Fig. 1. Flow chart of the variable step scanning strategy

Fig. 2. Schematic diagram of wave crest migration

Fig. 3. Fiber Bragg grating interrogation scheme based on DBR laser

Fig. 4. Lookup table for DAC codeword corresponding to current and ROM address

Fig. 5. Relationship of the laser output wavelength and the sampling address

Fig. 6. Threshold segmentation diagram when SNR is 7.87 dB

Fig. 7. Threshold segmentation diagram when SNR is 9.23 dB

Fig. 8. Sampled data

Fig. 9. The average peak-seeking error of scanning with different fixed step sizes and the variable step scanning strategy at different SNR

Fig. 10. Histogram and normal distribution fitting plot of the probability distribution of peak-seeking error under the four scanning modes when \begin{document}${SNR} = 13.65$\end{document} dB

Fig. 11. Histogram and normal distribution fitting plot of the probability distribution of peak-seeking error under the four scanning modes when \begin{document}${SNR} = 38.25$\end{document} dB