| Summary: | 碩士 === 國立交通大學 === 電機工程學系 === 102 === This thesis aims to develop a system of mixture gas measurement which uses single gas sensor to detect varied harmful gas in sewer. Measure mixture gas in the environment; meanwhile, use difference voltage in the heater of front sensor in order to change sensor’s temperature. Then, use algorithm to distinguish mixture gas for achieving qualitative and quantitative. For the environment, the system uses single gas sensor which is used to detect varied mixture gas to complete all analysis. For the approach of changing sensor’s temperature, the thesis proposes two methods. First, when it has a reaction between sensor and gas, use two difference voltage in the heater separately to make the reaction steady both times. It is known as static state modulate. Second, when it has a reaction between sensor and gas, constantly vary voltage’s state and time in the heater to show a square wave of period. It is known as dynamic state modulate. The above-mentioned methods make that front sensor do not need to use multi-sensors to form array, single process do not need an additional algorithm to feature extraction and pattern recognition, and the application of system can be easier in single process in time domain. Besides viability of analysis method after measurement, also verify this method on MCU to achieve real time analysis and display purpose.
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