GPS虛擬衛星運作效益評估

Evaluations of the Effectiveness for GPS Pseudolite …..Fang-Shii Ning, Szu-Pyng Kao, Chia-Chyang

GPS定位技術是目前廣為使用的定位方法，然而GPS衛星也存在有透空不良造成無法精確定位之缺點。虛擬衛星為一個可傳播類似GPS信號之地面發射器，其可提供額外之觀測量，對於遮蔽區域之GPS定位應有助益，並可望提昇GPS定位精度並強化該系統的涵蓋面與妥善率。本研究成果已初步證實，GPS虛擬衛星之設置可使垂直坐標分量成果之重複性由2cm提昇為1cm，尤其是本研究進行作業之測試區並未有任何觀測空域之障礙，仍能在垂直坐標成果精度上取得大幅度之改善，顯見未來GPS虛擬衛星當可在有障礙觀測空間（如都會區之地籍測量）應用上，具有一定程度之發展潛能。 In recently, GPS technique has become a powerful positioning and navigation tool. However, there are still some drawbacks to GPS, such as the view of sky obstructed, causing the positioning accuracy degraded. The pseudolite, a satellite-like GPS ground signal generator, is then expected to provide extra-measurements and improve the GPS accuracy, coverage, and availability at the obstructed areas. It has been preliminarily proved by this study that the operation of GPS pseudolite can improve the repeatability of vertical component from 2 cm to 1 cm. It is encouraged that a level of 50% improvement can even be achieved at a test area without any obstruction to the view of sky. There is potential to practically upgrade the GPS effectiveness, especially for cadastral surveys carried on urban canyon, by using GPS pseudolite.

In recently, GPS technique has become a powerful positioning and navigation tool. However, there are still some drawbacks to GPS, such as the view of sky obstructed, causing the positioning accuracy degraded. The pseudolite, a satellite-like GPS ground signal generator, is then expected to provide extra-measurements and improve the GPS accuracy, coverage, and availability at the obstructed areas. It has been preliminarily proved by this study that the operation of GPS pseudolite can improve the repeatability of vertical component from 2 cm to 1 cm. It is encouraged that a level of 50% improvement can even be achieved at a test area without any obstruction to the view of sky. There is potential to practically upgrade the GPS effectiveness, especially for cadastral surveys carried on urban canyon, by using GPS pseudolite.