Fig. 1. Experimental setup for Rayleigh BOTDA sensing system

Fig. 2. Process of cross-correlation convolution. (a) Brillouin gain spectrum; (b) ideal Lorentz curve; (c) cross-correlation convolution result

Fig. 3. Comparison of BFS extracted by two ways

Fig. 4. Comparison of BFS extracted by two ways in case of under-fitting

Fig. 5. BFS extraction results corresponding to different point numbers. (a) 30 points; (b) 20 points; (c) 10 points; (d) 4 points

Fig. 6. High-order extraction of BFS. (a) γ=60;(b) γ=1000;(c) eMSE; (d) comparison of extracted BFS of LCF and the proposed algorithm

Fig. 7. Comparison of BFS extraction results in two ways at scanning frequency intervals of (a) 10 MHz and (b) 20 MHz

Fig. 8. Processing methods adopted with nonideal Brillouin gain spectrum. (a) Brillouin gain spectrum; (b) cross-correlation convolution result; (c) LCF result; (d) Brillouin gain spectrum after symmetric cutting

Fig. 9. Cross-correlation convolution results and high-order BFS extraction.(a) Cross-correlation convolution result; (b) LCF result; (c) comparison of extraction results of LCF and the proposed method; (d) comparison of calculated BFS at 60 ℃ and 30 ℃