Assessment of Composite PRN Code Acquisition Methods for GPS Signal

摘要

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.