GPS Intermediate Signals Processing And The Implementation On FPGA

A GPS intermediate signals processing project is proposed in this paper. GP2015 RF front-end chip and FPGA are used in the hardware implementation to realize the algorithms of GPS. GP2015 which is produced by Zarlink Company is used to receive the intermediate signals, while FPGA to set up the hardware system and realize the algorithms.Firstly, the RF front-end and LVDS circuits are designed, and VHDL code is written to build the FPGA firmware. So the GPS intermediate signals could be received, transferred and stored in PC. Then, the graphic user interface written in c++ could be used for the control and test purpose. Based on these two sections, a GPS intermediate signals processing system which is convinent to do research in GPS is implemented.Acquisition and tracking are the two most complex and time consuming fuctions of GPS, so a fast and accurate acquisition method is brought forward in this paper. After comparing to the serial acquisition method through detail discussions, the frequency differential algorithm is proved to be adapted to find fine frequency of GPS intermediate signals.