Fig. 1. Principle diagram of φ-OTDR system

Fig. 2. φ-OTDR high-frequency vibration detection experiment system

Fig. 3. Signal demodulation process

Fig. 4. Detected original time domain signal

Fig. 5. Spectrum of original time domain signal

Fig. 6. Signal spectrum after demodulation

Fig. 7. Demodulated signals at vibration position. (a) Time domain; (b) frequency domain

Fig. 8. Spectrum of high-frequency vibration detection