Hitachi, Ltd.

Hitachi Communication Technologies, Ltd.

Other

Yasuyuki Fukashiro

Hideaki Tsushima

Tooru Hirai

Shigeki Kitajima

Yukio Hayashi

Sunao Kakizaki

Tetsuya Uda

Hiroyuki Nakano

Takashi Mori

Koji Takatori

Masahiro Takatori

Hirohisa Sano

Tatsuo Kanetake

Shoichi Hanatani

Hidemasa Narita

Hiroshi Takeuchi

Kohei Mandai

Shinichi Kuwano

Masafumi Kamakura

Kenji Yamahara

Yasuhiro Uchiyama

Eita Miyasaka

Yoshio Nogi

Hideaki Tushima

Sigeki Kitajima

Tomohiro Mori

It is provided an optical receiver comprising a compensator, a compensation controller and a clock extractor. The optical receiver selects first and second values, and obtains a stabilization time necessary to change the dispersion value and a transition time shorter than the stabilization time, compensates the received optical signal using the selected first value, changes the dispersion value from the first value into the second value, compensates the received optical signal using the dispersion value when the transition time has passed since starting to change the dispersion value, creates second extraction information of the dispersion value after the transition time, compensates for dispersion of the optical signal using an dispersion value calculated based on the second value and the difference between the dispersion value after the transition time and the second value in a case where the created second extraction information indicates that the clock extraction is available.

Optical receiver and optical transfer apparatus

In an embodiment of the invention, an optical transport apparatus comprises first wavelength-division-multiplex optical signal processing units each corresponding to each of transmission lines, an interface unit connected to a client apparatus and converting a client signal to and from a signal to be wavelength-division multiplexed, and a second wavelength-division-multiplex optical signal processing unit connected to the interface unit and receiving the signal to be wavelength-division multiplexed from the interface unit. Each of the first wavelength-division-multiplex optical signal processing units includes a wavelength selective switch including inputs, multiplexing signals selected from optical input signals received from the inputs and outputting the multiplex signal to a corresponding transmission line. The second wavelength-division-multiplex optical signal processing unit includes an optical splitter splitting an optical signal including the signal to be wavelength-division multiplexed and outputting the split signals to the wavelength selective switches in the first wavelength-division-multiplex optical signal processing units.

Optical transport apparatus and optical transport system

A transmission system is provided in a synchronous network, for establishing synchronization with a degree of precision and at a speed being comparable levels as a conventional technique, and further decreasing the probability of out-of-synchronization occurrence. In the present invention, a synchronization signal is detected without performing error correction until synchronization is established, and after the synchronization is established, it is monitored whether or not out-of-synchronization occurs, according to the synchronization signal that has been subjected to the error correction.

Sending apparatus, receiving apparatus, and transmission system

There arises a problem that power consumption increases along with an increasing throughout of an FEC function effective in speeding up of a transmission speed. FEC function information necessary for a system is prepared, and multiple FEC functions are properly used according to a selected transmission line, etc.

Optical communication card and optical transmission device

Multiplexing-technology based large-capacity transmission requires the installation of many types of interface card. In addition, supporting a redundant configuration for preventing data communication from being interrupted requires the devices and cards more than double those required for the production system. An optical communication card includes multiple optical signal transmission/reception units, main signal processing units corresponding to the optical signal transmission/reception units and required for a multiplexed system, and a connection selection unit that can switch among multiple optical transmission lines, and each of the main signal processing units includes multiple function units and a function selection unit.

Optical communication card and communication device

The present invention relates to an optical cross-connect apparatus supporting plural directions, and provides a method of effectively performing an alarm indication by a node supervisory unit of the optical cross-connect apparatus. The node supervisory unit includes an alarm indication information storage unit that manages a management table for each of the plural directions. The management table manages not only received alarm indication information but also 'internal WSS input/output port optical fiber connection state', 'WSS optical path setting state on DROP/THROUGH selection side', &#x201c;transponder destination location&#x201d;, and &#x201c;destination direction&#x201d;, with respect to each direction. Then, a process flow is added to match received FDI information with the management information stored in the management table for each direction, and to specify an alarm destination.

Optical cross-connect apparatus

Where an integrated monitoring and controlling unit is to control an optical add-drop unit so as to cause transmit signals from the optical transceiver of a first optical node to be received by the optical transceivers of plural different optical nodes, this purpose can be achieved by an optical transmission system provided with an alarm inhibiting device that can inhibit the optical transceiver, which is a source of transmission, from issuing any unexpected alarm.

Optical transmission system and optical node

There is provided an optical signal transmission apparatus having a stable dispersion compensation function without unnecessarily controlling a compensation value even when a main signal quality is deteriorated due to a factor other than dispersion or in the case of a transmission failure. When it is determined that a signal quality is deteriorated due to dispersion of a fiber by determining a control mode of a variable dispersion compensator by means of optical noise information and received power information in addition to bit error information of a received signal, a compensation value of the variable dispersion compensator is varied and a compensation value other than the dispersion of the optical fiber is held to an existing set value.

Optical signal transmission apparatus

An optical switch is constructed by: first and second optical switches each having ports of k inputs and k outputs; a third optical switch of k inputs and k outputs which can perform a bi-directional transmission; 2k first optical circulators; 2k second optical circulators; and 2k selecting switches. First to kth interfaces are connected by the first optical switch. (k+1)th to 2kth interfaces are connected by the second optical switch. The first to kth interfaces are connected to one of the (k+1)th to 2kth interfaces by the third optical switch. An optical crossconnect apparatus is also provided.

Optical switch and optical crossconnect apparatus

Normality of links on a spare path or the links and nodes is monitored. When the spare path cannot be used, at least any one of nodes at both ends in a segmented path section is changed to another node on a working path. The segmented path section is changed to set another spare path. When a fault monitoring section which can accumulatively detect abnormal information is changed to the changed partial working path section, alarm generation in the fault monitoring section is prevented to release the prevention after completion of the change.

Optical, network, node apparatus and method for recovery path fault

A method is provided for detecting an optical reflection position in an optical switching unit by using a measuring system. Multiple switching commands are provided in order to direct a test light to an input port and an output port of the optical switching unit. Status information regarding the internal path of the test light is stored in a memory, along with flags corresponding to the magnitude of reflected light generated when the test light is reflected from an abnormal position along the internal path selected. The status information is stored in the form of a reflection alarm information table where the flags are stored in association with each of the internal paths. A rearmost connection among the optical interconnections in the optical switching unit is detected as an abnormal position based on the reflection alarm information table and the interconnection control table.

Optical switching apparatus with optical reflection monitor and reflection monitoring system

An optical transmission apparatus includes optical transmitters for transmitting optical signals and first monitor units for monitoring optical signals from the optical transmitters. A multiplexer is provided for multiplexing the optical signals from the optical transmitters into a multiplexed signal. A second monitor unit is provided for monitoring each optical signal which is multiplexed in the multiplexed signal from the multiplexer. A processing unit is provided for comparing a first number of optical signals detected by the first monitor units and a second number of optical signals detected by the second monitor unit.

Wavelength-division multiplexing optical transmitter

Disclosed is an optical cross connect apparatus that is applicable to an end office node and relay node in a path. The optical cross connect apparatus includes an optical switch for generating plural optical output signals from plural optical input signals; an optical level monitor section for detecting the optical levels of the optical input signals; and a control section that is connected to the optical switch and the optical level monitor section, includes a path switching management section for retaining a path switching management table, references the path switching management table when the optical input signals detected by the optical level monitor section are found to be OFF, and judges whether the optical switch should be operated.

Optical cross connect apparatus and optical transmission system

In working path setting, a backup path is previously prepared assuming a link failure, and a demultiplexer of a bypass link is connected to a wavelength conversion repeater through an optical switch. Upon occurrence of a link failure, the wavelength conversion repeater is connected to a multiplexer of the bypass link by means of the optical switch to forward an in-channel control signal to the wavelength conversion repeater of an adjacent node where the in-channel control signal is sequentially forwarded to reserve a backup bandwidth. Then, output wavelengths and targets are exchanged between a wavelength tunable transponder and the wavelength tunable repeater.

Optical crossconnect apparatus

An optical switch having plural input terminals and plural output terminal, plural dispersion compensators, and a controller for monitoring the change-over state of the optical switch and the dispersion compensation quantities of the plural dispersion compensators and controlling the setting of the optical switch are provided. In response to a request for setting dispersion compensation, the optical switch is set according to the dispersion compensation quantity of each dispersion compensator and the change-over state of the optical switch.

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Yokohama, Japan

Yasuyuki Fukashiro