烈嶼全球導航衛星系統反射訊號干涉潮位站選址與試測

Site Selection and Testing of the GNSS-Reflectometry Interferometric Tide Gauge Station in Lieyu

「全球導航衛星系統」（GNSS, Global Navigation Satellite System）由衛星發射訊號，藉以量測衛星至接收機天線相位中心之距離，由而以交弧法達成導航與定位之功能。在此一應用中，所使用的是直接訊號，亦即使用由衛星至天線之訊號。同時，接收機天線亦接收經由反射面而抵達天線的間接訊號。這些反射訊號通常稱為因「多路徑」效應而產生，影響天線位置的求解作業。但是，反射訊號可以用於計算反射面至接收機天線相位中心之距離。如果反射面是感潮的水面，則可以用於海水位之觀測，亦即達成潮位站之功能。因此，使用直接訊號與反射訊號干涉處理的方式，配合GNSS定位的功能，位置合適之GNSS連續追蹤站，可以成為潮位站設置方式的替代選項。本文記述於金門烈嶼設置以量測海水面高度為目的之地基式連續追蹤站，依其功能又稱為GNSS-IR（GNSS Interferometric Reflectometry，全球導航衛星系統反射訊號干涉技術）潮位站，之選址與試作。

The ''Global Navigation Satellite System'' (GNSS) transmits signals from satellites to measure the distance between the satellite and the phase center of the receiver antenna, thereby achieving navigation and positioning functions through the arc intersection method. In this application, the signal used is the direct signal, i.e., the signal transmitted directly from the satellite to the antenna. At the same time, the receiver antenna also receives indirect signals that arrive at the antenna via reflective surfaces. These reflected signals are commonly referred to as being caused by the ''multipath'' effect, which can hinder the process of determining the antenna's position.
However, reflected signals can be used to measure the distance between the reflective surface and the phase center of the receiver antenna. If the reflective surface is a tidal water surface, it can be utilized for observing sea levels, thereby functioning as a tide gauge. Therefore, by using an interference processing method with both direct and reflected signals, combined with GNSS positioning functions, GNSS continuous operating reference stations located in suitable positions can serve as an alternative option for tide gauge installations.
This article describes the site selection and experimental setup of a ground-based continuous operating station established on Lieyu, Kinmen, for the purpose of measuring sea surface height. Based on its function, it is also referred to as a GNSS-IR (GNSS Interferometric Reflectometry) tide station.