Method and apparatus to determine a discrimination threshold of a received signal, and an optical transmission system

摘要

A method to determine a discrimination threshold of a received signal input from an optical transmission line comprises steps of measuring a bit error rate of the received signal at each of a plurality of discrimination thresholds by changing a polarization direction of an optical signal to enter the optical transmission line to detect the worst bit error rate at each discrimination threshold, and searching a predetermined bit error rate from the plurality of the detected worst bit error rates and searching a discrimination threshold of the received signal according to the predetermined bit error rate.