Nippon Telegraph and Telephone Corporation

Ntt Corporation

Hiroyuki Oshida

Daisuke Iida

Atsushi Nakamura

Keiji Okamoto

Yoshifumi Wakisaka

Tatsuya Okamoto

Nazuki Honda

Tomokazu Oda

Yukihiro Goto

Masaaki Inoue

Ryuji Honda

Tomoya Shimizu

Hitoshi Niigaki

Atsushi Sagata

Shingo Ando

Yasuhiro Yao

Kana Kurata

Shigehiro Matsuda

Toshiya Ohira

Kazutaka Noto

Tetsuya Manabe

Kunihiro Toge

Yuto Sagae

Shingo Ono

Junichi Kawataka

Masaki Waki

Chihiro Kito

Masaki Nakamori

An object of the present disclosure is to enable vibration analysis using a spectral shift under appropriate conditions depending on a measurement object. According to the present disclosure, there is provided a vibration distribution measuring apparatus which measures backscattered light in an optical fiber to be measured a plurality of times at different times, extracts an optical spectrum of a window section determined from a plurality of backscattered light waveforms obtained by the measurement, and measures a vibration distribution in the optical fiber to be measured using optical spectra of the plurality of extracted backscattered light waveforms, in which the optical spectrum of the window section is calculated using the window section in which the vibration amplitude in the window section in the optical fiber to be measured is larger than a threshold value defined in the window section.

Distributed acoustic sensing device and method

A vibration detection apparatus is presented which can avoid occurrence of a point where detection sensitivity deteriorates in vibration detection of a scattered light intensity monitor according to optical frequency multiplexing. A multi-dimensional space having as many dimensions as the number of frequencies to be used, causes scattered light intensity change at each optical frequency to correspond to each axis, plots a scattered light signal as a vector on the space, performs linear approximation passing through an origin on the space having a plurality of plotted vector points as original data, and performs vibration detection using a direction vector of an approximate straight line obtained as a result of the approximation.

Vibration detection device and vibration detection method

An object of the present disclosure is to provide a power coupling coefficient measurement method and a power coupling coefficient measurement device capable of inexpensively and easily measuring a power coupling coefficient. The power coupling coefficient measurement method according to the present disclosure is a power coupling coefficient measurement method for measuring a power coupling coefficient of a multi-core fiber in order to achieve the aforementioned object, and includes: inputting a test light pulse from one end of the multi-core fiber to any one of cores; receiving backscattered light of the core to which the test light pulse is input or any one of the other cores; measuring an intensity distribution of the backscattered light with respect to a distance from the one end of the multi-core fiber; and calculating the power coupling coefficient from the intensity distribution of the backscattered light.

Power coupling coefficient measuring method and power coupling coefficient measuring device

A phase measurement method is presented which causes wavelength-multiplexed pulsed light to be incident on a measurement target optical fiber, produces a scattered light vector obtained by plotting scattered light from the measurement target optical fiber for each wavelength onto a two-dimensional plane having the in-phase component thereof on the horizontal axis and the orthogonal component thereof on the vertical axis, rotates the produced scattered light vector for each wavelength at each place in the measurement target optical fiber to align the directions of the vectors, generates a new vector by calculating the arithmetic average of the vectors having the aligned directions, and calculates the phase by using the values of the in-phase and orthogonal components of the generated new vector.

Phase measuring method and signal processing device

An object of the present disclosure is to provide a few-mode fiber testing method and a few-mode fiber testing device capable of acquiring a loss and inter-mode crosstalk for each mode at a connection point of a few-mode fiber by measurement only from one end of FUT. The few-mode fiber testing method according to the present disclosure includes receiving a test light pulse in a basic mode from one end of an optical fiber under test that is connected in series with few-mode fibers of the same type, measuring an intensity distribution relating to a distance from the one end of backward Brillouin scattering light generated by receiving a test light pulse, obtaining a transmittance of the backward Brillouin scattering light at a connection point of the optical fiber under test from the measured intensity distribution, and calculating a connection loss of the basic mode from the transmittance, calculating a ratio of an axial deviation amount to a mode field radius of the optical fiber under test at the connection point from the calculated connection loss, and calculating a connection loss of a higher-order mode and inter-mode crosstalk between different modes from the calculated ratio.

Several mode fiber test method and several mode fiber test device

An object of the present invention is to propose a design method of a minimum value N of the number of multiplexed frequencies that is necessary for measuring an object vibrational frequency according to DAS-P while taking into consideration a trade-off between a measurement distance and an upper limit of a measurable vibrational frequency. When a phase change of an arbitrary section of a measured optical fiber is represented by A×sin(2πfvt), N=4Zfv/ν is satisfied when A is smaller than π/2 but N=2Zfv/(ν·Arcsin (π/2A)) is satisfied when A is equal to or larger than π/2, where fv represents vibrational frequency, t represents time, Z represents a length of the measured optical fiber (a measurement distance), and ν represents the speed of light inside the measured optical fiber.

Optical pulse test method and optical pulse test equipment

An object of the present invention is to provide an immersion detection system and an immersion detection method capable of eliminating module replacement in the occurrence of immersion and simplifying system management. An immersion detection system according to the present invention includes: an immersion detection sensor having two optical fibers connected in series such that end faces of the two optical fibers abut on each other with a predetermined gap; an optical measurer that causes test light with a plurality of wavelengths to enter an optical transmission line having a plurality of the immersion detection sensors connected in series with optical fibers and measures a return loss of the test light at the immersion detection sensor for each of the wavelengths and for each of the immersion detection sensors; and a determiner that averages, for each of the immersion detection sensors, the return losses for the wavelengths and performs threshold determination on the presence or absence of immersion.

Inundation detection system and inundation detection method

An object of the present invention is to provide an information processing apparatus, an information processing method, and a program, which are capable of determining an owner of an attachment attached to a facility using a solid model of a facility extracted from three-dimensional point group data. The present invention determines the owner of the attachment from a planar positional relationship between the solid model of a columnar structure and the solid model of the attachment in the solid model. For example, a distance between a utility pole and a center of a point (a center of a ground boundary) at which a branch line or a post reaches a ground is acquired, and whether the branch line or the post is owned by a communication company or an electric power company is determined based on whether the distance exists in a constant threshold determined by the communication company or the electric power company.

Information processing equipment, information processing methods, and programs

An object permittivity measurement apparatus according to the present disclosure includes: a light wave distance measurement device configured to measure reciprocating time t of a light wave with which an object is irradiated and that is reflected and returned from the object, and calculate a distance L to the object using the following equation (1),/2  (1)

Permittivity measuring device and thickness measuring device

Provided is a point cloud analysis device that curbs a decrease in model estimation accuracy due to a laser measurement point cloud. A clustering unit () clusters a point cloud representing a three-dimensional point on an object obtained by a measurement unit mounted on a moving body and performing measurement while scanning a measurement position, within a scan line, to obtain a point cloud cluster. A central axis direction estimation unit () estimates a central axis direction based on the point cloud cluster. A direction-dependent local effective length estimation unit () estimates a local effective length based on an estimated central axis direction and an interval of scan lines, the local effective length being a length when a length of projection of the point cloud cluster in a central axis direction for each of the point cloud clusters is interpolated by an amount of a loss part of the point cloud.

Point cloud analysis device, method, and program

It is an object of the present invention to provide an aerial optical fiber cable inspection method, an aerial optical fiber cable inspection device, and a program which can identify a cable sagging section from vibration sensing results. In the aerial optical fiber cable inspection method according to the present invention, a vibration distribution waveform along the longitudinal direction of an aerial optical fiber cable measured using an optical fiber vibration sensing device is received as an input, a standard deviation of the amplitude of vibration at each position in the vibration distribution waveform is calculated, and a section with a standard deviation larger than that of other sections is identified as a cable sagging section.

Aerial optical fiber cable inspection method, aerial optical fiber cable inspection device, and program

An object of the present invention is to provide an optical fiber test method, an optical fiber test apparatus, and a program, capable of detecting a boundary of an optical fiber line facility regardless of a change in a noise amount. A change amount (a differential value) of an OTDR waveform increases toward a distal end due to noise effects, making it difficult to determine a boundary of the optical fiber using the change amount. Therefore, in the present invention, a dispersion of the OTDR waveform, which increases toward a distal end due to noise effects, is also used to determine the boundary of the optical fiber. In other words, in the present invention, the noise amount is expressed by the dispersion, and the dispersion is compared with the change amount such as a differential value as a threshold, to determine the boundary of the optical fiber. For this reason, when noise increases, the threshold increases together with an increase in the change amount, and therefore, the boundary of the optical fiber can be determined regardless of noise.

Fiber optic test methods, fiber optic test equipment, and programs

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 Ndue to frequency modulation caused by dynamic strain. An index of tolerance of vibration distribution measurement to the delay deviation Nis also clarified.

Distributed vibration measuring device and method

An object of the present invention is to provide a Brillouin optical sensing device and an optical sensing method capable of reducing introduction costs. The Brillouin optical sensing device according to the present invention includes: a sensing fiberin which a plurality of optical fibers having Brillouin frequency shift characteristics different from each other are arranged in parallel; an optical measuring instrumentthat launches an optical pulse into at least two of the optical fibers of the sensing fiberto generate Brillouin scattering lights and measures a beat frequency of a beat signal between the Brillouin scattering lights at any position of the sensing fiber; and an arithmetic processing unitthat acquires a physical quantity of the sensing fiberat said any position based on the beat frequency acquired by the optical measuring instrument

Brillouin optical sensing device and optical sensing method

A structure detection device according to an embodiment includes: a reading processing unit that reads, as three-dimensional point group data on an object present in a three-dimensional space, data including three-dimensional position information and color information at a point on a surface of the object; a filtering processing unit that performs filtering processing for extracting three-dimensional point group data on a detection-target structure from the three-dimensional point group data on the object present in the three-dimensional space based on the color information; and a generation processing unit that generates three-dimensional model data in which the detection-target structure is represented as a three-dimensional model based on the three-dimensional point group data on the detection-target structure, the three-dimensional point group data being extracted by the filtering processing unit.

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Musashino, Japan

Hiroyuki Oshida