基于小波包分析的激光雷达信号消噪算法的研究

Noise Reduction in Lidar Signal Based on Wavelet Packet Analysis

针对激光雷达回波信号所含噪声的特点,提出并详细论述了一种能够对激光雷达回波信号进行有效消噪的小波包平均阈值变换方法。该方法通过求取最优小波包基的每个结点的阈值,并进行平均后作为全局阈值来实现小波包消噪。为了验证该方法的有效性,对包含高斯白噪声的模拟信号进行了仿真消噪,并对米氏散射激光雷达系统实际探测得到的大气回波信号进行了消噪处理。同时,将该方法与小波全局阈值消噪、小波包默认阈值的消噪效果进行了对比分析。仿真结果和实验结果表明,基于平均阈值的小波包消噪方法能够有效降低激光雷达回波信号中所含噪声,并且其消噪效果明显优于另外两种小波分析方法。

According to the characteristic of lidar-return noise,an effective de-noising method of wavelet packet based on average threshold is presented and described to reduce the lidar-return noise.In the method,the thresholds of every node of the best wavelet packet basis are acquired and averaged,and then the average value is used as a global threshold to quantize the decomposition coefficient of every node.To verify the feasibility of the de-noising method,some numerical simulations are carried out to reduce the Gauss white noise of the simulated signal,and also,the Mie lidar returns contaminated by noise are de-noised by the method.Moreover,the comparisons among the wavelet packet transform based on average threshold,wavelet transform based on global threshold and the wavelet packet transform based on default threshold are performed.Experiment results show that the method of wavelet packet based on average threshold is capable of effectively reducing the lidar return noise and the de-noising effect is better than other two methods.