Ansheng Zhao, Xu Yang, He Zhang, Zhilong Zhang. Research on Noise Reduction Method of Second-Harmonic Signal[J]. Laser & Optoelectronics Progress, 2023, 60(7): 0730001
- Laser & Optoelectronics Progress
- Vol. 60, Issue 7, 0730001 (2023)
Fig. 1. Wavelet threshold denoising process
Fig. 2. Flow chart of EMD-DFA-wavelet adaptive threshold denoising method
Fig. 3. Second harmonic signals. (a) Original second harmonic signal; (b) second harmonic signal with noise
Fig. 4. IMFs of signals with noise. (a) IMF1; (b) IMF2; (c) IMF3; (d) IMF4
Fig. 5. EMD-DFA-wavelet adaptive threshold noise reduction
Fig. 6. Comparison of original signal and EMD-DFA-wavelet adaptive threshold denoising signals
Fig. 7. Noise reduction effect diagram of different algorithms. (a) Use EMD-DFA to reduce noise; (b) use wavelet soft threshold to reduce noise; (c) use wavelet hard threshold to reduce noise; (d) use wavelet adaptive threshold to reduce noise
Fig. 8. System structure diagram
Fig. 9. Relationship between second harmonic amplitude and CO2 concentration before denoising
Fig. 10. Relationship between second harmonic signal and CO2 concentration after EMD-DFA-wavelet adaptive threshold noise reduction processing
Fig. 11. Linear fitting of relationship between amplitude of second harmonic and concentration of CO2
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Table 1.
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Table 2. Scale index of each order IMFs of second harmonic signal
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Table 3. Comparison of effects of various denoising methods
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