在現有衛星導航系統中，GPS已漸漸成為最為廣泛使用的系統，也是目前最成熟的系統。要使GPS接收器能夠提供定位服務須先花費30秒從衛星下載導航所需資訊，若想下載完整導航訊息(Broadcast Ephemeris and Satellite Almanac)則需花費將近12.5分鐘，導航訊息的具備與否，直接關係著GPS接收器第一次定位所需時間。
本研究利用Batch Processing與觀測量偏微分模型，將國際衛星導航服務組織(IGS)提供的精密星曆SP3三狀態參數格式，轉換成典型接收器可使用的廣播星曆15個軌道參數格式，並將衛星位置平均誤差從3公尺降至0.2公尺內；並利用廣播星曆各參數的相關長週期特性，配合傅立葉級數進行曲線擬合估測出未來1~7天的廣播星曆參數以取代精度較差的粗估星曆(Almanac)，將位置平均誤差的3~5公里降至300公尺內。應用於導航中可令使用者提前數小時接收精確型廣播星曆，有效縮短接收器首次定位時間，提高使用者定位效率。

Among present satellite navigation systems, Global Positioning System (GPS) becomes the most popular and mature system. GPS receiver usually takes 30 seconds to download the Navigation message in order to provide location-based services. But if we want to download the Navigation message which contains broadcast ephemeris and satellite almanac, it will take 12.5 minutes. Navigation message of GPS satellite equipped receiver to improve the time to first fix (TTFF).
Since the Standard Product three (SP3) Orbit format of the International Global Navigation Satellite System Service (IGS) precise ephemeris is with three state parameters and cannot be used by a conventional receiver, one of the main goals in this study is to design a batch processing algorithm so that a predicted SP3 ephemeris can be converted into a broadcast ephemeris format of fifteen orbit parameters. In this research, the average error of the satellite position can be decreased from three meters to 0.2 meters. The second goal of this study is to develop the prediction of broadcast ephemeris for the users that cannot daily update their ephemeris. In order to replace the almanac which has less precision, a curve fitting for a long period orbit parameter with Fourier series to predict GPS satellite orbit for next seven days has been executed. The average error of the orbit estimation from three to five kilometer can be reduced to less than 300 meters. Users can download this predicted ephemeris several hours before they go outdoors. Predicted ephemeris could decrease TTFF and increase the positioning efficiency.

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