Fig. 1. Schematic diagram of phase-optical time domain reflectometer based on coherent detection

Fig. 2. Schematic diagram of the wavelet decomposition and reconstruction

Fig. 3. Experimental setup of phase-optical time domain reflectometer

Fig. 4. Phase demodulation in the phase-optical time domain reflectometer. (a) Coherence detection curves; (b) modulus values before low-pass filtering; (c) modulus values after low-pass filtering; (d) phase changes

Fig. 5. Result before wavelet noise suppression. (a) Three-dimensional demonstration of phase change; (b) phase changes while outliers have been removed; (c) correlation coefficient of approximate components; (d) the number of maximum correlation coefficient values

Fig. 6. Results after wavelet noise suppression. (a) Phase change after wavelet noise suppression; (b) the difference between the phase changes before and after the wavelet noise suppression; (c) phase change obtained by data fitting after wavelet noise suppression; (d) finally calculated phase signal

Fig. 7. Noise difference. (a) Difference between non-wavelet measurement value and non-wavelet true value; (b) difference between wavelet measurement value and non-wavelet true value; (c) difference between non-wavelet measurement value and wavelet true value; (d) difference between wavelet measurement value and wavelet true value

Fig. 8. The effect of polarization. (a) Distribution of the modulus values behind the reference point; (b) phase change in the position of polarization fading point; (c) phase change after wavelet noise suppression; (d) phase change in the non-polarization fading point