基于变分模态分解和SG滤波的二次谐波降噪

Second Harmonic Denoising Based on Variational Mode Decomposition and SG Filtering

针对可调谐半导体激光器吸收光谱学,在测量低浓度气体过程中二次谐波存在的噪声问题,提出利用变分模态分解(VMD)和Savitzky-Golay滤波(SG滤波)相结合方法(简记为VMD-SG滤波)对含噪信号进行降噪。分析了VMD平衡参数的最优选取,利用所设框长调节因子P,选取SG滤波的最优框长。通过与其他几种降噪算法相比,VMD-SG滤波降噪算法在信噪比、均方根误差、波形恢复、二次谐波特征点误差方面均表现较优。在信噪比(SNR)为-7.8389 dB下该算法SNR提升量为22.047 dB,均方根误差为0.0154,与标准二次谐波相关系数为0.985。结果表明,基于VMD-SG滤波降噪算法的可调谐二极管吸收光谱复合降噪技术,在弱信号方面可以提高信号质量,有利于提高气体反演精度、系统检测灵敏度。

The combination of Variational mode decomposition(VMD)and Savitzky-Golay filtering(SG filtering),abbreviated as VMD-SG filtering,was suggested for the reduction of noise in signals containing noise,with a particular emphasis on the absorption spectroscopy of tunable semiconductor lasers and the issue of noise in the second harmonic during the measurement of low concentration gases.The optimal selection of VMD balance parameters was analyzed,and the set frame length adjustment factor P was utilized to select the optimal frame length for SG filtering.When compared with other denoising algorithms,it was found that the VMD-SG filtering denoising algorithm performed better in terms of signal-to-noise ratio,root mean square error,waveform recovery,and the error of the second harmonic feature point.At signal-to-noise ratio(SNR)of-7.8389 dB,an improvement of 22.047 dB in SNR was achieved by the algorithm,a root mean square error of 0.0154 was recorded,and a correlation coefficient of 0.985 with the standard second harmonic was determined.The results were indicative of the fact that the tunable diode absorption spectrum composite denoising technology,which was based on the VMD-S-G filtering denoising algorithm,could more effectively enhance the quality of signals in weak signal conditions.It was also found to be beneficial for enhancing the accuracy of gas inversion and the sensitivity of system detection.