Fujitsu Corporation

Akio Morimoto

Michio Kusayanagi

Hiroyuki Kaneko

Hiroshi Nakaide

Noriaki Ohuchi

Takashi Nakajima

Takahiro Hosokawa

Makoto Takakuwa

Fumihiko Saito

Toshikazu Inoue

Yoshihiro Shimizu

Tooru Matsumoto

Hiroshi Yamasaki

Shoji Yoshida

Nobuo Iguchi

Koji Tatsumi

Satoshi Namura

Kazunori Kawabe

Tatsuru Iwaoka

Kazuhisa Shimazaki

Shinya Nakagaki

Kazuya Kumazaki

Mineharu Hattori

Tetsuji Ichikawa

Norihisa Uchimoto

Koichiro Yamada

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.

Clock supply device and transmission device

A first communication device receives an ATM cell bound for a second ATM device from a first ATM device via an ATM interface, and then the first communication device sends a data frame including the ATM cell to the second ATM device via wide area Ethernet. In addition, the first communication device sends a synchronization frame to the second ATM device via the wide area Ethernet continuously at a predetermined time interval in accordance with a clock frequency of the first ATM device. A second communication device receives the synchronization frame and measures a clock frequency of the first ATM device in accordance with a time interval of receiving the synchronization frame so as to reproduce a clock having the same frequency as the measured clock frequency. After that, the second communication device sends the clock to the second ATM device via an ATM interface.

System for supporting communications among ATM devices, device for supporting data transmission, method for sending data, and computer program product

A converter for connecting its ATM network with other ATM networks through a LAN, which is provided with an address translation table storing external VPIs, internal VPIs uniquely assigned to the LAN, and opposing MAC addresses for opposing converters in correspondence and a processing unit for performing control for transmitting, to the LAN, frames changed from the external VPI/VCIs of headers of cells from its ATM network to the internal VPI/VCIs by referring to the address translation table and having opposing MAC addresses corresponding to the internal VPI/VCIs attached, removing the opposing MAC addresses of frames received from the LAN by referring to the address translation table, and transmitting cells changed from internal VPI/VCIs to external VPI/VCIs to its ATM network.

Converter and communication control method

An optical transmission system includes an optical wavelength branching unit that shifts a wavelength transmission band in the short-wavelength or long-wavelength directions based on a branching filter operation temperature, and performs a branching operation on a wavelength-multiplexed signal. A reception transponder performs decoding on an error correction code. An error correction monitoring unit gathers an error correction amount upon which a branching filter temperature control unit sets the branching filter operation temperature. A transmission transponder performs encoding on an error correction code. An optical wavelength combining unit shifts the wavelength transmission band in the opposite direction from the shifting direction based on a combining filter operation temperature, to perform a combining operation on optical signals and output a wavelength-multiplexed optical signal. A combining filter temperature control unit sets the combining filter operation temperature based on the error correction amount sent from the optical reception device.

Optical transmission system

A failure detection system detects a failure of a package in a redundant system having a duplex package configuration. The failure detection system includes a first package including a signal processor for carrying out a predetermined signal processing on an input signal to the first package, where the first package is provided in each of first and second systems, a second package including a selector for selectively outputting an output signal of the signal processor of the first package in one of the first and second systems in response to a control signal, a failure detector for detecting a failure in the output signal of the signal processor of the first package in each of the first and second systems and for outputting a failure detection signal if the failure is detected, and a signal processor for carrying out a predetermined signal processing on the output signal of the selector, where the second package is provided in each of first and second systems, and a controller for supplying the control signal to the selector of the second package in each of the first and second systems based on the failure detection signal received from the second package in each of the first and second systems, so that the selector selectively outputs the output signal of the signal processor of the first package in an active one of the first and second systems. The controller includes a mechanism for disregarding the failure detection signal received from the second package during a predetermined time in response to a predetermined signal. This predetermined signal may indicate which one of the first and second systems is active or, indicate whether or not the second package of each of the first and second systems is mounted on a unit to which the first package of each of the first and second systems is mounted.

Signal processing apparatus including redundant first and second system

A multi-port time switch element for cross-connecting an n-channel multiplexed data includes m input ports for receiving m n-channel multiplexed data, a memory part for alternately writing and reading the n-channel multiplexed data, m selectors for writing and reading the n-channel multiplexed data so that each of the m selectors receives m.times.n data read from the memory part and selects one of the m.times.n data n times in an arbitrary sequence to output an n-channel multiplexed data, and m output ports for outputting the m n-channel multiplexed data read from the m selectors.

Multi-port time switch element

A clock distribution system includes a clock generation and distribution part for generating a clock signal and distributing the generated clock signal to a plurality of destinations, slots in each of which a clock reception unit can be detachably mounted, and a plurality of transmission lines coupling the clock generation and distribution part to the slots. Each slot includes a circuit for generating a mount state signal which indicates whether or not the slot is mounted with a clock reception unit, and for supplying the mount state signal to the clock generation and distribution part via a transmission line. This mount state signal has a first state when no clock receiving unit is mounted in the slot and has a second state when a clock receiving unit is mounted in the slot. The clock generation and distribution part includes a circuit for receiving the mount state signal from each slot and for transmitting via the transmission line the clock signal to each slot from which a mount state signal having the second state is received.

Clock distribution system

Growing community of inventors

Kawasaki, Japan

Akio Morimoto