| Summary: | 碩士 === 國立東華大學 === 電機工程學系 === 99 === The variation of fog concentration in the atmosphere plays a very important role to the safety of road traffic, aircraft navigation and maritime transport. It affects not only to human beings but also to the growth of plants in the nature. In this thesis we construct a fog sensor system with the structure of forward scattering by using LED and photodiode for the application of monitor the variation of fog concentration in the atmosphere.
Inside the fog sensor, it has a band pass filter to reduce the interference of background light source on photodiode, and a compensation circuit composed of a negative coefficient thermistor and operation amplifiers is also included to overcome the temperature effect on optoelectronic components.
Finally we test the performance of this fog sensor in high altitudethe area, Chi-Lan Mt. According to the results measured, the fog sensor has maximum 370mV output variation range corresponds to 21.3% attenuation and can be used to monitor the variation of for concentration in the atmosphere.
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