Fig. 1. φ-OTDR system based on coherent detection

Fig. 2. Three-layer wavelet packet decomposition

Fig. 3. Binary confusion matrix

Fig. 4. Experimental environment

Fig. 5. Location results of three disturbance signals

Fig. 6. Typical time domain waveforms of four different signals

Fig. 7. Typical energy spectrum of three-layer wavelet packet decomposition

Fig. 8. Average energy distribution of four differrent events

Fig. 9. Signal recognition results of SVM