Hitachi, Ltd.

Hitachi Communication Technologies, Ltd.

Kenta Noda

Hiroyuki Nakano

Tetsuya Uda

Yasuhiro Uchiyama

Hiroshi Masuda

Takuya Iwasawa

Takayuki Suzuki

A transponder for performing bidirectional conversion between a client-side signal used for communication to a client device and a transmission path-side signal used for communication to a transmission path, the transponder comprising: a client-side interface for inputting/outputting the client-side signal; a transmission path-side interface for inputting/outputting the transmission path-side signal; a connection determining unit for determining which of the another client-side interface and the client device is coupled to the client-side interface; and a transmission signal generating unit for outputting, in a case where a state signal indicating a state on a transmission path side is input to the transmission path-side interface, a transmission signal indicating that the state signal has been input, from the client-side interface, wherein: the transmission signal generating unit changes a form of the transmission signal to be output from the client-side interface, based on a determination result obtained by the connection determining unit.

Transponder, repeater, and terminal equipment

An embodiment of the invention is an optical communication system including: a plurality of interface boards which transmit and receive optical signals to and from interface boards facing the plurality of interface boards; and a monitoring control device which monitors states of the plurality of interface boards. A first interface board of the plurality of interface boards includes: a replacement unit capable of monitoring the states of the plurality of interface boards on behalf of the monitoring control device and independently receiving supply of power; and a control unit configured to start the replacement unit in a case where a fault occurs in the monitoring control device and stop or halt the replacement unit in a case where there is no fault in the monitoring control device.

Optical communication system, interface board and control method performed in interface board

Provided is an optical relay system () which is capable of suppressing wasteful power consumption of an entire system to a low level. The optical relay system () includes a plurality of relay devices () and a network control device (). The network control device () causes an optical signal to be regenerated by a regenerative repeater () within the relay device () existing at an upstream of the relay device () reporting that the optical signal has deteriorated by a degree exceeding a predetermined level. Further, the network control device () causes the regenerative repeater () to stop regenerating the signal in a case where deterioration of the signal remains within an allowable range even when the regenerative repeater () stops regenerating the signal.

Optical relay system and network control device

An optical transmission apparatus comprising a first detector for detecting the power of the supervisory signal light separated from received wavelength-division multiplexed signal lights; a second detector for detecting the power of the wavelength-division multiplexed signal lights after the separation of the supervisory signal light; a gain-controlled type optical amplifier for amplifying the wavelength-division multiplexed signal lights; an optical attenuator coupled to the amplifier; and a control unit for controlling the optical amplifier and the optical attenuator so as to keep the output level of the wavelength-division multiplexed signal lights to a predetermined target value, wherein the control unit restrains automatic output level control by the optical attenuator when the supervisory signal light power fluctuates within its permissible range and fluctuations in the signal light power have deviated from its permissible range.

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Yokohama, Japan

Kenta Noda