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題 名 | GPS天線相位中心率定及改正之研究=A Study on the Calibration and Correction of the GPS Antenna Phase Center |
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作 者 | 陳春盛; 陳怡兆; | 書刊名 | 測量工程 |
卷 期 | 41:3 1999.09[民88.09] |
頁 次 | 頁1-26 |
分類號 | 440.98 |
關鍵詞 | GPS天線相位中心; 全球定位系統; Global positioning system; |
語 文 | 中文(Chinese) |
中文摘要 | 以GPS進行點位量測時,觀測量是以天線相位中心為基準的,然而,天線相位中心 並非天線之物理中心,且相位中心是非固定的。 對於任一 GPS 天線,其相位中心會隨衛星 信號來源方向而改變,因此,GPS 天線相位中心變化是相當複雜的。另外,相位中心的變化 與天線型式是相關的,此種變化在混合不同型式天線同步觀測時應仔細考量修正。不同型式 天線之相位中心變化主要影響為 GPS 測站之相對高程, 其影響可達 10 公分(不論測站之 遠近)。即使使用同型天線,仍可能造成 0.015ppm 之尺度誤差。 GPS 天線相位中心偏移量及變化量可由實驗室法及實測 GPS 觀測法分別測定。 本研究將以 實測 GPS 觀測法來率定相位中心偏移量及變化量,此方法較實驗室法簡易, 而精度仍可達 到實驗室法的水準,但所獲得者為天線間之相對改正量,因此,至少需有一部天線(參考基 準)視為已知。 本研究將比較相位中心改正前後對 GPS 量測精度之影響,並建議一可行之 GPS 天線相位中 心率定模式,及相位中心改正模式。 |
英文摘要 | The precise point whose position is being measured from GPS is generally assumed to be the phase center of the GPS antenna. However, the phase center of a GPS antenna is neither a physical point nor a stable point. For any given GPS antenna, the phase center will change with the direction of the signal from a satellite. Therefore, the variation of the GPS antenna phase center is very complicated. Besides, the phase center variations are antenna-type-dependent. This effect has to be carefully modified when different types of antennas are used simultaneously. Ignoring these phase center variations can lead to serious (up to 10 cm) vertical errors that are independent on the baseline length. Even if the same types of antennas are used, the main effect is a scale factor up to about 0.015ppm. The antenna phase center offsets and it's variations may stem either from anechoic chamber measurements or from estimations using GPS data. This study will estimate the antenna phase center offsets and variations from GPS data. The effort for setting up such a campaign is considerably smaller than collecting the chamber measurements. The resulting accuracy is comparable with that of the chamber tests but the disadvantage is that only the relative corrections may be estimated. Therefore at least one reference antenna has to be introduced as known. We will compare the results of GPS measurements from phase center corrections and no corrections. And command a feasible method to calibrate antenna phase center and a correction model. |
本系統中英文摘要資訊取自各篇刊載內容。