Efficient Lidar Signal Denoising Algorithm Using Variational Mode Decomposition Combined with a Whale Optimization Algorithm

Hongxu Li,Renxiang Mao,Xiaolei Dou,Zhenxing Liu,Zhenbo Yang,Fan Xu,Jianhua Chang,Shuyi Zhang,Luyao Zhang,Binggang Liu

doi:10.3390/rs11020126

Abstract

Although lidar is a powerful active remote sensing technology, lidar echo signals are easily contaminated by noise, particularly in strong background light, which severely affects the retrieval accuracy and the effective detection range of the lidar system. In this study, a coupled variational mode decomposition (VMD) and whale optimization algorithm (WOA) for noise reduction in lidar signals is proposed and demonstrated completely. The combination of optimal VMD parameters of decomposition mode number K and quadratic penalty α was obtained by using the WOA and was critical in acquiring satisfactory analysis results for VMD denoising technology. Then, the Bhattacharyya distance was applied to identify the relevant modes, which were reconstructed to achieve noise filtering. Simulation results show that the performance of the proposed VMD-WOA method is superior to that of wavelet transform, empirical mode decomposition, and its variations. Experimentally, this method was successfully used to filter a lidar echo signal. The signal-to-noise ratio of the denoised signal was increased to 23.92 dB, and the detection range was extended from 6 to 10 km.

Highlights

Lidar is a combination of traditional radar technology and modern laser technology and has the advantages of high resolution, wide detection range, and strong anti-interference ability [1].Its applications in atmospheric remote sensing detection, e.g., aerosol, cloud layer, and visibility, have become increasingly important [2,3]
The power of the lidar echo signal decays with the exponential attenuation of the aerosol extinction coefficient and the square of the distance between the lidar and the target according to the lidar equation, and the signal can be interfered with by noise from electric fluctuations and stray lights [4]
The lidar echo signal is susceptible to strong background sunlight noise, dark current noise, and thermal noise [5]

Summary

Introduction

Lidar is a combination of traditional radar technology and modern laser technology and has the advantages of high resolution, wide detection range, and strong anti-interference ability [1].Its applications in atmospheric remote sensing detection, e.g., aerosol, cloud layer, and visibility, have become increasingly important [2,3]. Lidar is a combination of traditional radar technology and modern laser technology and has the advantages of high resolution, wide detection range, and strong anti-interference ability [1]. The power of the lidar echo signal decays with the exponential attenuation of the aerosol extinction coefficient and the square of the distance between the lidar and the target according to the lidar equation, and the signal can be interfered with by noise from electric fluctuations and stray lights [4]. The lidar echo signal is susceptible to strong background sunlight noise, dark current noise, and thermal noise [5]. Useful signals are inevitably contaminated by noise, which will directly affect the effective working range and the detection precision.

Methods

Results

Conclusion