Fig. 1. Structure diagram of distributed optical fiber sensor

Fig. 2. External damage event feature extraction and detection process

Fig. 3. Monitoring and early warning system for external damage prevention

Fig. 4. Beat signal output after o/e conversion

Fig. 5. VGA control voltage

Fig. 6. Different amplitude of disturbance signal

Fig. 7. Loss curve and accuracy change curve

Fig. 8. Recognition rate of system early warning monitoring under different construction disturbance conditions