| 摘要 |
PURPOSE:To ensure a monitor for the optical reception level without breaking the optical signal, by monitoring the potential difference of the resistance which is connected as a load to the photodetector in the receiving device of an optical communication system. CONSTITUTION:When the light is put into the photodetector 1, the current flows to the detector 1 in accordance with the power of the light. This current then flows between the base and the emitter of the transistor TR1, and thus the TR1 is turned on. As a result, the transistor TR2 is also turned on to obtain an output from the collector. On the other hand, the voltage is produced at the resistances R1 and R2 connected to the detector 1 and in accordance with the power of the light given to the detector 1. This voltage is smoothed by the smoothing circuit 2 and then amplified by the amplifier 3 to be sent out. The output of the amplifier 3 is proportional to the power of the light put into the detector 1. Thus the light receiving level can be monitored by monitoring the output of the amplifier 3. |
