Zhaopeng Si, Bangning Mao, Zehua Bu, Huaping Gong, Ben Xu, Juan Kang, Chunjun Yang, Chunliu Zhao. Demodulation Analysis of Distributed Vibration Sensor Signals Based on Fast Fourier Transform[J]. Chinese Journal of Lasers, 2023, 50(5): 0506001
- Chinese Journal of Lasers
- Vol. 50, Issue 5, 0506001 (2023)
Fig. 1. DAS system structure diagram
Fig. 2. Flow chart of FFT vibration signal extraction
Fig. 3. Optical fiber directional phase unwinding diagram after phase difference of vibration points
Fig. 4. Unwinding diagram of phase difference in time direction and time-distance diagram of phase difference after unwinding of time direction. (a) Phase-time diagram with time direction unwinding; (b) diagram of phase difference with time-distance variation
Fig. 5. Phase-time diagrams of vibration signals extracted by three demodulation methods. (a) FFT demodulation; (b) IQ demodulation; (c) Hilbert transform demodulation
Fig. 6. Spectra of extracted signals by three demodulation methods. (a) FFT demodulation; (b) IQ demodulation; (c) Hilbert transform demodulation
Fig. 7. Power spectra of demodulation signals in three demodulation modes. (a) FFT demodulation; (b) IQ demodulation; (c) Hilbert transform demodulation
Fig. 8. Phase-time diagrams of intermediate- and high-frequency signals in FFT demodulation mode. (a) Intermediate-frequency signal of 2000 Hz; (b) high-frequency signal of 5000 Hz
Fig. 9. Signal spectra under FFT demodulation mode. (a) Intermediate-frequency signal of 2000 Hz; (b) high-frequency signal of 5000 Hz
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