Patent ID: 7167237
Filing Date: 2007-01-23
Classification: G01M,H04B

Abstract:
1. A fault searching method for an optical line which searches for a fault in an optical line connected with an optical fiber carrying out data transmission between from a transmission apparatus at a center station side via an optical divider such as a passive optical network (PON) up to a user optical terminal comprising: preparing an optical time domain reflectometer (OTDR) which carries out a test for the optical fiber based on backward scattering light or return light from the optical fiber by making test light be incident into the optical fiber; detaching a terminal portion of the optical line at an inside of the user optical terminal from the inside of the user optical terminal, and connecting the OTDR to the terminal portion of the optical line; making at least one of test light with a wavelength different from a wavelength of light used for data transmission in the optical line, and test light whose peak level is less than or equal to a predetermined level be incident upon the terminal portion of the optical line from the OTDR; and searching for a fault in the optical line from the user optical terminal side by detecting backward scattering light or return light from the optical line which is obtained based on the incidence of the test light by the OTDR.