Design Of The Large Dynamic Range OTDR Based On ARM CORTEX-A8

Along with the flourish development of optical communication,the requirements for optical fiber are going up very fast speed,so as the development of optical fiber measurement skill.OTDR is the abbreviation of Optical Time Domain Reflectometer,it’s used in the field of optical fiber communication for test maintenance.OTDR main role is to find out the event point in the fiber such as breakpoints, loss points and so on. Such research carried out for dynamic, portable OTDR, can improve the related technology of China’s enterprises,and promote the development of the optical fiber communication in China.In this paper,I summarizes the development history of OTDR,the transmission properties of optical fiber,the basic working principle and the overall diagram of OTDR.then the design of embedded systems mainly ARM CORTEX-A8chip S5PV210to build hardware environment,including OTDR transceiver signal circuits,such as the laser driver circuit, APD bias circuit, Low noise amplifier circuit and A/D conversion circuit.For the Embedded software,I design some drive for OTDR, such as led,lcd,nandflash,norflash and network.I also design an detection algorithm for OTDR,and use QT for interface of OTDR.At last I test the OTDR,the measured results meet the technical indicators. Dynamic range of OTDR reaches40dB/38dB (1310nm/1550nm),1m events blind area and4m Attenuation blind area,as Ranging accuracy±(1m+1sample interval+0.0025%distance)), Waveform data storage capacity of the machines is greater than800, while2G SD card more than65500paintings.