The Performance Analysis for Future GNSS in Taiwan Region

• Main Authors: Meng-Lun Tsai, 蔡孟倫
• Other Authors: Kai-Wei Chiang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/94222621585647736376

碩士 === 國立成功大學 === 測量及空間資訊學系碩博士班 === 96 === Global Navigation Satellite Systems (GNSS) can provide the positions of satellites, reference stations and user receivers globally. It will have significant impact on the development of surveying and mapping technologies. Based on the compatibility of the navigation signals between modernized Global Positioning system (GPS) and Galileo, this study aims at exploiting the performances of each system and GPS/Galileo integrated system in Taiwan region, respectively. Therefore, a GNSS software simulator is developed in this study. The performance indices satellite visibility, dilution of precision (DOP) values and reliability are analyzed in terms of their temporal variations, spatial variations and sensitivities to signal obstruction. The correctness of simulated GNSS measurements used for further relay on the systematic error models of GNSS implemented in the software simulator. Therefore, the error models including ionospheric and tropospheric delays as well as orbital errors are investigated to fit the scope of Taiwan region. Given the positions of GNSS satellites and user, the simulated pseudoranges and carrier phase measurements can be obtained with the addition GNSS systematic error models and integer ambiguity for further use. The preliminary results presented in this sutdy indicate the improvement for the GPS/Galileo integrated constellation in terms of the visible satellites in comparison with GPS or Galileo individually. In addition, the averaged DOP values and reliability of the dual system are improved for the standalone GPS and Galileo scenario. Most importantly, using GPS/Galileo system provides sufficient availability for positioning in extreme masking environment, where positioning with GPS or Galileo is currently very difficult. Consequently, all the performance indices given in this study strongly indicate the benefits of future GPS/Galileo integrated positioning. On the other hand, the remaining issues concerning the compatibility and interoperability between GPS and Galileo should be investigated continuously to develop effective algorithms accommodating their measurements in the future study.