Signal light processing apparatus

摘要

A signal processing apparatus sets a discrimination level most suitably, regardless of whether the apparatus is in the minimum receiving system or the maximum receiving system. The apparatus comprises a light receiving unit (1,2) converting input signal light to an electric signal, and a level detecting unit (4) for detecting a high level component and a low level component of the electric signal from the light receiving unit (1,2), along with peak levels on a high-side and a low-side of the electric signal.