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

IPC: G01H9/00 ,  G01D5/353

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.

公开(公告)号：US20250110018A1

公开(公告)日：2025-04-03

申请号：US18833299

申请日：2022-02-14

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Atsushi NAKAMURA ,  Yusuke KOSHIKIYA

IPC: G01M11/00

Abstract: An object of the present invention is to provide an optical fiber testing apparatus and an optical fiber testing method capable of measuring distance dependency of inter-core crosstalk of a non-coupled multicore fiber at the time of the bidirectional transmission.
An optical fiber testing apparatus (301) according to the present invention includes a measurement device (10) which inputs an optical pulse from one end (A) of a non-coupled multicore fiber (50) to one core of the non-coupled multicore fiber (50), and measures a first light intensity of backscattered light output from the one core at one end (A), and inputs a light pulse from one end (A) of the non-coupled multi-core fiber (50) to another core, and measures a second light intensity of the backscattered light output from the one core at one end (A); and a calculator (20) which calculates, from the first light intensity and the second light intensity, inter-core crosstalk distance dependency when bidirectional transmission is performed.

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：US20240426703A1

公开(公告)日：2024-12-26

申请号：US18707958

申请日：2021-11-11

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Atsushi NAKAMURA ,  Tomokazu ODA ,  Yusuke KOSHIKIYA

IPC: G01M11/00

Abstract: An object of the present invention is to provide an optical transmission line test apparatus and a test method capable of measuring a cumulative crosstalk of an optical transmission line in which a plurality of uncoupled multi-core fibers are connected in series from one end side with an OTDR.
An optical transmission line test apparatus 301 according to the present invention measures a cumulative crosstalk of an optical transmission line 50 in which a plurality of uncoupled multi-core fibers 50-i are connected in series. The optical transmission line test apparatus 301 includes a test light input unit 10 that inputs optical pulses to each of cores of the uncoupled multi-core fiber 50-1 at one end 50a of the optical transmission line 50; a reception unit 20 that receives backscattered light for each of the cores output from one end 50a; and a calculation unit 30 that acquires a loss distribution occurring in each of the cores from the backscattered light, and calculates the cumulative crosstalk from a connection loss at a connection point zj of the uncoupled multi-core fiber obtained from the loss distribution and a known inter-core mode coupling of each of the uncoupled multi-core fibers 50-i.

公开(公告)号：US20240344928A1

公开(公告)日：2024-10-17

申请号：US18580408

申请日：2021-08-02

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Atsushi NAKAMURA ,  Yusuke KOSHIKIYA ,  Nazuki HONDA

IPC: G01M11/00

CPC classification number: G01M11/331 ,  G01M11/333

Abstract: A device according to the present disclosure: acquires a group delay time difference between eigenmodes, at a specific wavelength, in a coupled two-core fiber; acquires spatial mode dispersion between the eigenmodes, at the specific wavelength, in the coupled two-core fiber; and calculates an average power coupling coefficient between cores, at the specific wavelength, within an entire length of the coupled two-core fiber by using the group delay time difference, the spatial mode dispersion, and a length of the coupled two-core fiber.

公开(公告)号：US20240264034A1

公开(公告)日：2024-08-08

申请号：US18289755

申请日：2021-06-04

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Tomokazu ODA ,  Atsushi NAKAMURA ,  Yusuke KOSHIKIYA ,  Nazuki HONDA

IPC: G01M11/02

CPC classification number: G01M11/02

Abstract: An object is to provide an optical fiber test method and an optical fiber test device capable of acquiring a maximum loss of a higher-order mode at a connection point of an optical fiber transmission line through which a plurality of modes propagate.
The optical fiber test device according to the present invention includes: a light source unit 10 that allows probe light L1, which has a tunable wavelength and is continuous light, to enter one end T1 of an optical fiber in a fundamental mode and allows pulsed pump light L2, which is shifted to a high frequency side by a frequency at which a Brillouin interaction occurs with respect to the probe light L1, to enter the other end T2 of the optical fiber in a higher-order mode as a measurement target; and an analysis unit 20 that acquires, from a light intensity of the probe light L3 amplified by the pump light L2, a time waveform of an amplification component, calculates a connection loss of the pump light L2 at a connection point from a ratio of the amplification components before and after the connection point, acquires a wavelength dependency of the connection loss, detects a maximum value of the connection loss from the wavelength dependency of the connection loss, and sets the maximum value as a maximum loss of the higher-order mode at the connection point.

公开(公告)号：US20230332980A1

公开(公告)日：2023-10-19

申请号：US18026856

申请日：2020-10-07

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Tomokazu ODA ,  Atsushi NAKAMURA ,  Daisuke IIDA ,  Yusuke KOSHIKIYA ,  Nazuki HONDA

IPC: G01M11/02

CPC classification number: G01M11/02

Abstract: An object of the present invention is to provide an optical fiber measurement system, an optical fiber measurement method, a control calculation device, and a program that are capable of measuring loss and XT occurring at a plurality of points of an optical fiber in which a plurality of modes propagate, for each point. An optical fiber measurement system according to the present invention includes a light incident circuit which makes a probe light incident on one end of an optical fiber and makes a secondary probe light and a pump light as an optical pulse incident on the other end of the optical fiber; a light receiver which measures a light intensity of arbitrary one propagation mode in the probe light propagating through the optical fiber; and a control calculation device which sets a propagation mode of the probe light, the secondary probe light, and the pump light, an optical frequency difference of the secondary probe light, and an optical frequency difference of the pump light with respect to the light incident circuit, and calculates loss and crosstalk at each point in a longitudinal direction of the optical fiber to be measured connected as the optical fiber, from the light intensity measured by the light receiver.

公开(公告)号：US20210003474A1

公开(公告)日：2021-01-07

申请号：US16977882

申请日：2019-03-05

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Yusuke KOSHIKIYA ,  Atsushi NAKAMURA ,  Kazutaka NOTO ,  Tetsuya MANABE

IPC: G01M11/00

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.

公开(公告)号：US20250123415A1

公开(公告)日：2025-04-17

申请号：US18682522

申请日：2021-08-16

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Tatsuya OKAMOTO ,  Daisuke IIDA ,  Yusuke KOSHIKIYA ,  Nazuki HONDA

IPC: G01V1/01 ,  G01H9/00 ,  G01V1/22

Abstract: The present disclosure provides an underground facility position contrast system S, which includes: a scattered light intensity distribution measurement device 1 for measuring, when an earthquake vibration is applied to an optical fiber F laid underground, a change over time in a scattered light intensity distribution in a longitudinal direction of the optical fiber F; and an underground facility position contrast device 2 for measuring a change over time in a distortion response distribution in the longitudinal direction of the optical fiber F based on the change over time in the scattered light intensity distribution in the longitudinal direction of the optical fiber F, estimating an underground facility state of the optical fiber F based on the change over time in the distortion response distribution in the longitudinal direction of the optical fiber F, and associating the underground facility position of the optical fiber F with a longitudinal distance of the optical fiber F.

公开(公告)号：US20250060245A1

公开(公告)日：2025-02-20

申请号：US18722505

申请日：2022-10-14

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Masaaki INOUE ,  Yusuke KOSHIKIYA

IPC: G01H9/00

Abstract: A determination device 301 is a determination device that categorizes an installation environment of an optical cable 21, and includes a feature extraction unit 212 that extracts a feature vector at each position of the optical cable 21 from a vibration distribution in a longitudinal direction of the optical cable 21, a calculation unit 219 that calculates a discriminant function at each position of the optical cable 21 from the feature vector and a weight vector corresponding to the installation environment, in need of categorization, of the optical cable 21, and a determination unit 220 that compares the discriminant function with teacher signals representing two states and designates a state of the nearer of the teacher signals as a state of the optical cable 21, at each position of the optical cable 21.