Abstract: A clock supply device includes a receiving unit configured to receive frame synchronization packets from an asynchronous network and generate timing signals; a phase comparing unit configured to perform phase comparison by comparing phases of the timing signals generated by the receiving unit and clock signals generated by an internal oscillating unit; a phase variation detection unit configured to detect a frequency variation of the frame synchronization packets based on a trend of a variation amount of a phase difference that is obtained by performing a statistical process on count values obtained as a result of the phase comparison; and an oscillating frequency control unit configured to control an oscillating frequency of the internal oscillating unit when the phase variation detection unit detects the frequency variation of the frame synchronization packets.

Abstract: A clock supply device includes a receiving unit configured to receive frame synchronization packets from an asynchronous network and generate timing signals; a phase comparing unit configured to perform phase comparison by comparing phases of the timing signals generated by the receiving unit and clock signals generated by an internal oscillating unit; a phase variation detection unit configured to detect a frequency variation of the frame synchronization packets based on a trend of a variation amount of a phase difference that is obtained by performing a statistical process on count values obtained as a result of the phase comparison; and an oscillating frequency control unit configured to control an oscillating frequency of the internal oscillating unit when the phase variation detection unit detects the frequency variation of the frame synchronization packets.

Abstract: A redundant changeover apparatus causing no frame synchronization loss even upon occurrence of changeover between working system and protection system. In case of an in-apparatus synchronization system, when two input signals which are mutually asynchronous in phase are changed over by a changeover switch, a changeover switch, a clock extractor, a PLL circuit, and a clock changing portion transmit signals with clocks before the changeover being gradually changed to clocks after the changeover. Alternatively, in case of an in-apparatus synchronize system, data are separated from clocks so that the data are once changed to data with reference clocks, and then for the data, clocks before the changeover are gradually changed to clocks after the changeover.

Abstract: In a long-distance and large-capacity optical transmission system, a dispersion compensating device showing a wavelength-dependency of dispersion characteristic is provided in a transmission line which makes a connection between a transmission terminal node and a reception terminal node. The reception terminal node acquires a dispersion quantity relative to single-wavelength light outputted from a wavelength-variable transmitter which is provided in the transmission terminal node for outputting single-wavelength light, and transmits wavelength control information corresponding to the acquired dispersion quantity to the transmission terminal node. The transmission terminal node varies the wavelength of the transmitter on the basis of the transmitted wavelength control information. This enables acquiring an optimum dispersion compensation quantity with a simple configuration and optimizing a dispersion compensation quantity for each channel at the transmission of wavelength-multiplexed light.

Abstract: A redundant changeover apparatus causing no frame synchronization loss even upon occurrence of changeover between working system and protection system. In case of an in-apparatus synchronization system, when two input signals which are mutually asynchronous in phase are changed over by a changeover switch, a changeover switch, a clock extractor, a PLL circuit, and a clock changing portion transmit signals with clocks before the changeover being gradually changed to clocks after the changeover. Alternatively, in case of an in-apparatus synchronize system, data are separated from clocks so that the data are once changed to data with reference clocks, and then for the data, clocks before the changeover are gradually changed to clocks after the changeover.