OTDR(Optical Time Domain Reflectometer) is a precise photoelectric integrated instrument Which worked as Rayleigh scattering and back scattering generated by Fresnel reflection when light is transmitted in optical fiber. It is widely used in the maintenance and construction of optical cable lines, measure the length of optical fiber, transmission attenuation of optical fiber, joint attenuation and fault location.

Optical fiber and cable testing is an important technical means of optical cable construction, maintenance and urgent repair. OTDR is the most effective way to conduct the field monitoring and connection loss measurement evaluation of optical fiber connection. This method is intuitional, reliable and it can print the backscatter signal curve. In addition, the actual transmission distance from the station to each joint point can be measured accurately while monitoring. This is necessary for the maintenance, accurate fault finding and effective fault handling. It requires maintainer to master instrument performance, skilled operation skills, and accurately judge the characteristics of signal curve.