Research Of Tracking Andacquisition Algorithm For GPS Software Receiver Based On FPGA

The Global Position System is a global, all-weather real-time continuous positioning system,with a new generation of satellite navigation and positioning system in a full range of land, seaand air three-dimensional real-time navigation and positioning functions. With the wideapplication of GPS, the demands of a real-time and more accuracy positioning system is asked.Therefore, the work for designing a more accurate and efficient positioning method becomesvery important. The GPS software receiver consists of RF front-end, baseband signal processing,and navigation solution. The tracking algorithm is part of the baseband algorithm, and is one ofthe key technologies of navigation and positioning.The design and implementation of tracking algorithms in which the GPS Software Receiverbased on FPGA works are accomplished in this article. Firstly, a detailed introduction is given onthe basic principles of tracking algorithms, the settings of key parameters were done, includingthe bandwith noise of tracking algorithms, the loop gain, the range of fast catching and theparameters on loop filter. Then, the designing of FPGA on each module in the GPS trackingsystem is accomplished. In this thesis, the coded rings phase detector based on CORDICalgorithm which holds the advantages of high inaccuracy, simple structure and easy toimplement is designed. The optimization on the parameters of loop filter is done at the same time.Thus, the characteristic of real-time in tracking loop is improved greatly. Finally, the controlmodule is designed to coordinate the work of each sub-modules. The issue on real-time and themismatch of non-integer sampling frequency are well solved.The GPS tracking system designed in this thesis possesses the feature of fast locking,tracking and high accuracy. To download the acquisition and tracking system to the FPGAplatform, via the test of real-time data stream, the tracking system could correctly achieve thedemodulation of the navigation data. After the solution of navigation calculation module, thenavigation data demodulated can achieve the accuracy of positioning within meter level,simultaneously, the correctness of the design about the tracking system is proved.