| 摘要 |
PURPOSE:To enable the reception of discontinuous optical signal different remarkably from optical power, by providing a plurality of amplifier circuit, detecting the amplifier circuit output having unsuitable amplitude and adopting this output. CONSTITUTION:Optical signals detected at a photodetector 21 are sequentially input to amplifiers 31-33. The output of each amplifier is fed to identifying circuits 41, 42, 43, which output 1 to the signal selection circuit when the output is more than a value, and 0 when less than a value. The output of the amplifiers 31, 32 is fed to detection circuits 51, 52 also, and the detection circuits output 1 to the signal selection circuit 61 when the amplitude of signal is more than specified threshold value, and 0 when less than it. The signal selection circuit 61 adopts the signal of the identification circuit 41 when the output of the detection circuit 51 is 1 for the output, it adopts the signal of the circuit 42 when the output of the detection circuit 51 is 0 and the output of the circuit 52 is 1, and the output of the circuits 51, 52 are both 0, it adopts the signal of the circuit 43. |
