The Research And Implementation Of Photoacoustic Spectroscopy Gas Sensor Based On LED Source

Based on the limitation of the sensitivity of the traditional gas detection device,it is difficult to detect the trace gas effectively,present a idea that using photoacoustic spectroscopy technology to detect instead of Poisonous gas detection device.The LED light source is used to replace the conventional photoacoustic spectrum laser,which greatly improves the measurement accuracy.As the infrared absorption band of the LED light source is so wider that could causing the phenomenon of infrared absorption overlap,so blind signal separation method is used to process the collected signals.The paper mainly built microphone photoacoustic detection platform by using high quality characteristics of the quartz tuning fork and equipped with resonance tube.Firstly,the photoacoustic spectroscopy technology is introduced briefly.mainly about Absorption of infrared light,principle of photoacoustic signal,detection method and effect of quartz tuning fork correlation characteristics of system is introduced.Secondly,the blind signal separation method is introduced.Mainly related to the basis of Mathematics,Building model and then a depth study of the improved FastICA method is carried out.In this paper,the double precision calculation method is designed,and the improved blind signal separation algorithm is combined with the double precision calculation.Thirdly designing Software and hardware of detection system..The ARM control module is implemented by writing program under the platform of visual studio2008 and designing related application interface.Due to the limitation problem of calculation accuracy,designing a structure which can Improve it and putting the improved blind signal separation algorithm combined with the 64 bit symbol library into Embedded platform to run.Finally,useing CO2 as the target gas to measure the photoacoustic signal and gas concentration and separate CO2 and SO2 by the processing of improved blind signal separation algorithm.The experimental results show that it is feasible to use blind signal separation algorithm to separate mixture signal and the designing of experimental platform has the characteristics of high detection speed and high precision.