本論文主要說明GPS反射訊號處理與地表高度整合應用GPS接收儀之設計與研發。在設計構想上，同時應用右弦圓柱型極化及左弦圓柱型極化天線分別接收GPS直接訊號及反射訊號，且進行反射能力分析及地表地物識別、土壤含水率、都卜勒位移測算水面流速應用研究 ；此特別之天線整合裝置設計，在無須提升天線接收靈敏度條件下，使左旋天線接受之頻寬、極化圓柱型頻束角度變大。依此方法應用地球幾何座標，各衛星與接收儀所在位置形成視距線上，接收多組GPS反射訊號推算出實際地面或水面反射點位置與高度。
本研究以近似單點定位解方式，使用衛星星曆程式初算衛星位置與衛星時間延遲量。並以整數未知數法則，應用GPS L1與L2相位觀測量之周波未定數項求解。再以雙頻相位觀測量推導大氣電離層修正量與對流層修正估測數模式，自動迭代即時大氣層再修正量後，精確收斂正、反接收儀座標解。在研究分析過程，為快速精確收斂算出所接收各組反射訊號之實際地面或水面反射點位置與高度，考量反射面粗糙度、反射角偏移、地表特徵影響。並結合數位地形高程資料庫，整合衛星影像圖之應用。可有效監控來自海面、陸地及河床表面實驗之多組反射點不同高程值，座標位置精確收斂至2公分至 10公分合理誤差。其中高程誤差來源主要為受到反射面粗糙度、反射角偏移影響達到5公分至30公分高程誤差。
本研究最重要之成果在於應用GPS反射訊號之相位觀測量，並透過偵獲反射訊號過程，以比對每一組GPS衛星直接訊號與反射訊號之相位觀測量，並計算出GPS反射訊號隨衛星所經過之地表之反射能力及對地表之特徵進行地物識別，例如：溪流緩流、溪流勁流、乾土壤、濕土壤、草地、林地、稞露表土及水泥道路等，特別在乾、濕土壤之含水率識別度，可分析出土壤表層之體積比例飽和含水率，同時應用戶外實驗室執行反射能力與土壤之粒徑成分實驗，建立GPS反射能力、土壤含水率、介電係數關係公式。本研究於實驗研究海面與溪流之水流觀測，使用地球自轉角動量修正模式，結合都卜勒頻率位移量之最小平方追尋法在ENU座標體系，測算水流速度，可計算如溪流洪水範圍達5公分/秒至 265公分/秒，精度達0.5公分/秒。

In the paper, Application and development of a highly integrated GPS receiver with reflected GPS signals for ground object detection, soil moisture, and stream flow will be described. Several application considerations have been analyzed in order to successfully acquire and track weak, reflected GPS signals from ground surface. First of all, both RHCP and LHCP antennas are employed so that direct and reflected signals can be acquired simultaneously. The direction of arrival of the signals may be along the reflected signal path or even along the line-of-sight of a particular satellite.
GPS Almanac data provided the initial satellite positions, clock error delay and atmospheric delay parameters. An integer ambiguity resolution algorithm has also been implemented. The precise point positions for RHCP and LHCP antennas are enhanced and processed by repeating instantaneous ionosphere delay correct model with deriving from L1 and L2 carrier phase and troposphere estimated parameter model. During the development and test stage, the DTED and visual elements of satellite’s images has been used and mapped with the integrated software. For sensing of ocean, landscape, and stream, due to rough surface effects and propagation angle effect on slanting surface, the accuracies of each reflected altitude are among 5 cm and 30 cm. The accuracies of each reflected area are converged among 2 cm and 10 cm.
Unlike most existing GPS reflection experiment, the goal of the study is to exploit the carrier phase, reflectivity of L1/L2 SNR components of the reflected signals and direct signals for stream clam water, disturbed water, dry soil, wet soil, grass, tree, bare soil and concrete road object detection with surface. The soil moisture for surface of soil should be classified by volumetric content of saturated water for soil.
In monitoring coastal tidal currents, water levels, and floodwater levels, the velocity vectors for flows speed of was estimated approximately among 5 cm/s and 265 cm/s by using differential carrier Doppler shifts and a coordinate rotation correction model. The accuracies of velocity were converged 0.5 cm/sec.

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