A methane detection system based on tunable diode laser absorption spectroscopy (TDLAS) using LabVIEW platform was demonstrated. To suppress the noise interference in the system, a wavelet denoising method was studied and experiments with different parameters were carried out. With the threshold of Hard, the wavelet basis of Coif5 and the rule of Heursure, high frequency noises of the sensor can be effectively decreased with the harmonic amplitude increased. Experiments showed that, the 1σ minimum detection limit (MDL) was 23.68 ppbv (part per billion of volume) with an integration time of 300 s.

中文翻译：

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基于LabVIEW的小波去噪TDLAS甲烷检测系统

演示了使用 LabVIEW 平台的基于可调谐二极管激光吸收光谱 (TDLAS) 的甲烷检测系统。为了抑制系统中的噪声干扰，研究了一种小波去噪方法，并进行了不同参数的实验。采用Hard阈值、Coif5小波基和Heursure法则，可以有效降低传感器的高频噪声，提高谐波幅值。实验表明，1 σ最小检测限 (MDL) 为 23.68 ppbv（体积的十亿分之一），积分时间为 300 秒。