Fig. 1. Structure diagram of φ-OTDR

Fig. 2. Comparison of the data presentation form between the time-space map and the time-domain curve

Fig. 3. Operation process of CNN and LSTM. (a) 1D convolution; (b) 2D convolution; (c) LSTM

Fig. 4. Schematic of the internal structure of φ-OTDR integrated system

Fig. 5. Structure diagram of BRNN (LSTM)

Fig. 6. Training situation and test results of LSTM. (a) Curve of loss function with dynamic learning rate; (b) curve of loss function with fixed learning rate; (c) background noise; (d) excavation signal; (e) motor vibration signal; (f) walking signal

Fig. 7. STFT results of target signals. (a) Background noise; (b) excavation signal; (c) motor vibration signal; (d) walking signal

Fig. 8. Network structure of LSTM-CNN

Fig. 9. Comparison of overall evaluation indicators. (a) Train accuracy; (b) test accuracy; (c) train loss; (d) test loss

Fig. 10. Recall comparison of test set. (a) Background noise; (b) excavation signal; (c) motor vibration signal; (d) walking signal

Fig. 11. Precision comparison of test set. (a) Background noise; (b) excavation signal; (c) motor vibration signal; (d) walking signal

Fig. 12. Precision of validation sample. (a) Background noise; (b) excavation signal; (c) motor vibration signal; (d) walking signal

Fig. 13. Recall of validation sample. (a) Background noise; (b) excavation signal; (c) motor vibration signal; (d) walking signal

Fig. 14. Precision of validation sample of models in Table 3. (a) Background noise; (b) excavation signal; (c) motor vibration signal;(d) walking signal

Fig. 15. Recall of validation sample of models in Table 3. (a) Background noise; (b) excavation signal; (c) motor vibration signal; (d) walking signal