GPS軟體式接收器於DSP-FPGA平台上的實現

Abstract

在全球衛星定位系統中，需要接收衛星傳遞的訊號以做定位使用，由於在訊號傳遞時衛星與接收端會有相對運動，造成訊號的頻率偏移，另外，發射至接收訊號間會有時間差，也產生了訊號延遲的現象。因此想順利解讀出定位所需資訊，必須先找到準確的訊號頻率與其時間延遲，我們利用訊號擷取、訊號追蹤迴路來完成此工作。 本論文為了將程式能實現在單晶片上，首先分析傳統的訊號擷取，並在傳統的架構底下發展出減少運算量的方法，如此不僅能夠節省許多時間，也能夠更有效率的使用硬體。接著在將訊號送進訊號追蹤迴路前，因其迴路的頻寬不大，所以得先將頻率偏移誤差再更進一步的降低，為此，我們利用相關值的特性得到想要的頻率範圍。 本論文利用labview軟體編譯GPS訊號擷取、訊號追蹤之演算法，並利用分析出之系統架構將其分別編譯至單晶片不同的位置，以期將資源發揮到最大的效能，最後利用天線錄得的訊號來驗證演算法的效能與可用性，並比較傳統及新的方法得到結果之間的差異。

In Global Positioning Systems, we need to receive the signal transited by satellite for positioning. Because of the relative motion between satellite and receiver and transit time, it will cause the frequency shift and time-delay of the signal. We must lock the frequency and time-delay of the signal precisely for acquiring the information for positioning. So we need to reach the goal by using acquisition loop and tracking loop. In order to compile on the single board, we analyze the traditional signal acquisition first, and develop a method which can decrease the computation under the traditional framework; Therefore the method can not only save lots of time but utilize the software more efficiently. Because of the limit bandwidth of the loop, we have to lower the frequency offset error before we send the signal in to the signal tracking loop, and we use the feature of the correlation to gain the frequency we want.

In the paper, we use Labview to compile the algorithm of GPS signal acquisition and signal tracking, compiling the analyzed system structure in to different single board location, in order to maximize the effectiveness of the resources. Finally, using the signal recorded by antenna to verify the effectiveness and availability of algorithm, and then comparing the traditional method results with the new one.