Research On Portable Intelligent Optical Time Domain Reflectometry

Optical Time Domain Reflectometer(OTDR)is the main instrument to detect the status of optical fiber.Portable OTDR is widely used in field fiber optic cable maintenance.However,analyzing the OTDR curve need professional knowledge and experience,or will not locate the fault directly and accurately.In addition,due to the low performance and function,OTDR can not analysis the data with advance methods.And the maintenance center can’t get field measurement’s data timely,so the maintenance is inefficient.In view of these problems,this paper presents a portable OTDR improvement program.With the traditional portable OTDR designed,I also add the wireless file sharing function for the traditional portable OTDR.Then it can upload collected data to maintenance center or mobile terminal everywhere.The optical transmitter circuit and optical receiver circuit at hardware part is designed.Optical transmitter circuit need to output adjustable narrow pulse.Optical receiving circuit collect back propagation signal.The data is processed by FPGA first then display and share by ARM S5P4418.Waveform interface designed by QT and QWT frameworks.File sharing with maintenance center by FTP.Mobile terminal uses Bluetooth OBEX service for data upload.Result shows the portable intelligent OTDR I proposed can output variable narrow pulse.The minimum output pulse width is 10 ns.The system dynamic range is about28 dB and sampling resolution is 105 MHz.the distance resolution is about 2m,so the data size would be 64 KB when we test 60 km optical fiber.The overall power is about7 W and can use more than 8h.FTP transfer speed can reach 1MB/s,and Bluetooth OBEX file sharing speed is about 200KB/s,usually completed the transmission job within 1s,the system make up the lack of existing OTDR and improve the efficiency of fiber optic cable maintenance.