| 摘要 |
PURPOSE:To omit an automatic threshold control circuit by discriminating the level of a signal transmitted through a 2nd optical fiber on the basis of a reference signal transmitten through a 1st optical fiver, by providing 1st and 2nd optical fibers for reference signal transmission and photo signal transmission. CONSTITUTION:A reference signal from optical fiber F1 for reference signal transmission is converted by photo detecting element 1'a into an electric signal, which is applied to comparators CON2-CONn through amplifier A1 and LPF. Signals from optical fibers F2-Fn for photo signal transmission, on the other hand, are converted by photo detecting elements 2'a-n'a into electric signals, which are applied to comparators CON2-CONn through amplifiers A2-An. Then, comparators CON2- CONn make comparisons with the reference signal supplied through LPF to discriminate respective signal levels. This constitution eliminate the need for an automatic threshold control and also provides the simplification of the entire constitution of this unit. |
