| 摘要 |
PURPOSE:To operate the circuit even any optical signal input level by changing a gain control voltage in an intermittent power supply period in a triangle form from '0' to a maximum. CONSTITUTION:The optical reception circuit consists of a photodetector 1, a preamplifier 2, an automatic gain control circuit 3, a pilot extracting circuit 4, a rectifier 5, a differential amplifier 6, a reference voltage 10, an intermittent power supply gain control signal selection circuit 7, an intermittent power supply gain control signal generating circuit 8, an optical signal input identification circuit 11, an intermittent power supply selector switch 12 and an active power supply selector switch 13. The intermittent power supply pulse 17 is fed to the circuit over a power supply period t0sec. When an optical signal input 22 is inputted within the period t0, a pilot signal is extracted by a pilot extraction circuit 4, rectified by the rectifier circuit 5, identified by the input identification circuit 11 to turn off the switch 12 and to turn on the switch 13. Simultaneously, the selector circuit 7 is set to the input signal 20 of the normal operation from the signal generating circuit 9. |
