Fig. 1. Distribution of scattered light in optical fiber

Fig. 2. Principal schematic of OTDR

Fig. 3. Schematic of ROTDR system structure

Fig. 4. Schematic of the structure of the BOTDR system

Fig. 5. Schematic of the structure of the POTDR system

Fig. 6. Schematic of the structure of the coherent detection type Φ-OTDR system

Fig. 7. Schematic of optical fiber vibration caused by line galloping

Fig. 8. Framework diagram of status evaluation on transmission line

Fig. 9. Schematic of OPGW lightning strike positioning