Fig. 1. System structure diagram

Fig. 2. Optical time domain reflection traces when loaded with vibration event

Fig. 3. 100 traces after the relative intensity ratio method

Fig. 4. Dynamic range

Fig. 5. Process diagrams of obtaining the dynamic range by subtracting the noise level and logarithmic transformation

Fig. 6. Subtract the noise base and use the relative intensity ratio legal bit

Fig. 7. Local magnification of optical time domain reflectometry data traces

Fig. 8. Improved relative intensity ratio method

Fig. 9. Dynamic range of the improved system

Fig. 10. SNR of system positioning under different noise level

Fig. 11. Performance of the system at different noise levels