关键词: 小波分析；直接吸收谱；可调谐半导体激光吸收谱技术；噪声消除；分布反馈半导体激光器

Abstract: In order to eliminate the signal noise of the direct absorption spectrum，the separation of high and low frequency portions of the signal noise was achieved by using wavelet analysis. The direct absorption signal was generated by several steps，such as light generation by distributed feedback (DFB) diode laser，gas absorption，data acquisition. Using the method mentioned above，the high frequency noise of the signal was eliminated. After the de-noising experiment of two signals，the de-noised signals reflected the spectral characteristics of the data，which is propitious to the fitting process of the spectral data. In particular，the giant noise in the strong interfered signal is de-noised，so that the signal can show the speed characteristics of the air flow which can perform the following step of lineshape fitting.

Key words: Wavelet analysis；Direct Absorption Spectroscopy；TDLAS；Noise cancellation；Distributed feedback diode laser