Fiber Fault Measurements Using Traffic Signal In Passive Optical Networks

In recent years,with the rapid development of mobile communication networks and fiber-optic communication technologies,especially the emergence of the fifth-generation mobile communication technology(5G),the demand for fiber-optic cables has been greatly increased,and a large number of optical fiber communication links have been laid in various countries around the world.At the same time,due to the advantages of large transmission capacity,ultra-long transmission distance and ultra-high transmission rate of optical fiber communication,optical fiber communication systems are applied in important fields such as scientific research,commerce,and military.As a carrier for transmitting signals in a communication transmission system,an optical fiber will have serious consequences for information transmission in the event of a failure.Therefore,how to quickly and accurately determine the exact location of the fiber link fault point in the fiber-optic communication network is very necessary.At present,the traditional optical time domain reflectometer(OTDR)is the main instrument for diagnosing the fault point of the fiber link,but theinstrument has many defects in principle: the use of OTDR to diagnose the fault point in the fiber link needs to temporarily interrupt the normal operation of the optical network.Communication service;when the communication signal in the optical communication network and the pulse signal from the optical time domain reflectometer are simultaneously transmitted in the optical fiber,stimulated Raman scattering occurs,which affects the normal communication service of the system.According to the above-mentioned problems in the previous research results,the research group proposed to use the communication signal itself in the optical network to realize the online real-time detection of the fiber breakpoint through the correlation detection method.This solution can not only realize the real-time measurement of single fault point,but also Multiple fiber breakpoints can be diagnosed simultaneously.In this paper,the optical time domain reflectometry method based on the communication signal itself is introduced.The collected data is analyzed and processed by the wavelet transform denoising method and the permutation entropy extraction method.The measurement results are optimized,the measurement accuracy is improved,and the detection cost is saved.Passive optical network fiber fault detection provides a new idea.Among them,the data analysis results permutation entropy algorithm have been included in the Journal of Shenzhen University.In this paper,based on the communication signals in the optical network,the real-time detection of fiber-optic faults in fiber-optic links is realized.Theprinciple of measurement is introduced theoretically.The feasibility of the scheme is verified by experiments,and the reasons for the inaccuracy of the measurement results are analyzed.Finally,the wavelet transform and permutation entropy algorithm are introduced to optimize the experimental results and improve the accuracy of the measurement.The main work is as follows:1.Introduced the development history of optical fiber communication and the characteristics of optical fiber transmission,and focused on the analysis of various methods of fiber fault diagnosis.2.Based on the research basis of the research group,the principle of detecting the fiber fault by the communication signal is introduced in detail,and the experimental platform is built according to the principle.The reference signal and the reflected signal are collected through the experimental platform.The characteristics of the communication signal are analyzed and preliminary experiments are carried out.Preliminary experimental results and analysis of the causes of the errors.3.The basic principles of wavelet transform algorithm and permutation entropy algorithm are introduced,and the collected data are processed by two algorithms.The wavelet transform algorithm can effectively remove the influence of the interference noise signal,and the permutation entropy algorithm can extract the random signal in the communication signal.Finally,we accurately measure the fault point of the fiber,and the fiber faultmeasurement is well completed.