Nec Corporation

Koji Asahi

Yoshiaki Aono

Yukihide Yoda

Sadao Fujita

A monitoring system according to the present disclosure includes an optical fiber () laid in a monitoring area; an authenticating unit () configured to authenticate a person or a vehicle passing through a gate (G) for entering the monitoring area; an optical fiber sensing unit () configured to acquire, based on an optical signal received from the optical fiber (), a parameter having a unique pattern corresponding to the pattern of action of the authenticated person or vehicle; and an analyzing unit () configured to identify the pattern of action of the authenticated person or vehicle based on the unique pattern of the parameter.

Monitoring system, monitoring device, monitoring method, and non-transitory computer-readable medium

A monitoring system according to the present disclosure includes an optical fiber () laid on a ground or a seabed, an optical fiber sensing unit () configured to receive an optical signal from the optical fiber () and detect a vibration produced in the ground or the seabed based on the optical signal, and an analyzing unit () configured to identify a natural phenomenon that has caused the detected vibration based on a unique pattern of the detected vibration.

A utility pole deterioration detection system includes a cable () disposed in a utility pole (), the cable () containing a communication optical fiber, a receiving unit () configured to receive an optical signal containing a pattern that changes according to a deterioration state of the utility pole () from at least one optical fiber contained in the cable (), and a detection unit () configured to detect a deterioration state of the utility pole () based on the pattern.

Utility pole deterioration detection system, utility pole deterioration detection apparatus, utility pole deterioration detection method, and non-transitory computer readable medium

A utility pole location specifying system according to the present disclosure includes a cable () containing a communication optical fiber disposed in a utility pole (), a receiving unit () configured to receive an optical signal containing a characteristic pattern of the utility pole () from at least one communication optical fiber contained in the cable (), and a specifying unit () configured to specify a location of the utility pole () based on the characteristic pattern.

Utility pole location specifying system, utility pole location specifying apparatus, utility pole location specifying method, and non-transitory computer readable medium

A state specifying system according to the present disclosure includes a cable () disposed in a utility pole (), the cable () containing a communication optical fiber, a receiving unit () configured to receive an optical signal from at least one optical fiber contained in the cable (), and a specifying unit () configured to specify a state of the utility pole () or an environmental state around the utility pole () corresponding to a pattern of the optical signal received by the receiving unit ().

State specifying system, state specifying apparatus, state specifying method, and non-transitory computer readable medium

An optical transmission system includes an optical fiber transmission line, one or more optical repeating apparatuses, an optical receiving apparatus, and a transferring route for transferring a supervisory signal based on a quality deterioration of an optical signal detected by the optical receiving apparatus to the optical repeating apparatus from the optical receiving apparatus. The optical repeating apparatus includes an optical level variation detecting unit for detecting a level variation of an optical signal and a level variation storing unit for storing information based on the level variation. The level variation storing unit sequentially discards a level variation information having passed a predetermined period while storing the level variation information in a constant interval, and holds storage of the level variation information from a time of storage of the level variation information based on a particular optical signal until a time controlled by the supervisory signal based on the particular optical signal transferred by the transferring route.

Optical transmission system, optical repeating apparatus, and quality supervising method

To provide an optical cross-connect apparatus capable of, even in the case where a light switch becomes large-sized, supervising quality and management information of light signals passing through inside the apparatus with low-cost configuration. For each of the light signals inputted from n pieces of input port, path setting in a branch connection state is performed in order following a control signal from a control section by connecting any one of n pieces of output port with a predetermined supervising port at n&times;m light SW. Quality and management information are detected from light signals outputted from a supervising output port at a light signal detecting section, and the quality and the management information are supervised at a light signal supervising section.

Optical cross-connect apparatus, and its signal monitoring method

An optical crossconnect selectively connects at least one input terminal with at least one output terminal. The optical crossconnect includes: an optical switch connecting at least one input port connected to the at least one input terminal with at least one output port connected to the at least one output terminal; at least one supervisory light generating circuit for sending a supervisory light from each of the at least one output port to the optical switch; and at least one supervisory light receiving circuit for receiving the supervisory light output from the at least one input port.

Optical crossconnect, optical network device, and connection status supervisory method

An optical transmission system capable of alleviating the non-linear optical effect from overhead portions of a bit pattern comprised of a plurality of bits, wherein a plurality of optical transmit devices input a clock signal of identical phase and frequency, and optical signals whose overhead positions are changed on each wavelength by respective variable delay lines under the control of a phase controller are sent to a transmit side WDM device. At the transmit side WDM device, these optical signals are multiplexed in a wavelength multiplexer and sent to the receive side WDM device. Receive side optical transmission devices receive the respectively isolated optical signals. A phase controller offsets the positions of the optical signals and sends them to the overhead on each wavelength so that the non-linear effect of the receive optical signal is suppressed and a satisfactory signal can be received.

Optical transmission system

Each node of an optical ring system having m nodes connected multiplexes wavelengths of &lgr;1 to &lgr;n in optical wavelength division and transmits signals. This optical ring system is composed of working optical fibers ( - and - ) and protection optical fibers ( - and - ). Each node is composed of 4&times;4 optical switches ( and ), a first optical preamplifier ( ), a first wavelength demultiplexer ( ), a first wavelength multiplexer ( ), a first optical booster amplifier ( ), a second optical preamplifier ( ), a second wavelength demultiplexer ( ), a second wavelength multiplexer ( ), a second optical booster amplifier ( ), a third optical preamplifier ( ), a third wavelength demultiplexer ( ), a third wavelength multiplexer ( ), a third optical booster amplifier ( ), a fourth optical preamplifier ( ), a fourth wavelength demultiplexer ( ), a fourth wavelength multiplexer ( ), a fourth optical booster amplifier ( ), and line terminals ( - to - ). In each node, 2&times;2 optical switches ( - to -n and - to -n) are connected in the working optical paths, and 2&times;2 optical switches ( - to -n and - to -n) are connected in the protection optical paths.

Node for optical communication and wavelength-division multiplexing transmission apparatus having a ring structure composed of the same nodes

An optical cross-connect has a plurality of input terminals to which photo signals are respectively inputted, a plurality of output terminals for respectively outputting the photo signals, and an optical switch for switching over an optical path between the input terminal and the output terminal. The optical switch, when switching over an optical path to a switchover target output terminal to which the optical path is newly connected from a pre-switchover output terminal through which the optical path is connected to the input terminal before the switchover, temporarily connects the optical path to both of the pre-switchover output terminal and the switchover target output terminal with a bridge connecting function. First and second monitor circuits for monitoring a state of the photo signal are disposed, respectively, between the input terminal and the optical switch, and between the optical switch and the output terminal. A connectivity of the optical switch is monitored from connectivity information, indicating the states of the photo signals before and after switching over the optical path, which is given from the monitor circuits. Prior to switchover of the optical path, the connectivity of the optical switch can be confirmed, and a reliability on the optical transmission system using the optical switch is thereby enhanced.

Optical cross-connect, method of switching over optical path, optical ADM, and optical cross-connect network system

A receiving apparatus includes a counter for counting for a prescribed period of time the number of bits having one of two different levels, out of bits forming a digital signal which is entered and having the two different levels, and supplying a count signal, a bit rate detector for calculating the bit rate of the digital signal from the count signal and supplying a multiplying factor selection signal, a differentiating circuit, into which the input digital signal is entered, for supplying a pulse signal at a varying point of the input digital signal, a rectifying circuit for accomplishing full-wave rectification of the pulse signal, and supplying a rectified pulse signal, a band-pass filter for passing harmonics of the clock component of the input digital signal contained in the rectified pulse signal, and a frequency dividing circuit, into which the harmonics are entered, for frequency-dividing the harmonics by a ratio set on the basis of the multiplying factor selection signal, and supplying a resultant frequency-divided clock signal.

Bit rate-selective type optical receiver, optical regenerative repeater and automatic bit rate discriminating method

A device comprises a plurality of nodes and four optical transmission lines of clockwise and counter-clockwise working operation lines and clockwise and counter-clockwise stand-by lines which connect the nodes in form of a ring. Each node is provided with first and second terminal sections including a receiver and transmitter, with a first optical path switch for switching the optical path between four output terminals of the counter-clockwise working operation and stand-by optical transmission lines, the second terminal section, and output terminal of a first stand-by line, and four input terminals of the clockwise operation and stand-by optical transmission lines, first terminal sections, and a second stand-by line. Each node is also provided with a second optical path switch for switching the optical path between four output terminals of clockwise operation and stand-by optical transmission lines, and first terminal section, and output terminal of the second stand-by path, and four input terminals of the counter-clockwise working operation and stand-by optical transmission lines, second terminal section, and input terminal of the first stand-by path.

Optical communication node and wavelength division multiplexing optical transmission device having ring structure comprising the optical communication nodes

A ring network is composed of an even-number of optical fibers wherein each pair of optical fibers forms a bidirectional transmission line and a plurality of nodes coupled through the optical fibers in ring topology. In this ring system, each of the nodes includes the even-number of Add/Drop circuits coupled to the optical fibers, respectively, and the even-number of optical transceivers each including an optical transmitter and an optical receiver. A switch changes a combination of an Add/Drop circuit and each of the optical transmitter and the optical receiver.

Optical WDM ring network

The n.times.n light matrix switch of the present invention comprises a n:1 optical coupler for wavelength-multiplexing the n input light signals having different wavelengths, a 1:n optical divider for dividing the wavelength-multiplexed light signals to n light signals, n wavelength tunable light band pass filter for extracting only an arbitrary one wavelength component out of n-divided light signals, and a controlling circuit for controlling the pass center frequency of the n wavelength tunable light band pass filter. The n wavelength tunable light band pass filters connected to the n output terminals supply all the n input light signal components which are wavelength-division-multiplexed. Thereby, any output terminal can select an arbitrary light signal out of n inputs quite independently from other output terminals. Further, there are n objects to be controlled which prescribes the connecting condition between input signal and output signal, this number is less than that of the conventional n.times.n light matrix switch. The n.times.n light matrix switch having the simple structure can provides excellent operability without blocking phenomenon.

Growing community of inventors

Tokyo, Japan

Koji Asahi