DEVICE AND METHOD FOR REDUCING MEASUREMENT ERROR BY TRANSMISSION CHARACTERISTIC ACCORDING TO WAVELENGTH OF BAND PASS OPTICAL VARIABLE FILTER WHEN MEASURING OPTICAL SIGNAL TO NOISE RATIO OF OPTICA

摘要

PURPOSE: A device and a method for reducing a measurement error by a transmission characteristic according to wavelength of a band pass optical variable filter, when measuring an optical signal to noise ratio of an optical signal in optical communication, are provided to maximumly reduce the measurement error caused by a bad transmission characteristic, so that the performance of a WDM(Wavelength Division Multiplexing) optical transmission system can be monitored. CONSTITUTION: A D/A(Digital-to-Analog) converter(200) converts digital electric signals into analog electric signals to control a peak transmission wavelength of a band pass optical variable filter(300). A low pass filter(100) limits a frequency band of the converted analog electric signals. The band pass optical variable filter(300) in which the peak transmission wavelength is changed according to the analog electric signals. An automatic temperature regulator(700) fixes an operating temperature of the band pass optical variable filter(300). An optical detector(400) converts the strength of light transmitting the band pass optical variable filter(300) into analog electric signals. An A/D(Analog-to-Digital) converter(500) samples the analog electric signals transmitted from the optical detector(400) at a given cycle, to convert the sampled analog electric signals into digital electric signals. And a signal processor(600) measures an optical signal to noise ratio of optical signals using the converted digital electric signals.