利用GPS反射信號推求水波波形之研究

A Study for Inquiring into Water Wave Patterns Using RGPS Technique

本研究主要是將全球衛星定位系統（Global Positioning System, GPS）之衛星接收儀與整合右旋與左旋圓極化天線，接收來自水面之衰弱GPS反射訊號，擷取並進行科學分析及應用研究，同時應用右旋圓極化及左旋圓極化天線分別接收GPS直接訊號及GPS反射訊號，並微調接收天線使其可分辨GPS正、反訊號，獲得天線有效接受之頻率範圍與更近似之方位，依此幾何方法，進一步利用各衛星與接收儀天線所在位置形成之投影，反推算所接收各組微弱反射訊號之虛擬地面或水面反射點。本研究之特點在於應用GPS反射訊號之相位觀測量，並透過擷取反射訊號過程中與直接訊號相位觀測量加以比對訊號強度、時間修正延遲量、大氣修正延遲量之修改與設計後，完成求解反射點位置與高程，再利用這些精確高程，推求波形模式，推算波浪特性與型態，提供河海與港灣工程以及潮汐觀測之用。

The purpose of this research is to develop a highly integrated GPS receiver with RHCP and LHCP antennas mounted on an iron-frame to receive direct and reflected GPS signals. In order to successfully acquire and track weak reflected GPS signals from ground and water-surface, there are several designs must be analyzed. First of all, both RHCP and LHCP antennas are employed and adjusted so that direct and reflected signals can be acquired. Then, the height of antennas foot print can be solved by analyzing the carrier phase of observation. During receiving GPS direct and reflected signals, by comparing intensity of signal, modifying time delay and atmospheric delay, the position and height of the reflected point of the signal can be solved. Since the locations of the reflected points are the surface of the water, the pattern of water wave can be determined. From determining the shape of water wave, the characteristic of wave can be figured out. It is the useful data for harbor engineering and oceanic tide observation.