摘要
针对自发布里渊散射信号微弱、系统信噪比低、导致系统传输距离短的问题,提出了一种基于提升小波阈值联合累加平均降噪的方案,增大了系统的测量距离。理论分析了自发布里渊散射信号特征,选择了合适的小波基、分解层数、阈值规则和阈值函数。搭建了实验平台,对所提方案的有效性进行了验证,并与仅累加平均降噪的结果和累加平均联合传统小波阈值降噪的结果进行了对比。结果表明,相比仅累加平均降噪法,本文提出的累加平均联合提升小波阈值降噪法将传感距离由16.62 km提升到了39.45 km,而处理时间仅增加了2.22 s,基本满足测量的实时性要求;与累加平均联合传统小波阈值降噪方法相比,本文算法将传感距离提升了0.63 km,且处理时间减少了0.69 s。因此,本文提出的方案更适用于长距离BOTDR系统。
Objective Brillouin optical time-domain reflectometer(BOTDR)is employed in numerous fields with practical applications owing to its various advantages such as measuring multiple physical parameters,long sensing distance,and single-end measurement.However,Brillouin backscattered signals become weak along the fibers.Moreover,noises can be introduced by optical or electrical components in the BOTDR system,resulting in poor signal-to-noise ratio(SNR)as well as difficulty in accurately measuring the Brillouin frequency shift for long fiber,which limits the transmission distance.Reducing noise to enhance SNR is an essential for solving the problem.Traditional denoising methods include cumulative average denoising,traditional wavelet threshold denoising,and lifting wavelet threshold denoising.The cumulative average denoising method has limitations such as the time of accumulation and the storage capacity of the hardware.Meanwhile,whether traditional wavelet threshold denoising or lifting wavelet threshold denoising,they depend heavily on the characteristics of the signal and choice of parameters,such as the wavelet basis,wavelet decomposition layer,threshold rule,and threshold function.Therefore,for low SNR signals,these two methods are combined with other methods to achieve the expected denoising results.Considering the good denoising performance of the cumulative average method and the short denoising time of lifting wavelet transform,a novel denoising scheme combining both lifting wavelet threshold and the cumulative average is proposed to improve the measurement distance.Methods A denoising method for the BOTDR system that combines the lifting wavelet threshold with cumulative average is presented.The characteristics of spontaneous Brillouin scattering signals are analyzed.Then,we introduce the principle of lifting wavelet transform and discuss its denoising flowchart(Fig.2).Furthermore,the parameters of the wavelet threshold denoising suitable for the BOTDR signal are analyzed and optimized through simulations.This
作者
王晨
席丽霞
张阳安
袁学光
张晓光
单丽楠
肖振宇
李璇
Wang Chen;Xi Lixia;Zhang Yang’an;Yuan Xueguang;Zhang Xiaoguang;Shan Linan;Xiao Zhenyu;Li Xuan(State Key Laboratory of Information Photonics and Optical Communications,Beijing University of Posts and Telecommunications,Beijing 100876,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2021年第17期89-97,共9页
Chinese Journal of Lasers
基金
国家自然科学基金(61875247,61527820)。
关键词
光通信
布里渊散射信号
累加平均
提升小波
小波阈值降噪
optical communications
Brillouin scattering signal
cumulative average
lifting wavelet
wavelet threshold denoising
