SYSTEM AND METHOD FOR MEASURING QUALITY OF LIGHT TRANSMITTING LINE AND LIGHT TRANSMITTING DEVICE

摘要

PROBLEM TO BE SOLVED: To estimate the degree of margins of a light transmission line with higher accuracy. SOLUTION: A light transmitting station 10 outputs signal light modulated by data for measuring error rates to an SNR regulating device 12. The SNR regulating device 12 combines noise light with the output light of the light transmitting station 10. The intensity of noise light can be regulated by a variable attenuator 28. Signal light and noise light are transmitted through an optical fiber transmission line 14 and inputted to a light receiving station 16. In the light receiving station 16, light inputted from the optical fiber transmission line 14 is partially branched by an optical coupler 32 and inputted to a spectrum analyzing device 34, and the rest is inputted to a light receiving device 36 to demodulate data. The data demodulated at the light receiving device 36 is inputted to an error rate measuring device 38. The SNR of the input signal light of the light receiving station 16 is known by the spectrum analyzing device 34. The error rate measuring device 38 measures the error rate of signal light. The degree of margins of SNR is determined from measurement results to each regulation of the SNR regulating device 12.