Abstract: A transmission device includes a control card and a plurality of IF cards. The control card receives first set time from a host PC and calculates second set time by adding add time corresponding to one cycle of a clock signal that is commonly used by the control card and the IF cards to the first set time. The control card distributes the second set time to each of the IF cards. After each of the IF cards receives the second set time and sets the second set time in an internal timer, when a clock signal is detected, each of the IF cards starts a time measuring operation of the internal timer from the second set time.

Abstract: An optical transmission system includes a transmitting device and a receiving device, wherein the transmitting device includes a modulating unit that changes a frequency of an optical signal, and the receiving device includes a filtering unit that passes an optical signal in a predetermined frequency band; a measuring unit that measures an intensity of an optical signal that passes through the filtering unit; a detecting unit that detects a center wavelength of the optical signal in accordance with an intensity of the optical signal that is measured when a frequency of the optical signal is changed in a state of a passed band that corresponds to the optical signal; and an output unit that outputs information that indicates the detected center wavelength to the transmitting device, wherein the transmitting device controls a wavelength of the optical signal in accordance with the information from the receiving device.

Abstract: An optical transmitter includes a dummy optical source, a polarized wave beam coupler, and an auto gain control (AGC)-system amplifier. The dummy optical source outputs, out of an optical signal in which an optical path signal and an optical packet signal are mixed, a dummy signal having a wavelength identical to that of the optical packet signal. The polarized wave beam coupler multiplexes the dummy signal with the optical signal so that the dummy signal is orthogonal to the optical signal so as to output an output signal. The AGC-system amplifier inputs the output signal, and amplifies the output signal with a predetermined amplification factor corresponding to a power difference between input power and output power of an optical amplifier.

Abstract: A ring connection apparatus according to one embodiment is provided with: a frame receiver that receives frames to be transmitted to one of the plurality of ring networks from each of the plurality of networks; and a frame transmitter that transmits each of frames, a passing frame to be transmitted from a device to another device inside said one ring network and a crossing frame to be transmitted to a device in said one ring network from a device in another ring network different from said one ring network, to said one ring network within the range of a band, which is separately determined in advance.

Abstract: An optical packet switching system includes optical packet switching apparatus and an optical packet transmitting apparatus. The optical packet switching apparatus includes client optical delay units for delaying optical packet signals, network optical delay units for delaying one of the network optical packet signals, the network optical delay unit having a longer delay time than the client optical delay unit, an optical switch unit for switching the route of the inputted client optical packet signal so as to be sent out, an optical switch control unit for controlling the optical switch unit. The optical switch control unit is configured in such a manner as to detect a free time slot. The optical packet transmitting apparatus adjusts transmit timing, with which the client optical packet signal is sent out, in such a manner that the client optical packet signal is inserted into the free time slot.

Abstract: A client interface unit receives a pause frame transmitted from a client device compatible with a relatively low communication rate. A data rate conversion unit generates a plurality of pause frames in accordance with a pause time designated by the received one pause frame and transmits the plurality of pause frames to a frame processing unit compatible with a relatively high communication rate. The frame processing unit stops transmitting a frame destined to the client device in accordance with the plurality of pause frames.

Abstract: An optical packet transmitting/receiving system includes an optical packet transmitting apparatus for generating a copied optical packet signal of an original packet signal to be transmitted and for transmitting the copied optical packet signal after the original optical packet signal, an optical packet receiving apparatus for performing an error recovery processing based on the copied optical packet signal of the original optical packet signal, when an error occurs with the received original optical packet signal, and an optical packet switching apparatus. When congestion occurs between a copied optical packet signal inputted to an input port and an original optical packet signal inputted to another input port, the optical packet switching apparatus preferentially passes the original optical packet signal.

Abstract: A frame transmission system includes a frame transmitter and a frame receiver. The frame transmitter includes a frame fragmentation unit and a reproduction header appending unit. The frame fragmentation unit fragments an input frame and outputs transfer frames when the length of the input frame exceeds a predetermined fragmentation reference frame length, and does not fragment the input frame and outputs the input frame as a transfer frame when the length of the input frame is less than or equal to the fragmentation reference frame length. The reproduction header appending unit appends a reproduction header to the transfer frames outputted from the frame fragmentation unit. Here, the reproduction header being required when the transfer frames are reproduced at a receiving side. The reproduction header appending unit varies the header length of the reproduction header to be appended to the transfer frame, according to the length of the input frame.

Abstract: An optical transmission device that receives a wavelength division multiplexed optical signal obtained by dividing an optical packet signal and performing wavelength multiplexing and that transmits via an optical switch the received wavelength division multiplexed optical signal includes an optical power level measurement unit configured to measure respective optical power levels of respective optical signals of wavelengths included in the wavelength division multiplexed optical signal, and a routing information determinator configured to determine routing information of the wavelength division multiplexed optical signal on the basis of the measured optical power levels.

Abstract: An optical packet switching system includes an optical packet transmitter, an optical packet switching apparatus, an optical amplifier, an optical packet receiver, an information gathering unit, and a peak power calculation unit. The information gathering unit collects the packet density, time-averaged power and extinction ratio from the optical packet transmitter, collects the packet density, time-averaged power and noise figure from the optical amplifier, collects the packet density, time-averaged power, switch on/off time ratio and extinction ratio from the optical packet switching apparatus, and collects the packet density and time-averaged power from the optical packet receiver. The peak power calculation unit calculates the peak power of an optical packet signal outputted from each apparatus/device based on the collected information.

Abstract: A frame transmission system includes a frame transmitter and a frame receiver. The frame transmitter includes a frame fragmentation unit and a reproduction header appending unit. The frame fragmentation unit fragments an input frame and outputs transfer frames when the length of the input frame exceeds a predetermined fragmentation reference frame length, and does not fragment the input frame and outputs the input frame as a transfer frame when the length of the input frame is less than or equal to the fragmentation reference frame length. The reproduction header appending unit appends a reproduction header to the transfer frames outputted from the frame fragmentation unit. Here, the reproduction header being required when the transfer frames are reproduced at a receiving side. The reproduction header appending unit varies the header length of the reproduction header to be appended to the transfer frame, according to the length of the input frame.

Abstract: A component mounting method includes: placing a mounting component in contact with, and on top of, an electronic component on a substrate, pressing a spring member against the mounting component using a jig such that the mounting component is pushed against the electronic component by the spring member, and fixing the spring member to the substrate, and removing the jig in a direction heading away from a mounting face of the substrate after the spring member has been fixed to the substrate.

Abstract: An optical packet switching system includes a plurality of network elements for transmitting and receiving optical packet signals. Each network element includes an optical signal-to-noise ratio (OSNR) acquiring unit for acquiring the OSNR of each optical packet signal, an average value calculating unit for calculating the average value of the OSNRs of optical packet signals received within a predetermined time duration for each of the plurality of source network elements, and a difference information transmitter for calculating the difference between the calculated average value of the OSNRs and a target value of the OSNRs and then transmitting the difference to a network element corresponding to the difference. A source network element that has received the difference information adjusts the characteristics of an optical packet signal to be transmitted in a manner such that the difference is reduced.

Abstract: A frame transmission apparatus includes multiple ports provided in a line unit, and a setting control unit. The setting control unit checks the normality of the frame transfer state within the apparatus by transferring a maintenance management frame from a first port to a second port within the apparatus. When the first port is a logical port configured by link aggregation of multiple physical ports, the setting control unit selects each of the multiple physical ports as a transmission source port and transfers multiple maintenance management frames from the multiple physical ports to the second port.

Abstract: A communication system includes a plurality of communication devices forming a ring network and a monitoring device. Each of the plurality of communication devices appends, to a frame that the communication device relays, an ID tag indicating the number of communication devices relaying that frame in the ring network. The monitoring device refers to frames received by a predetermined communication device and having the ID appended thereto, and tallies an amount of data for frames for each number of relaying communication devices.

Abstract: In a full bridge type DC-DC converter, a first protective diode is connected between a first node between a first resonance inductor on a primary side and one terminal of a primary winding of a transformer, and a power line on a high voltage side of a power supply. A second protective diode is connected between the first node and a power line on a low voltage side of the power supply. A third protective diode is connected between a second node between a second resonance inductor and the other terminal of the primary winding, and the power line on the high voltage side of the power supply. A fourth protective diode is connected between the second node and the power line on the low voltage side of the power supply.

Abstract: A plurality of frame buffers of a communication device store input frames for respective flows, which are units of managing communication. A sequential scheduler and an adjustment scheduler cyclically visit the plurality of frame buffers to read a frame for external output from each frame buffer. The sequential scheduler reads one frame per a visit to each frame buffer at a speed lower than a communication speed of the communication device. The adjustment scheduler reads one or more frames per a visit to each frame buffer such that a restriction on read quantity defined by a reference value greater than the shortest frame size is imposed.

Abstract: An excitation light source, for Raman amplification, includes a polarization beam splitter (PBS) for splitting a laser beam from an excitation laser into two polarization components, and a polarization beam combiner (PBC) for combining the two polarization components, and a time difference generator provided between PBS and PBC. The time difference generator generates a difference in propagation time between the two polarization components.

Abstract: A communication apparatus forming a ring network sends a test frame that is not designed to be discarded at a block point in the ring network established to discard the user frame and that is configured to have a data size randomly selected from the data sizes permitted for the user frame, from a first communication port connected to a transfer channel in a first direction in the ring network. The communication apparatus determines that the transfer status of the user frame in the ring network is normal when the sent test frame is received via a second communication port connected to a transfer channel in a second direction in the ring network in a predetermined manner.

Abstract: An optical receiving device includes: an optical amplifier configured to amplify a wavelength multiplexed optical signal; a demultiplexer configured to demultiplex the amplified wavelength multiplexed signal into optical signals of a plurality of wavelengths; optical receivers configured to regenerate the demultiplexed optical signals; error correction units configured to correct a bit error in the regenerated optical signals; and main control unit. The control unit adjusts RXDTV of the optical receiver for receiving optical signals of a given wavelength to the optimal value in the state where the gain of the optical amplifier is lowered from that of a normal operation such that the occurrence of bit errors in the optical signals of the other wavelengths does not exceed the correction capability of the error correction unit.