Abstract: In a wavelength division multiplexing transmission system, a controller of a relay node of a post-stage notifies level decrease information to a transmission node, upon detecting a decrease in a level of a wavelength in a wavelength multiplex signal received from the transmission node of a pre-stage by the optical channel monitor of the transmission node. The controller of the transmission node of the pre-stage determines that a failure occurs in the wavelength of the transponder of the transmission node, upon detecting a decrease in the level of the wavelength in the wavelength multiplex signal transmitted to the relay node by the optical channel monitor of the transmission node and upon receiving the level decrease information for the wavelength from the relay node. Therefore, a wavelength channel failure in the transponder can be determined in a preferable manner.

Abstract: A transmission system is provided with a transmission apparatus that outputs an ASE light from a transmission light amplifier and with a reception apparatus provided with: a tilt detection unit that detects the optical strength levels of at least two probe lights having different wavelengths from a received ASE light; and a reception light amplifier that performs a first-order tilt correction on light to be output in a linear manner so as to reduce the difference in the optical strength level of the two probe lights detected by the tilt detection unit.

Abstract: An integrated transmission apparatus includes a plurality of optical supervisory channel (OSC) processing units for processing OSC signals contained in a wavelength division multiplexing (WDM) signal received from a WDM network and a switching unit for performing the path control of synchronous digital hierarchy (SDH) frames. An OSC processing unit transmits the SDH frame, containing wavelength information indicated by, to the switching unit. Another OSC processing unit acquires the SDH frame, containing wavelength information, from the switching unit and sets an OSC signal which is to be appended to the WDM signal to be transmitted, based on the wavelength information.

Abstract: An integrated transmission apparatus includes a plurality of optical supervisory channel (OSC) processing units for processing OSC signals contained in a wavelength division multiplexing (WDM) signal received from a WDM network and a switching unit for performing the path control of synchronous digital hierarchy (SDH) frames. An OSC processing unit transmits the SDH frame, containing wavelength information indicated by, to the switching unit. Another OSC processing unit acquires the SDH frame, containing wavelength information, from the switching unit and sets an OSC signal which is to be appended to the WDM signal to be transmitted, based on the wavelength information.

Abstract: A transmission system is provided with a transmission apparatus that outputs an ASE light from a transmission light amplifier and with a reception apparatus provided with: a tilt detection unit that detects the optical strength levels of at least two probe lights having different wavelengths from a received ASE light; and a reception light amplifier that performs a first-order tilt correction on light to be output in a linear manner so as to reduce the difference in the optical strength level of the two probe lights detected by the tilt detection unit.

Abstract: A method of controlling an optical wavelength division multiplexing transmission apparatus achieves stable wavelength division multiplexing optical transmission by switching a control mode of an optical amplification section in accordance with an input state of optical signals of various wavelengths. Accordingly, the method involves, upon startup of the optical wavelength division multiplexing transmission apparatus, initial setting of information such as the wavelengths being used and the number of wavelengths being used, setting the amount of optical attenuation for each wavelength to a maximum value, and setting an optical amplification unit to ALC.

Abstract: A WDM transmission device includes a level adjustment unit adjusting levels of optical signals having different wavelengths, a multiplexer multiplexing the optical signals, an amplifier amplifying a multiplexed optical signal, and a monitor unit monitoring the multiplexed optical signal applied to the amplifier and a level of an output signal of the amplifier and controlling the level adjustment unit so that the levels of the optical signals fall within a predetermined level range in which the amplifier can operate normally.

Abstract: A method of controlling an optical wavelength division multiplexing transmission apparatus achieves stable wavelength division multiplexing optical transmission by switching a control mode of an optical amplification section in accordance with an input state of optical signals of various wavelengths. Accordingly, the method involves, upon startup of the optical wavelength division multiplexing transmission apparatus, initial setting of information such as the wavelengths being used and the number of wavelengths being used, setting the amount of optical attenuation for each wavelength to a maximum value, and setting an optical amplification unit to ALC.

Abstract: A packet communications method whereby reliable and high-speed communication is possible without depending on the processing of other layers, and also whereby the system configuration can be flexibly changed without making circuit changes to the receiving unit. A device on the sending side adds a packet identifier to the packet and sends this packet along with a packet identical to this packet to a device on the receiving side. The device on the receiving side receives the packets sent from the device on the sending side, checks the packets for errors and, based on the packet identifier, determines whether or not the error-free packets have arrived first. If the packet arrived first, the packet with the packet identifier removed is subject to sending to a terminal, but if it arrived last, the packet is not subject to sending to the terminal, so only error-free packets are subject to the determination of whether it arrived first or not, and thus the determination can be performed accurately.

Abstract: A dome-shaped roof structure for a large construction such as an athletic stadium is capable of being partly opening according to the environmental conditions such as the weather. The dome-shaped roof structure includes a dome-shaped stationary roof section having a central opening and fixedly secured at an outer periphery thereof to the external wall of the construction, and a plurality of movable roof units each having a shape to cover one of a plurality of divisions of the central opening and pivotably secured at one end thereof to a support located near the circumference of the central opening so as to be turned between a first position where the central opening is closed and a second position where the same is opened.