| 摘要 |
PURPOSE:To perform separation of an interrupted position in a light transmitting path used in optical fiber communications, by detecting the amount of reflection of light with a monitoring wavelength, which is inputted at the near end of the light transmitting path under test toward the far end. CONSTITUTION:At a subscriber's end of a light transmitting path 2, a filter 10, which separates light having a signal transmitting wavelength and light having a monitoring wavelength, is provided. A light signal from a signal transmitting circuit 1 is coupled to the light transmitting path 2 by a filter 12 and propagated. The light is separated by the filter 10 at the subscriber's end and received by a light receiving circuit 3. Meanwhile, light from a light-pulse transmitting circuit 7 in a center is inputted to the light transmitting path 2 by the filter 12 through an optical directional coupler 8. The light is selected by the filter 10 at the subscriber's end, reflected by a reflecting mirror 11, transmitted again in the light transmitting path 2 in the reverse direction, and received by a light-pulse receiving circuit 9 through the optical directional coupler 8. Based on the received time and amount of the reflected light, the presence or absence of a broken section and the distance to the broken section can be determined. |
