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公开(公告)号：US20250123138A1
公开(公告)日：2025-04-17
申请号：US18567483
申请日：2021-06-09
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Yoshifumi WAKISAKA , Daisuke IIDA , Yusuke KOSHIKIYA , Nazuki HONDA
Abstract: The present disclosure relates to a signal processing device that: acquires a signal obtained by repeatedly injecting a plurality of light pulses with different optical frequencies into an optical fiber, and by performing distributed acoustic sensing-phase (DAS-P); calculates a phase change, caused by vibration applied to a section of the optical fiber, using the acquired signal; removes, from the calculated phase change, a component regarding a repetition period of the same optical frequency of the plurality of light pulses; and calculates the vibration applied to the section of the optical fiber, using a phase change obtained by removing the component regarding the period.
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公开(公告)号：US20240192049A1
公开(公告)日：2024-06-13
申请号：US18286460
申请日：2021-04-14
Applicant: Nippon Telegraph and Telephone Corporation
Inventor： Tatsuya OKAMOTO , Daisuke IIDA , Yusuke KOSHIKIYA , Nazuki HONDA
IPC: G01H9/00
CPC classification number: G01H9/004
Abstract: An object of the present invention is to provide a cable test system, an analysis apparatus, a cable test method, and a program capable of recognizing a sag section of an overhead cable without sending a worker to a site.
A cable test system according to the present invention includes an optical fiber vibration distribution measurement apparatus 11 that acquires a vibration distribution waveform of an overhead optical fiber cable 50 to be tested, the vibration distribution waveform being represented in a time domain and a distance domain in a longitudinal direction, and an analysis apparatus 12 that calculates a propagation speed of vibrations propagating through the overhead optical fiber cable 50 from the vibration distribution waveform and detects, as a cable sag section, a section of the overhead optical fiber cable 50 in which the propagation speed is equal to or lower than a threshold value.-
公开(公告)号：US20230288191A1
公开(公告)日：2023-09-14
申请号：US18011563
申请日：2020-06-22
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Yoshifumi WAKISAKA , Shingo ONO , Daisuke IIDA , Hiroyuki OSHIDA
CPC classification number: G01B11/16 , G01D5/35361 , G01L1/24
Abstract: An object of the present disclosure is to measure, at a high sampling rate, a distribution of a vibration pattern applied to each core after being branched.
A strain change measurement apparatus according to the present disclosure inputs, at a reference time, first chirped pulsed light having a chirp having a frequency changing linearly with time to a measurement target optical fiber branched by a coupler, acquires a signal of first scattered light regarding the first chirped pulsed light, inputs, at each monitoring time, second chirped pulsed light having a chirp obtained by time axial inversion with respect to the first chirped pulsed light to the measurement target optical fiber to acquire a signal of second scattered light regarding the second chirped pulsed light, determines a shift amount allowing for maximization of a correlation between a waveform obtained by inverting the signal of the first scattered light around the time axis and further shifting and a waveform of the signal of the second scattered light, and uses the shift amount to calculate a change in strain amount in the measurement target optical fiber from the reference time to each monitoring time.-
公开(公告)号：US20230152170A1
公开(公告)日：2023-05-18
申请号：US17798172
申请日：2020-03-05
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Atsushi NAKAMURA , Daisuke IIDA , Hiroyuki OSHIDA , Tatsuya OKAMOTO , Tomokazu ODA , Yoshifumi WAKISAKA
CPC classification number: G01L1/242 , G01L5/0042
Abstract: An object of the present disclosure is to provide a method and an apparatus for acquiring curvature and torsion using an inexpensive sensor medium. Disclosed is a measurement apparatus including a fiber ribbon including a plurality of coated fibers arranged in parallel, a strain measurement unit that measures strain amounts of the plurality of coated fibers, and an arithmetic processing unit that calculates curvature and torsion of the fiber ribbon using a strain amount of a coated fiber arranged in a middle portion of the plurality of coated fibers and a strain amount of a coated fiber arranged in a marginal portion of the plurality of coated fibers.
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公开(公告)号：US20230144218A1
公开(公告)日：2023-05-11
申请号：US17926655
申请日：2020-06-03
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Tomokazu ODA , Hiroyuki OSHIDA , Daisuke IIDA , Atsushi NAKAMURA , Yuto SAGAE
IPC: G01M11/00
CPC classification number: G01M11/39
Abstract: The present invention has an object to provide an optical fiber testing method and an optical fiber testing device capable of measuring the delay ratio between the modes at each position of a fiber over a long distance in which a plurality of modes propagate.
An optical fiber testing method and its device according to the present invention, measure the change amount for the wave number k of a Brillouin Frequency Shift ν in stimulated Brillouin scattering generated in the same acoustic mode, with respect to each target propagation mode. Thereby, the ratio of the change amount measured at each propagation mode is acquired as the group delay ratio between the modes.-
Patent Agency Ranking
公开(公告)号：US20220149934A1
公开(公告)日：2022-05-12
申请号：US17430016
申请日：2020-01-29
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Tatsuya OKAMOTO , Daisuke IIDA , Hiroyuki OSHIDA
IPC: H04B10/071 , H04B10/2507
Abstract: The purpose of the present invention is to provide a device for optical frequency domain reflectometry and a method thereof that can measure a reflectance distribution with less spatial resolution degradation due to a phase noise, without using a wideband receiving system even when a long-distance measurement is performed. The device for optical frequency domain reflectometry according to the present invention is provided with a delay optical fiber for delaying a local light by a prescribed time, and obtains information on a relative delay of a backscattered light from an optical fiber under measurement with respect to the local light and information on the positivity and the negativity of a beat frequency by measuring an in-phase component and a quadrature component of a beat signal obtained by multiplexing the backscattered light from the optical fiber under measurement and the local light delayed by the delay optical fiber, so as to obtain a reflectance distribution in a longitudinal direction of the optical fiber under measurement based on these pieces of information.
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公开(公告)号：US20210223095A1
公开(公告)日：2021-07-22
申请号：US15734211
申请日：2019-05-29
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Yoshifumi WAKISAKA , Daisuke IIDA , Kunihiro TOGE , Tetsuya MANABE
Abstract: An object is to provide an optical fiber path search method, an optical fiber path search system, a signal processor, and a program that can be operated free of the effects of walls, supporting members, and the like so that only a signal generated by an acoustic wave propagating through the air can be extracted. An optical fiber path search system according to the present invention utilizes DAS and includes: a vibration source 304 configured to provide an acoustic wave to a predetermined region; a light reflection measurement device 305 configured to be connected to one end of an optical fiber 302 and configured to measure vibration of a change in an optical path length from the other end of the optical fiber 302 to a point in the optical fiber 302 due to the acoustic wave provided by the vibration source 304; and a signal processor 313 configured to extract a signal component in a high frequency region higher than a preset cutoff frequency from a signal of the vibration of the change in the optical path length measured by the light reflection measurement device 305 and calculate a distance between the vibration source 304 and the point in the optical fiber 302 using the signal component.
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公开(公告)号：US20250155277A1
公开(公告)日：2025-05-15
申请号：US18725072
申请日：2022-01-11
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Yoshifumi WAKISAKA , Hiroshi TAKAHASHI , Daisuke IIDA , Yusuke KOSHIKIYA
IPC: G01H9/00
Abstract: In order to achieve the above object, a signal processing method according to the present disclosure includes: a calculation step of calculating a phase change at each of points on a medium from a phase of a reflected signal generated by a pulse signal transmitted to the medium, at each of predetermined times; a phase connection step of performing phase connection processing, at each of the predetermined times, on the phase change at each of the points calculated in the calculation step; and a correction step of detecting an outlier using a phase change at each of the points at the same time at which the phase connection processing is performed in the phase connection step, and correcting the outlier, at each of the predetermined times.
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公开(公告)号：US20240295433A1
公开(公告)日：2024-09-05
申请号：US18551642
申请日：2021-03-23
Applicant: Nippon Telegraph and Telephone Corporation
Inventor： Yoshifumi WAKISAKA , Tatsuya OKAMOTO , Daisuke IIDA , Yusuke KOSHIKIYA , Masashi KIKUCHI , Nazuki HONDA
CPC classification number: G01H9/004 , G01M11/3109 , G01D5/35358
Abstract: A signal processing method executed by a signal processing device, includes performing a phase connection process on a position in a space and a phase value at each of a plurality of times, performing outlier correction of a phase value for each position in the space in a predetermined direction of the space at a predetermined time among the plurality of times based on a result of the phase connection process, and correcting a phase value at a time other than the predetermined time for each of correction target positions among positions in the space.
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公开(公告)号：US20240280403A1
公开(公告)日：2024-08-22
申请号：US18567606
申请日：2021-06-09
Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Inventor： Yoshifumi WAKISAKA , Daisuke IIDA , Yusuke KOSHIKIYA , Hiroyuki IIDA , Nazuki HONDA
CPC classification number: G01H9/004 , G01D5/35358
Abstract: The present disclosure relates to a vibration measuring instrument that repeatedly injects a plurality of light pulses with different optical frequencies into an optical fiber, and performs distributed acoustic sensing-phase (DAS-P). In the vibration measuring instrument, light pulses having a waveform with a spectral side lobe smaller than a side lobe of a rectangular wave are used as the plurality of light pulses.
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