Inspired by the empirical mode decomposition (EMD)-enhanced gas detection work, this paper develops a further improved signal reconstruction method (namely EWT-ASG) for the demodulated harmonics of tunable diode laser absorption spectroscopy (TDLAS), which is mainly based on empirical wavelet transform (EWT) and Savitzky-Golay (S-G) filtering. First, the imported EWT performs better on the decomposition precision as it successfully bypasses the mode aliasing problem of EMD resulting by the lack of mathematical basis. Second, the improved S-G filter effectively suppresses the noisy components of the wavelet coefficients by updating its one key parameter (i.e., window size w) dynamically according to the correlation coefficients between the raw signals and the decomposed wavelet coefficients. The EWT-ASG scheme was first applied on the oxygen concentration detection for pharmaceutical glass vials. The preliminary experimental results indicate that the EWT-ASG method performs better than recent state-of-the-arts, with an average correct discrimination rate of 98.14% when the normalized SNR is 1. Even when the normalized SNR is degenerated from 1 to 0.85, our detection system still survived well, with a highest average correct discrimination rate of 90.45%. The detection system precision is also improved to a large extent, with a minimal Allan deviation of 0.856@(117s).

中文翻译：

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EWT-ASG：具有自适应 Savitzky 的经验小波变换——TDLAS 的 Golay 滤波

受经验模态分解（EMD）增强型气体检测工作的启发，本文针对可调谐二极管激光吸收光谱（TDLAS）的解调谐波开发了一种进一步改进的信号重建方法（即EWT-ASG），该方法主要基于经验小波变换 (EWT) 和 Savitzky-Golay (SG) 滤波。首先，导入的 EWT 在分解精度上表现更好，因为它成功地绕过了由于缺乏数学基础而导致的 EMD 模式混叠问题。其次，改进的SG滤波器根据原始信号和分解小波系数之间的相关系数动态更新其一个关键参数（即窗口大小w），有效地抑制了小波系数的噪声成分。EWT-ASG 方案首先应用于药用玻璃小瓶的氧浓度检测。初步实验结果表明，EWT-ASG 方法的性能优于最近的最新技术，当归一化信噪比为 1 时，平均正确识别率为 98.14%。即使归一化信噪比从 1 退化为 0.85 ，我们的检测系统仍然存活得很好，最高平均正确判别率为 90.45%。检测系统精度也有较大提高，最小艾伦偏差为0.856@(117s)。即使当归一化 SNR 从 1 退化到 0.85 时，我们的检测系统仍然能够很好地存活，最高平均正确识别率为 90.45%。检测系统精度也有较大提高，最小艾伦偏差为0.856@(117s)。即使当归一化 SNR 从 1 退化到 0.85 时，我们的检测系统仍然能够很好地存活，最高平均正确识别率为 90.45%。检测系统精度也有较大提高，最小艾伦偏差为0.856@(117s)。