台灣地區中長距離GPS動態定位成果與精度分析

Analyzing and Estimating of Medium-Range GPS Kinematic Positioning in the Taiwan Area

為了解台灣東部地區實施海底大地測量，可佈設海底音波回應器陣列位置與陸地的容許最遠距離為何；於2008年中，我們設計一個陸上GPS動態定位實驗。以中研院地球所六樓樓頂平台為實驗場地，旁邊8m範圍內有S101衛星固定站天線柱。結合野外測試場的動態測量資料，測試設計距離由11km至256km。與S101衛星固定站的動態成果比較，其整體的平均南北向較差為-6±23mm、東西向為-18±48 mm、高程向為21±73 mm。另於2008年10月及2009年3月，實際計算宜蘭東方約80 km 外海，及花蓮東方約100 km 外海的動態定位結果。經比較兩種動態定位軟體（Bernese V5.0 及GrafNav），宜蘭外海的較差在南北向為3±16 mm，東西向為8±22 mm，高程向為27±44 mm；而花蓮外海的較差在南北向的差異為-6±18 mm，東西向的差異為14±14 mm，高程向為35±28mm。由此實測資料可發現，南北向的較差略優於東西向，而高程向的較差小於4cm。 To understand the limitation distance of medium-range GPS kinematic positioning forthe sea-floor geodesy, an on-land experiment with relative distance from 8 m to 256 km, hasbeen conducted and two experiments off-Hualien with distance of 100 km and off-Ilan withdistance of 80 km have been conducted in October 2008 and March 2009. For the on-landkinematic GPS experiment, the true values are acquired from S101, one of the CORS near theexperiment field (only about 8 meters away). Results from other stations in the range of 11 kmto 256 km are compared with true values. The accuracies are 2±14 mm in the north-southcomponent, -28±33 mm in the east-west component and 7±43 mm in the up component.For the off-Ilan and off-Hualien experiments, the results are computed by BerneseV5.0 and GrafNav V8.0. The differences are 1±24 mm in the north-south component, 15±44 mm in the east-west component and 22±75 mm in the up component for the off-Ilan experiment, and -6±18 mm in the north-south component, 14±14 mm in theeast-west component and 35±28 mm in the up component for the off-Hualienexperiment, respectively. From the above experiences, the accuracy of north-southcomponent is better than east-west component, and the up component is less than 4cm.

To understand the limitation distance of medium-range GPS kinematic positioning forthe sea-floor geodesy, an on-land experiment with relative distance from 8 m to 256 km, hasbeen conducted and two experiments off-Hualien with distance of 100 km and off-Ilan withdistance of 80 km have been conducted in October 2008 and March 2009. For the on-landkinematic GPS experiment, the true values are acquired from S101, one of the CORS near theexperiment field (only about 8 meters away). Results from other stations in the range of 11 kmto 256 km are compared with true values. The accuracies are 2±14 mm in the north-southcomponent, -28±33 mm in the east-west component and 7±43 mm in the up component.For the off-Ilan and off-Hualien experiments, the results are computed by BerneseV5.0 and GrafNav V8.0. The differences are 1±24 mm in the north-south component,15±44 mm in the east-west component and 22±75 mm in the up component for the off-Ilan experiment, and -6±18 mm in the north-south component, 14±14 mm in theeast-west component and 35±28 mm in the up component for the off-Hualienexperiment, respectively. From the above experiences, the accuracy of north-southcomponent is better than east-west component, and the up component is less than 4cm.