Hitachi, Ltd.

Koji Takatori

Yasuyuki Fukashiro

Hidemasa Narita

Hiroshi Takeuchi

Tetsuya Uda

Kohei Mandai

Masafumi Kamakura

Hideaki Tsushima

Eita Miyasaka

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

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

A simple synchronizing detection circuit is provided in each of logical operation circuits, and a method for making a synchronizing detection in parallel is adopted. A selector control section monitors the states of the simple synchronizing detection circuits in parallel, and supplies an output from a proper logical operation circuit detecting the synchronization establishment to a frame synchronizing/terminating circuit at the latter stage. There is provided a function of relieving a synchronization determination condition if the synchronization establishment is not detected in any of the synchronizing detection circuits, whereby the output from the proper logical operation circuit can be selected depending on a load on a transmission path.

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Tokyo, Japan

Koji Takatori