公开(公告)号：US11522606B2

公开(公告)日：2022-12-06

申请号：US17285719

申请日：2019-11-14

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Yoshifumi Wakisaka ,  Daisuke Iida ,  Keiji Okamoto ,  Hiroyuki Oshida

IPC: H04B10/07 ,  H04B10/071

Abstract: It is an object to enable offline measurement with a high SN ratio of the phase of scattered light of an optical fiber to be measured in an optical receiving system for real-time measurement (direct measurement). The phase measurement method according to the present invention performs coherent detection of scattered light using a 90-degree optical hybrid, obtains an estimated quadrature component value by averaging a measured quadrature component value that is directly measured and a calculated quadrature component value obtained by Hilbert transforming a measured in-phase component value that is directly measured, obtains an estimated in-phase component value by averaging the measured in-phase component value and a calculated in-phase component value obtained by inverse Hilbert transforming the measured quadrature component value, and calculates the phase of scattered light based on the estimated quadrature component value and the estimated in-phase component value.

公开(公告)号：US20220326005A1

公开(公告)日：2022-10-13

申请号：US17634435

申请日：2020-02-13

Applicant: Nippon Telegraph and Telephone Corporation

Inventor： Tatsuya Okamoto ,  Daisuke Iida ,  Hiroyuki Oshida

IPC: G01B11/16

Abstract: The present disclosure provides a device that accurately measures vibration at a designated position of a sensing fiber without using digital signal processing to compensate for distance fluctuation. Digital signal processing for correcting fluctuation of a measurement distance due to a frequency offset of a beat signal due to vibration, which is a measurement target, is simplified. In the present disclosure, vibration at a designated position of the sensing fiber is accurately measured without using the digital signal processing to compensate for the distance fluctuation. A spectrum analysis length of an electrical field E(τn) of backscattered light is set to be larger than a delay deviation Nd due to frequency modulation caused by dynamic strain. An index of tolerance of vibration distribution measurement to the delay deviation Nd is also clarified.

公开(公告)号：US11280668B2

公开(公告)日：2022-03-22

申请号：US17256532

申请日：2019-06-19

Applicant: Nippon Telegraph and Telephone Corporation

Inventor： Kunihiro Toge ,  Daisuke Iida ,  Shingo Ono ,  Yoshifumi Wakisaka ,  Tetsuya Manabe

IPC: G01H9/00 ,  G02B6/35

Abstract: A distributed optical fiber vibration measurement device includes a phase constant difference computation unit causing the first backscattered light generated at the points of a plurality of optical fibers under test that are integrated to interfere with another light to obtain two AC components and determining a phase constant difference from the two AC components, a phase distribution data creation unit comparing amplitudes between the two AC components obtained by causing the first backscattered light generated at the points of the optical fibers under test to interfere with the other light and selecting, for each of the points, phase data regarding one of the two AC components having a larger amplitude to create phase distribution data with the phase data, and a vibration measurement unit identifying an optical path length difference between any two points of the optical fiber under test to measure vibration of the optical fiber under test.