Fig. 1. Schematic diagram of Φ-OTDR system

Fig. 2. Six types of one-dimensional time signals. (a) Background noise; (b) stone knocking; (c) stone stroking; (d) branch stroking; (e) longitudinal pulling; (f) climbing

Fig. 3. Schematic of GASF and GADF encoding

Fig. 4. Wavelet denoising process

Fig. 5. Effect picture of wavelet denoising. (a) Background noise; (b) stone knocking; (c) stone stroking; (d) branch stroking; (e) longitudinal pulling; (f) climbing

Fig. 6. Schematic diagram of GAF coding for 6 types of signals. (a) Window partition signal; (b) schematic diagram of GADF coding; (c) schematic diagram of GASF coding

Fig. 7. Test set accuracy of different encoding methods

Fig. 8. Architecture of the HorNet

Fig. 9. Loss curves of training

Fig. 10. Precision curves of training

Fig. 11. Confusion matrix

Fig. 12. Training accuracy of different neural networks

Fig. 13. Precision of different neural networks