Optical fiber monitoring method, and optical fiber monitoring system

Patent metadata

Field	Value
Publication number	US-11112332-B2
Application number	US-201916977882-A
Country	US
Kind code	B2
Filing date	Mar 5, 2019
Priority date	Mar 6, 2018
Publication date	Sep 7, 2021
Grant date	Sep 7, 2021

Abstract

An object of the present disclosure is to provide an optical fiber cable monitoring method and an optical fiber cable monitoring system capable of linking information obtained from a measurement result with information stored in a DB and accurately specifying a loss occurrence location on an optical fiber cable. The optical fiber cable monitoring method according to the present disclosure uses two types of optical fiber measurement techniques having different sensitivities. Each of closure locations on the optical fiber cable is acquired with a high-sensitivity measurement technique, and geographical location information and the closure locations on the optical fiber are linked in an arrangement order of the closures. Thus, an operator can recognize an actual location (geographical location information) of a closure that is linked to a location of a point of abnormality on the optical fiber cable when an abnormality in the closure is detected with a low-sensitivity measurement technique.

First claim

The invention claimed is:

1. An optical fiber cable monitoring method for monitoring a plurality of specific points arranged in a length direction on an optical fiber cable, the optical fiber cable monitoring method comprising:
acquiring, by an optical measurement in which information about a distance of the optical fiber cable is acquired by propagating a measuring light, distance information of the specific points on the optical fiber cable;
linking, by using an arrangement order of the specific points and geographical location information acquired in advance, the geographical location information with the distance information of the specific points for each of the specific points based on the arrangement order of the specific points;
abnormality-detecting, by an optical monitoring having lower sensitivity than the optical measurement, in which information about a distance of the optical fiber cable is acquired by propagating a monitoring-light, distance information on the optical fiber cable about a point of abnormality that occurs, in the optical fiber cable; and
acquiring, by using the geographical location information and the distance information of the specific points that are linked in the linking step, the geographical location information about the specific point corresponding to the point of abnormality based on the distance information about the point of abnormality detected in the abnormality-detecting step.

2. The optical fiber cable monitoring method according to claim 1 , wherein
the optical measurement in the step of acquiring the distance information is an optical time-domain reflection measurement in which the measuring light is an optical pulse that is less than or equal to a cutoff wavelength of the optical fiber cable, and the specific points are set by an occurrence point at which a loss is detected.

3. The optical fiber cable monitoring method according to claim 1 , wherein
the optical measurement in the step of acquiring the distance information is an optical time-domain reflection measurement in which, using Brillouin scattering caused by the measuring light, a lengthwise distribution of an amount of Brillouin frequency shift is measured, and the specific points are set by a singular point in the lengthwise distribution.

4. The optical fiber cable monitoring method according to claim 1 , wherein
the optical measurement in the step of acquiring the distance information is a Brillouin optical time-domain analysis measurement in which, by setting pump light of pulse light and probe light of continuous light as the measuring light, and changing a frequency difference between the pump light and the probe light, a lengthwise distribution of frequency characteristics of a Brillouin gain received by the probe light is measured, and the specific points are set by a singular point of the lengthwise distribution.

5. The optical fiber cable monitoring method according to claim 1 ,
wherein in the step of acquiring the distance information, the distance information of all the specific points is acquired.

6. The optical fiber cable monitoring method according to claim 1 ,
wherein, after the distance information about the point of abnormality is acquired in the abnormality-detecting step, the distance information of the specific points, which is from an incident end of the measuring light on the optical fiber cable at least to the point of abnormality, is acquired in the step of acquiring the distance information.

Assignees

• Nippon Telegraph & Telephone

Inventors

• Koshikiya Yusuke
• Nakamura Atsushi
• Noto Kazutaka
• Manabe Tetsuya

Classifications

• H04B10/071

  using a reflected signal, e.g. using optical time domain reflectometers [OTDR] · CPC title

• G01D5/35364

  using inelastic backscattering to detect the measured quantity, e.g. using Brillouin or Raman backscattering · CPC title

• G01M11/3127

  using multiple or wavelength variable input source · CPC title

• G01M11/3145 Primary

  Details of the optoelectronics or data analysis · CPC title

• G01M11/3172

  Reflectometers detecting the back-scattered light in the frequency-domain, e.g. OFDR, FMCW, heterodyne detection · CPC title