Fig. 1. Decoding principle of Golay encoding BOTDA

Fig. 2. BOTDA noise reduction process based on DnCNN

Fig. 3. Structure diagram of DnCNN

Fig. 4. BOTDA experimental setup

Fig. 5. Comparison of BGS matrixes under different measurement methods. (a) Single pulse; (b) Golay; (c) Golay+DnCNN

Fig. 6. Comparison of BGS matrixes at temperature change area under different measurement methods. (a) Single pulse; (b) Golay; (c) Golay+DnCNN

Fig. 7. Comparison of BGS matrixes at different positions of optical fiber under different measurement methods. (a) 5.0 km; (b) 50.0 km; (c) 99.7 km

Fig. 8. Comparison of BFS under different measurement methods, with illustration of BFS in temperature change area

Fig. 9. Comparison of RMSE under different measurement methods

Fig. 10. BFS obtained by fusion method, with illustration of BFS in temperature change area

Fig. 11. BFS obtained by monopulse cumulative average method, with illustration of BFS in temperature change area

Fig. 12. Comparison of spatial resolution and measurement time under different methods. (a) Spatial resolution under cumulative single pulse average; (b) spatial resolution under fusion method; (c) measurement time of both methods

Fig. 13. Comparison of effect of different denoising algorithms, with illustration of BFS in variable temperature zone

Fig. 14. BFS obtained by fusion method at different temperatures, with illustrations of BFS in temperature change area (left) and linear fitting curve (right)