a good application in lidar echo signal. In this paper, the noise in the lidar echo signal is removed by wavelet transform. Through the establishment of the ideal model, select the appropriate wavelet base, decomposition layer and threshold, using MATLAB to simulate the results obtained after de-noising, the use of signal to noise ratio, compared de-noising effect. The experimental results show that the five-layer decomposition method of sym4 wavelet and the five-layer decomposition method of db6 wavelet have good effects on de-noising lidar echo signal. In order to further verify the advantages of wavelet de-noising, it is compared with the empirical mode decomposition de-noising method, which shows that the wavelet transform has certain advantages in echo signal de-noising.
Key words: lidar; wavelet transform; denoising; empirical mode decomposition
 

目录
1引言    1
1.1 选题的意义与背景    1
1.2 国内外现状    1
2激光雷达理论基础    2
2.1 激光雷达的工作原理    2
2.2 激光雷达噪声特性    3
2.2.1 探测器噪声    3
2.2.2 信噪比    4
3小波去噪理论分析    5
3.1 小波函数    5
3.2 小波去噪原理    6
3.2.1 小波去噪问题的描述    6
3.2.2 信号与噪声在小波变换不同尺度上的传播特性    7
3.3 典型小波去噪方法    7
3.3.1阈值去噪    8
3.3.2 相关去噪    9
4激光雷达回波信号去噪方法研究    10
4.1 激光雷达回波信号的建立    10
4.1.1理想激光雷达回波信号的仿真    10
4.1.2 噪声模拟分析以及回波信号仿真模型的建立    11
4.2 小波阈值去噪仿真实验    12
4.2.1 小波阈值的选择    12
4.2.2 小波基函数的选择    13
4.2.3 小波分解层数的确定    15
4.2.4 总结    17
4.3 小波变换与EMD去噪对比实验分析    17
4.3.1 EMD分解原理    17
4.3.2 EMD去噪原理    18
4.3.3 实验对比分析    19
5结论    20
参考文献    20
致谢    23