光声池中微弱光声信号检测

大气中的污染源气体含量很少, 用光声光谱对其进行监测得到的光声信号极其微弱. 本文首先分析微弱信号产生机理, 在分析Holmes Duffing方程的基础上, 提出了适合光声池微弱信号检测的变尺度差分方法. 该方法通过对信号进行尺度变换, 再做差分来检测微弱信号. 理论分析和实验表明, 变尺度差分方法能很好地抑制系统相空间的共模噪声, 而且能很好地凸显混沌状态临界值. 变尺度差分方法测出的信号相对误差都小于5%, 说明其可以用于较高频率、 相位和频率都未知的微弱光声信号幅值检测.关键词：光声光谱微弱信号幅值Duffing

Weak photoacoustic signal detection in photoacoustic cell

The content of pollution gas in atmosphere is generally small, so the photoacoustic signal detected by photoacoustic spectroscopy to monitor is very weak. In this paper, on the basis of Holmes Duffing equation, we propose a new method i.e. variable scale difference method which is quite suitable for photoacoustic signal detection. This method can be used to detect weak signal by transforming the size of signal and then substracting the resulting signal. Theoretical analysis and experimental measurements show that it can well restrain the common-mode noise of system phase space, and it can also highlight the chaos state of critical value. This method has a relative error less than 5%, indicating that it can be effectively used to detect the amplitude of weak photoacoustic signal that has a higher frequency and unknown phase and frequency.
Keywords：photoacoustic cellweak signal detectionamplitudeduffing