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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。
Aiming at the characteristics of the noise contained in the lidar echo signal, a wavelet packet mean thresholding method which can effectively de-noise the lidar echo signal is proposed and discussed in detail. The method achieves wavelet packet denoising by finding the threshold of each node of the optimal wavelet packet basis and averaging it as a global threshold. In order to verify the effectiveness of the proposed method, the simulated signal containing Gaussian white noise is simulated and noise-canceled, and the atmospheric echo signal actually detected by Mie scattering lidar system is denoised. At the same time, this method is compared with wavelet denial of global threshold and denoising effect of wavelet packet default threshold. The simulation results and experimental results show that the average threshold based wavelet packet denoising method can effectively reduce the noise contained in the lidar echo signal, and its denoising effect is significantly better than the other two wavelet analysis methods.