| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 95 === With the rapid development and maturity in technology, Global Positioning System (GPS) has been widely used in navigation and positioning systems. One issue in GPS positioning is the lack of positioning accuracy information and people may use the GPS fix without any idea of its quality. In this thesis, the standard GPS NMEA output format is being used to determine the accuracy of the positioning and the information can then be provided to other applications or users. The Speed over Ground (SOG) and Course over Ground (COG) measured by the GPS are compared with the outputs from an accelerometer and a compass respectively. Based on the compared results, the characteristics of the GPS under the influence of the shadowing and multi-path effects of the environment are investigated. Four most important factors, including the average C/No values of the satellites with an elevation angle which is more than 40 degrees, the stability of SOG, the centripetal acceleration derived from COG and Position Dilution of Precision (PDOP) can be used to describe the GPS characteristics in these environments. Finally, a Fuzzy Logic based algorithm is proposed to determine the reliability and quality of the GPS fixes.
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