It was located to the position fixing device null terminal which uses the breakdown position fixing manner, and this manner of the optical transmission link

摘要

PROBLEM TO BE SOLVED: To determine a failure position by providing a coherent detection type reflectometer on a terminal, and transmitting a measured pulse and a load signal connected to the measured pulse to a transmission link. ;SOLUTION: A branch unit 3 inserted to a transmission link L between trunk terminals 1, 2 can extract an optical carrying signal, modulated to a prescribed wavelength, for example, λ i for a branch terminal 4 of the sum Σλi of wavelengths transmitted from the trunk terminal 1. When the function of the transmission link L is inspected, a coherent detection type reflectometer 5 is provided in the transmission trunk 1, and a measured pulse I of a prescribed wavelength is transmitted by the transmission link L according to the reflectance. A load signal C having a wavelength λc different from that used for information transfer by the transmission link L is inserted between continuous pulses, so that a response signal of sufficient quality can be provided by a heterodyne receiver 6 included in the reflectometer 5. Thus, the transmission link L and a link L1 can be inspected, and the position of an existing failure can be determined by the reflectometer 5.;COPYRIGHT: (C)1999,JPO