摘要
基于可调谐半导体激光吸收光谱(TDLAS)的波长调制(WMS)技术是一种有效的痕量气体检测技术,具有高选择性、高精度、高灵敏度、实时在线监测等优点。现场测量过程中,背景噪音和光学条纹等的影响会严重降低系统的测量精度,影响浓度测量结果。为了有效消除这些噪音给测量带来的影响,提高系统信噪比(SNR),提出一种基于小波变换结合经验模态分解(EMD)的数字滤波降噪方法。对低质量浓度的NH3进行测量,分别采用小波变换滤波、经验模态分解滤波、小波变换结合经验模态分解滤波对获得的二次谐波信号进行降噪处理。实验结果表明,小波变换结合经验模态分解滤波相对于其他两种滤波方法效果最优,且对质量浓度为11.38 mg/m^(3)的NH_(3),信噪比由28.4 dB提高至446 dB,大大提高了系统测量精度。
Wavelength modulation signal(WMS)based on tunable diode laser absorption spectroscopy(TDLAS)is an effective trace gas detection technology.It offers several advantages such as high selectivity,high precision,and high sensitivity,as well as realtime online monitoring.In the field measurement process,background noise and optical fringes significantly reduce the system’s measurement accuracy,affecting the concentration measurement results.To effectively eliminate the effect of these noise on the measurement and improve the signal to noise ratio(SNR)of the system,this study proposes a digital filtering denoising method based on wavelet transform combined with empirical mode decomposition(EMD).The NH3 with low mass concentration was measured experimentally,and the wavelet transform filtering,EMD filtering,and wavelet transform combined with the EMD filtering were used to reduce noise in the obtained harmonic signals.The experimental results show that the wavelet transform combined with the EMD filtering has the best noise reduction effect compared to the other two methods.The SNR of the wavelet transform combined with the EMD filtering increases from 28.4 dB to 446 dB for NH_(3) with a mass concentration of 11.38 mg/m^(3).Thus,the proposed method significantly improves the system’s measurement accuracy.
作者
王璟
张立芳
杨巨生
杨艳霞
赵贯甲
Wang Jing;Zhang Lifang;Yang Jusheng;Yang Yanxia;Zhao Guanjia(Department of Thermal Engineering,College of Electrical and Power Engineering,Taiyuan University of Technology,Taiyuan 030024,Shanxi,China;The Postdoctoral Workstation of Taiyuan Boiler Group Co.,Ltd.,Taiyuan 030024,Shanxi,China)
出处
《激光与光电子学进展》
CSCD
北大核心
2022年第18期471-477,共7页
Laser & Optoelectronics Progress
基金
国家自然科学基金(51976132)。
关键词
可调谐半导体激光吸收光谱技术
小波变换
经验模态分解
降噪
tunable diode laser absorption spectroscopy
wavelet transform
empirical mode decomposition
noise reduction
