| 摘要 |
PURPOSE:To separately obtain a pulse of each channel from an output signal of a photodetector, by transmitting optical pulses of plural channels whose optical power is different, in the transmitting side, transmitting them by an optical fiber, and photodetecting them by one photodetector. CONSTITUTION:Light sources 2-4 are driven by driving circuits 6-8, generate optical pulses different in optical powers P1-P3, and they are transmitted through a branch type optical fiber 1. Optical pulse signals from the light sources 2-4 are converted to voltage V1-V3 proportional to a photocurrent, by a photodetector of a photodetecting circuit 5, are amplified to a constant level by an amplifier 9, and are inputted to a signal separating circuit 10. In the receiving side, the optical pulses appear in a superposed form, and in case when 3 optical channels exist, signals (1)-(7) of 7 kinds of receiving voltage levels appear. In the signal separating circuit 10, the pulse signals of each channel are separated by reference voltage levels Ref1-Ref7 being in the middle of 7 kinds of receiving voltage levels. |
