全球衛星導航系統(Global Navigation Satellite System，GNSS)能提供全天候與多用途的導航與定位服務，同時也是高精度的時間標準。隨著陸、海、空域之載具助導航及其他應用的日漸增加，各類使用者對定位系統的精確性(accuracy)、完整性(integrity)、可用性(availability)以及連續性(continuity)的要求也相對提升。在世界各國與相關組織皆已積極著手研發全球定位系統之星基增強系統(Satellite Based Augmentation System，SBAS)的趨勢，例如美國的Wide Area Augmentation System (WAAS)、日本的MTSAT Satellite based Augmentation System (MSAS)、歐盟的European Geostationary Navigation Overlay Service (EGNOS)、中國大陸的北斗或是印度的GPS Aided Geo Augmented Navigation (GAGAN)等廣域增強系統，其中，WAAS，MSAS和EGNOS都已經獲得適航認證提供民航導航服務，目前都已逐漸成為未來世界主要海陸空載具之標準助導航設備。因此，中國大陸，印度，俄羅斯與巴西等國都積極發展該系統。
為了更進一步掌握台灣地區廣域性(wide area)的完整性監測，本論文利用全球定位系統(Global Positioning System，GPS)之衛星訊號，進行研究和發展廣域差分定位系統(Wide Area Differential GNSS，WADGNSS)之主控站演算法，提升全球衛星導航系統服務之精確性、完整性與可用性。本廣域差分定位系統由三個主要的元件組成，即一個主站、多個參考站，以及廣域差分定位系統使用者端設備。本論文將使用由內政部國土測繪中心所研發之e-GPS 衛星基準站做為參考站，這些e-GPS 衛星基準站最初是為測繪目的而設計而成，故以現有e-GPS即時動態定位系統架構及功能為基礎，利用廣域差分定位系統提升全球衛星導航系統服務，確保運用本系統服務資訊之使用者安全，並進一步提供具有導航完整性之系統。
本篇論文將針對主控站處理程序進行研究，並驗證各步驟之結果，最後本論文在廣域差分定位系統所提供之電離層模型上，將算出之誤差修正量套用在各參考站上，以比較在台灣地區單純使用全球衛星導航系統之定位結果與使用廣域差分定位系統所提供之修正量之定位結果的效能增進。

To provide enhanced Global Navigation Satellite System (GNSS) service in Taiwan, a Satellite Based Augmentation System (SBAS) prototype, a Wide Area Differential GNSS (WADGNSS), is developed and tested in this work. There are several operational SBASs around the world, for example, the Wide Area Augmentation System (WAAS) in the United States, the MTSAT Satellite based Augmentation System (MSAS) in Japan, and the European Geostationary Navigation Overlay Service (EGNOS) in Europe. All of them were investigated and analyzed for many years before the implementation of the operational systems. In order to facilitate the implementation and operation of the SBAS and to evaluate its services to support land and maritime transportation services in Taiwan, the National Land Surveying and Mapping Center (NLSC) and National Cheng Kung University (NCKU) worked together to develop a WADGNSS. There are three major components of a WADGNSS, namely one Test-bed Master Station (TMS), several L1-L2 dual-frequency Test-bed Reference Stations (TRSs), and the WADGNSS user equipment. This thesis focuses on the development and validation of the TMS process. In this work, e-GPS satellite tracking stations, which have been developed and are operated by the NLSC, will be used as the TRSs. There are more than 80 e-GPS satellite tracking stations geographically distributed over the island of Taiwan. These e-GPS satellite tracking stations were originally designed for surveying and mapping purposes; therefore, the difficulties and challenges related to their use as WADGNSS TRSs is investigated. Detailed developmental steps for the TMSs and their validation testing are discussed in this thesis as well. Finally, the performance of the developed WADGNSS ionospheric delay model is presented by comparing the positioning results between using both a standalone GPS measurement and a GPS measurement with the WADGNSS ionospheric delay correction. As shown in the results, the positioning performance of GPSs in Taiwan can be enhanced by applying WADGNSS correction messages.

[1] Enge, P., Global Positioning System: Signals, Measurements, and Performance, Ganga-Jamuna Press, Lincoln, 2001.
[2] Parkinson, B.W. and Spilker J.J., Global Positioning System: Theory and Application, American Institute of Aeronautics and Astronautics, 1996.
[3] Jan, S.S., Aircraft Landing Using a Modernized Global Positioning System and the Wide Area Augmentation System, Department of Aeronautics and Astronautics Thesis, Stanford University, 2003.
[4] Enge, P., Walter, T., Pullen, S., Kee, C., Chao, Y.C. and Tasi, Y.C., “Wide Area Augmentation of the Global Positioning System” Proceedings of the IEEE, 1996.
[5] Chen, C.H., GPS Performance Assessment of a Local Area Monitoring System in Taiwan Region, Department of Aeronautics and Astronautics Thesis, National Cheng Kung University, 2008.
[6] Lu, S.C., Implementation of the Wide Area Differential GPS Master Station Algorithms in Taiwan Region, Department of Aeronautics and Astronautics Thesis, National Cheng Kung University, 2010.
[7] Chao, Y. C., Real Time Implementation of the Wide Area Augmentation System for the Global Position System with an Emphasis on Ionospheric Modeling, Department of Aeronautics and Astronautics Thesis, Stanford University, 1997.
[8] WAAS MOPS (Minimum Operational Performance Standards for global positioning system/ Wide Area Augmentation System airborne equipment), RTCA/DO-229D
[9] Chao, Y.C., Tsai, Y.J., Walter, T., and Kee, C., “The Ionospheric Delay Model Improvement for the Stanford WAAS Network,” Proceedings of ION National Technical Meeting 95, Anaheim, California, Jan. 1995.
[10] Saastamoinen, J., Contributions to the theory of atmospheric refraction, In three parts: Bulletin Géodésique, 1973, No. 105, pp. 270-298; No. 106, pp. 383- 397; No. 107, pp. 13-34.
[11] Black, H.D., “An Easily Implemented Algorithm for the Tropospheric Range Correction,” Journal of Geophysical Research, Vol. 83, No. B4, April 1978.
[12] Hatch, R.R., “The Synergism of GPS Code and Carrier Measurements,” Proceedings of the Third Geodetic Symposium on Satellite Doppler Positioning, Las Crues, NM, Feb 1982, pp123-1232.
[13] Sanders, M.A., “Characteristic function of the central chi-square distribution,” Retrieved, 2009
[14] Press, William H., Saul A., Teukolsky, William T. Vetterling, and Brian, P. Flannery, Numerical Recipes in C: The Art of Scientific Computing, Cambridge University Press, 1992.
[15] Kee, C., Wide Area Differential GPS (WADGPS), Department of Aeronautics and Astronautics Thesis, Stanford University, 1993.
[16] Schempp, T., Burke, J., Rubin, A., “WAAS Benefits of GEO Ranging”, Proceedings of ION-GNSS 21st. International Technical Meeting, Savannah Georgia, Sept. 2008.
[17] Tsai, Y.J., Chao, Y.C., Walter, T., and Kee, C., “Evaluation of Orbit and Clock Models for Real-Time WAAS”, Proceedings of the National Technical Meeting, The Institute of Navigation, Anaheim, California, 1995.
[18] Tsai, Y.J., Wide Area Differential Operation of the Global Positioning System: Ephemeris and Clock Algorithms, Department of Aeronautics and Astronautics Thesis, Stanford University, 1999.
[19] Alvarado, F. L., “The Matrix Inversion Lemma,” The University of Wisconsin Madison, Wisconsin, 53706, USA, March 1999.
[20] Klobuchar, J.A., “Design and Characteristics of the GPS ionosphere Time Delay Algorithm for Single Frequency Users,” Proceeding of IEEE Position Location and Navigation Symposium, Las Vegas, NV, 1986.