軟體GPS接收機的演算法架構與模擬

Abstract

近年來通訊技術的進步，使得全球定位系統(Global Positioning System)的應用日益廣泛，GPS產品大多應用於航空、航海、車用等交通方面，一般商用GPS有使用環境的限制，操作環境必須在高度18000公尺以下、速度不能超過515公尺/秒、加速度須在4g以下，另外一般商用GPS硬體條件、軟體架構已固定，綜合以上因素，高動態環境下(如：探空火箭)的定位不適合使用一般商用GPS；相較之下，軟體GPS的可程式性，通過更新軟體程式就可改變演算法架構，因此本論文選擇軟體GPS接收機為研究的平台。 本論文以MATLAB模擬非即時架構的軟體GPS接收機演算法流程，包含：訊號擷取、訊號追蹤、解碼導航訊息、計算用戶位置，並以國家太空中心提供的GPS訊號來驗證演算法效能和可用性，最後研擬軟體GPS即時架構的流程圖。

The improvement of communication technology made GPS (Global Positioning System) widely used in recent years. GPS products are often applied to navigation systems including aviations, marines, and automobiles. In general, commercial GPS are used in the environment that the altitude of the receiver is less than 18000m/s, speed and acceleration are less than 515m/s and 4g, respectively. Limited by above factors, commercial GPS can not be applied to high dynamic positioning. Compare to commercial GPS, the programmability of software GPS can change the algorithm structure through updating software. Therefore, the software GPS is selected as a platform in this research. In this thesis, we use MATLAB to simulate a non real-time algorithm of software GPS, which includes “acquisition,” “tracking,” decoding message data, and calculating user position. This algorithm is verified by the GPS data provided by National Space Organization (NSPO). Lastly, we propose a signal processing flow for the real-time software GPS.