GNSS訊號擷取程序將處理更多的衛星訊號，因為未來將有更多的衛星導航系統建置。因此，首次定位時間將成為未來GNSS接收機的重要效能因子，目前有許多學者提出使用組合電碼的方式來降低訊號擷取程序的運算量，本文針對其中兩種組合電碼擷取方法進行效能評估與分析：第一種是作者提出的多重電碼擷取方法，第二種為Beach所提出的擷取方法。效能分析的項目包括：發現機率，正確擷取機率，平均擷取時間和加速因子。本文撰寫C++程式以進行各種架構下訊號擷取效能分析，本文GPS訊號來源為利用軟體接收機放置於成大航太系頂樓收集之真實中頻訊號，因此，本文中之各項效能分析皆是以真實採集的GPS中頻訊號來進行估測與驗證。
The GNSS acquisition process will need to acquire more signals transmitted by many satellite systems when more satellite systems are developed and operated. Therefore, the Time to First Fix (TTFF) of the GNSS receiver becomes a very important factor. One of the acquisition methods which are capable of reducing the computation load is the composite code acquisition method. Two composite PRN code acquisition methods are analyzed in this paper: the multi-C/A code acquisition method developed by authors and the Beach’s acquisition method. This paper evaluates both composite PRN code acquisition methods in terms of the probability of detection, the probability of correct acquisition, the mean acquisition time, and the Speedup factor. A C++ program is developed to assess the performance of the GPS signal acquisition under various architectures. The real GPS intermediate frequency (IF) signals collected by a software receiver at the roof of the Department of Aeronautics and Astronautics building of National Cheng Kung University are used in this paper. As a result, the probabilities of correct acquisition, the mean acquisition time, and the Speedup factors of both acquisition methods are estimated and validated using the collected IF signal data.
