CO在1. 578 μ m的可调谐二极管激光光谱信号小波去噪研究

研究了一氧化碳(CO)近红外波段直接吸收和波长调制信号去噪处理算法。从HATRAN数据库中得到CO气体的吸收信号作为仿真数据，提取直接吸收信号、1-f和2-f解调信号作为原始信号，研究了不同小波基以及不同的分解层数对叠加高斯白噪声的光谱信号去噪的效果。最后利用基长为0.95 m有效光程为55.1 m的Herriott型多光程池对CO在1.578 μm处的第二泛频带P(4)吸收谱线信号进行测量和信号处理，与原始信号相比，经过信号处理过的直接吸收、1-f和2-f解调信号的信噪比都提高1～2个数量级；通过选择不同小波基和优化小波变换层数，增加了系统的抗干扰能力。

Wavelet Denoising Research for the Tunable Laser Diode Absorption Spectroscopy of the CO at 1.578 μm

The signals processing algorithm is presented based on laser spectroscopy direct absorption signal (DAS) and wavelength modulation spectroscopy (WMS) for the trace carbon monoxide (CO) measurement. The simulated transmittance data of the pure CO gas are from the HATRAN database. The DAS intensity, appending WMS 1-f and WMS 2-f signal intensities are used as the raw signals. Aimed to obtain optimized filtering algorithm, those raw signals which were added Gaussian white noise are denoised by using diverse wavelet-bases and decomposition layers. The effectiveness is validated by our CO concentration detection experiment which measures the weak laser absorption spectral line P(4) of second overtone band at 1.578 μm. A 0.95 m Herriott-type cell provides an effective absorption path length of 55.1 m. Comparing the sensing performances without and with using the optimized wavelet, the experimental results show that the signal-to-noise ratios of the system are significantly improved by 1 to 2 orders of magnitude for the DAS, 1-f and 2-f signal. The anti-jamming capability of the system is improved by proposing the suitable wavelet-base and decomposition layer algorithm.