精密單點定位-即時動態定位(Precise Point Positioning- Real Time Kinematic, PPP-RTK)為PPP與RTK結合，成為最新的衛星定位技術。PPP-RTK在其他國家已經成熟且運用於科技研究與工程實作等領域，如美國、歐洲、日本、澳大利亞等地區。PPP-RTK將PPP與網路RTK(Network RTK, NRTK)的優點結合，可以即時定位解算成果，獲得公分級定位精度。另外，NRTK與PPP-RTK兩者技術略有不同，重點在於NRTK使用觀測空間表示(Observation Space Representation, OSR)，PPP-RTK使用狀態空間表示(State Space Representation, SSR)，兩種不同方法提供GNSS校正服務。本研究在台灣測試PPP-RTK與NRTK的成果比對，總共有三天的資料。固定解的定位成果，PPP-RTK的固定解百分比為30.18%，NRTK的固定解百分比為99.80%。PPP-RTK之固定解RMS值為公分等級，NRTK之固定解 RMS值亦為公分等級，但是NRTK比PPP-RTK之固定解RMS值較低，因此NRTK仍然比PPP-RTK的定位性能好。另一方面，臺灣為中低緯度地區，觀測時間於春天4月至5月，電離層活躍較大。將電離層的TEC值分別對固定解百分比率與定位誤差RMS值做相關係數，得知NRTK定位成果與TEC值之間為低度線性相關，PPP-RTK定位成果與TEC值之間為中度線性相關。因此，電離層的TEC值多寡顯著影響PPP-RTK定位成果，尤其PPP-RTK定位在中午至下午無法收斂到固定解。本研究之PPP-RTK實驗成果與國外的PPP-RTK效能還有一段距離，未來期望PPP-RTK能夠進一步改善。

Precise Point Positioning - Real Time Kinematic (PPP-RTK) is a combination of PPP and RTK, making it the latest satellite positioning technology. PPP-RTK is well established and used in other countries, such as the USA, Europe, Japan, and Australia, for scientific research and engineering work. PPP-RTK combines the benefits of PPP and Network RTK (NRTK) to achieve centimeter-level positioning accuracy with real-time positioning resolution results. In addition, NRTK and PPP-RTK are slightly different techniques, highlighting the fact that NRTK uses Observation Space Representation (OSR) and PPP-RTK uses State Space Representation (SSR). The two different methods provide GNSS calibration services. In this study, the results of PPP-RTK and NRTK were tested in Taiwan for a total of three days of data. The overall percentage of fixed solutions for PPP-RTK was 30.18%, and the overall percentage of fixed solutions for NRTK was 99.80%. The overall fixed solution positioning results are on a centimeter-level for PPP-RTK and a centimeter-level for NRTK. However, NRTK still provides better positioning performance than PPP-RTK. On the other hand, Taiwan is low to the mid-latitude area, where the ionosphere is more dynamic during the spring months of April and May. As a result, the amount of TEC in the ionosphere affects the PPP-RTK positioning results, especially as PPP-RTK positioning does not converge to a fixed solution between noon and afternoon. This PPP-RTK experiment is still a long way from the performance of PPP-RTK abroad, and it is hoped that PPP-RTK will improve and become widespread in Taiwan in the future.

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