| 摘要 |
PURPOSE: To stably demodulate a light pulse transmitted over a long distance. CONSTITUTION: A light source 20 sends frequency-modulated light S20 to a light gate 30 by the current driving of a signal generator 10. The light gate 30 converts the frequency modulated light S20 to the light pulse S30 by a timing generator 40. The light power of a part of the light pulse S30 is directly returned to an O/E converter 60 via couplers 91, 92 for synchronizing signal. A returned light pulse is timing-detected by a frame synchronizing detector 100, and sent to the timing generator 40, and the sampling timing of a time series signal is generated. The light pulse S30 sent to a sensor array part 50 passes a delay fiber 93. The light pulse passing each stage of the sensor array part 50 goes to a time division signal system, and after it is channel-selected by sampling by a demultiplexer 70, it is converted to a continuous signal. Moreover, it is phase-demodulated by a phase demodulator 80, and goes to an acoustic signal. |
