| 摘要 |
PURPOSE:To recognize a distance from an optical repeater to a broken point. CONSTITUTION:A cable is equipped with an optical fiber for measurement separately from a fiber for optical signal. A branching filter 2 branches the exciting beams of an exciting light source 1, one exciting beam is applied to a synthesizer 3 and the other exciting beam is applied to a branching filter 9. The branching filter 9 outputs this exciting beam to the optical fiber for measurement, inputs the exciting beam returned from a broken point P and applies it to a photodetector 12. Based on a reset signal outputted from a pulse current supply circuit 7 simultaneously with a pulse current for excitation and the electric pulse signal of the photodetector 12, a delay time calculation circuit 8 calculates the delay time of the returning exciting beam. Based on this delay time, a computing element 13 computes a distance to the broken point. |
