Fig. 1. Experimental system setup diagram

Fig. 2. Comparison of the Rayleigh spectra of the 5th to 8th probe pulses and the first probe pulse at the same position

Fig. 3. Comparison of strain waveforms. (a) With cubic spline interpolation; (b) without cubic spline interpolation

Fig. 4. Results of strain demodulation. (a) Strain signal in 20 ms; (b) power spectral density of strain signal, where the SNR is 32.5 dB; (c) frequency shift at near end of fiber, the stripes represent vibration at this position; (d) standard deviation of (c) on each point of fiber, where the distance between 10% and 90% of the edge is about 1 m, which is also the spatial resolution of the system

Table 1. Performance comparison of demodulation methods along fiber axial direction and frequency axis direction