Abstract: A signal quality monitoring method with reliability is disclosed. After extracting a clock signal from the light signal, a decision region is set for each bit of the light signal. The decision region is defined by a plurality of threshold amplitudes corresponding respectively to threshold phases which are produced with respect to the clock signal. The quality of the light signal is monitored depending on whether an amplitude of the light signal falls into the decision region at timings of the N threshold phases.

Abstract: An optical wavelength division coupler 11 wavelength-divides a wavelength multiplexed light to respective wavelength lights each of which is dropped to an optical gate switch 15-i (i=I˜n) and a light receiver 13-i by an optical coupler 12-i and supplied to an optical light fault monitor 14 through the light receiver 13-i. When the optical signal deterioration monitor 14 detects an optical loss of wavelength (OLOW), an optical loss of signal (OLOS) or an optical signal degrade (OSD) in wavelength lights processed by the optical coupler 12-i as a fault detection signal in an optical layer, a controller 19 controls the optical gate switch 15-i to cut off wavelength light passing therethrough and sends an optical alarm indication signal (AIS-O) to a downstream side. Therefore, when a loss of signal is detected by the light receiver 13-i, the optical signal deterioration monitor 14 can know the alarm indication signal (AIS) from the upstream side, removing the necessity of special hardware therefor.

Abstract: Optical regenerative relay amplifier 102 has a function for monitoring the power of optical signals from an optical fiber 101, and issuing an optical signal trouble detection signal (AIS (Alarm Indication Signal)) for shutting down the optical power in case that optical signal inputs are lost, and notifying the trouble, and optical ADMs 103 have a wavelength path selecting function, a wavelength path bundle function, and a wavelength path trouble or quality monitoring function in addition to an AIS issue function, and the optical cross-connect systems 104 have an AIS issue function, a function for monitoring a trouble or quality deterioration of optical signals for every wavelength path, a wavelength path grooming function, and a wavelength path protection function, and the terminal stations 105 transmit and receive services by optical signals having predetermined wavelengths, and monitoring a trouble or quality deterioration of optical signals for every wavelength path is conducted without depending on signa

Abstract: An optical wavelength division coupler 11 wavelength-divides a wavelength multiplexed light to respective wavelength lights each of which is dropped to an optical gate switch 15-i (i=1˜n) and a light receiver 13-i by an optical coupler 12-i and supplied to an optical light fault monitor 14 through the light receiver 13-i. When the optical signal deterioration monitor 14 detects an optical loss of wavelength (OLOW), an optical loss of signal (OLOS) or an optical signal degrade (OSD) in wavelength lights processed by the optical coupler 12-i as a fault detection signal in an optical layer, a controller 19 controls the optical gate switch 15-i to cut off wavelength light passing therethrough and sends an optical alarm indication signal (AIS-O) to a downstream side. Therefore, when a loss of signal is detected by the light receiver 13-i, the optical signal deterioration monitor 14 can know the alarm indication signal (AIS) from the upstream side, removing the necessity of special hardware therefor.

Abstract: A wavelength multiplexing optical transmitter 100 comprises a laser driving circuit 102 for driving a multi-mode oscillation semiconductor laser 101 and an optical filter 103 for filtering an optical output from said multi-mode oscillation semiconductor laser 101. An electric signal in a desired code form is input in the wavelength multiplexing optical transmitter 100. The electric signal input into the wavelength multiplexing optical transmitter 100, after being introduced into the laser driving circuit 102 in the wavelength multiplexing optical transmitter 100, executes a direct current modulation of the multi-mode oscillation semiconductor laser 101. The multi-mode oscillation semiconductor laser 101 outputs optical signals in response to the electric current input from the laser driving circuit 102.

Abstract: In an optical transmission system comprising an optical branch unit, first through fourth OR/OS pairs each of which includes optical receiver and optical transmitter, optical switch devices for active and standby systems, each of the optical switch devices having an N number of input ports and M number of output ports; and an optical multiplexer for multiplexing an M number of optical signal supplied from the third OR/OS pair and an M number of optical signals supplied from the fourth OR/OS pair to produce an M number of optical signals, the optical switch devices and the first through the fourth OR/OS pairs have a 3-dB margin with respect to the input optical strength. First and second paths are each adjusted such that the time required for transmitting an optical signal is identical for all paths.

Abstract: A sample is treated with a phosphoglyceric acid mutase (PGAM) inhibitor (polythionic acid (salt) such as potassium tetrathionate) to inactivate the M-type isozyme activity and the B-type PGAM is quantified by determining PGAM isozymes by a rate assay. The B-type PGAM is a novel marker for cerebral apoplexy, and the diagnosis of cerebral apoplexy is enabled by assaying it.