Design Of Detection System Based On Surface Acoustic Wave Gas Sensor

Gas detection technology has a profound impact on human societies, especially in military fields, industry and daily life. Surface acoustic wave devices, which are widely used in military and commercial equipments, have an overwhelming superiority in gas detection. In the dissertation, a gas detection system based on SAW devices was investigated. The main work includes two sections: front-end and back-end.For the front-end system, the core circuit design based on dsPIC, thermostat, peripheral circuits which consists of power supply module, display module and pneumatic driving module were studied. Based on the investigation of hardware, the front-end program for acquisition of signal of SAW sensors and front-end control was designed. The reliability of hardware and software was tested. Moreover, the response of sensors was investigated as a function of gas density, velocity of flow and temperature, etc.For the back-end system, the clock module, reset module, dynamic memory module, storage module and peripheral circuits consisting of power supply module, display module, uart module and digital temperature sensor module were studied. Based on the investigation of hardware, the back-end program including transportation of Uboot, Linux and YAFFS2 file system, interaction interface, BP neural network algorithm and drawing algorithm was designed. Then, the reliability of hardware and software was tested and the result of recognition was analyzed.Based on the study of hardware, software and related algorithms system in the detection systems of integrated gas sensors, a reliable PCB circuit was made to validate the hardware, software and concerned algorithm. The above researches are beneficial for the development of practical detection system based on SAW gas sensors.