Development of Real-Time Software GPS Receiver using Windows Visual C++ and USB RF Front-end

Sanghoon Jeon, Hyoungmin So, Heekwon No, Taikjin Lee, Changdon Kee

Abstract:	This paper contains the research about the development of real-time PC-based software GPS receiver. CPU in general purpose computer is able to deal with larger data processing than FPGA (Field-Programmable Gate Array) or DSP (Digital signal processor) and provides more comfortable debugging environment of commercial development tools than that of embedded system. It is also flexible for new GNSS signal policy and for development of sensor integration system. IF (Intermediate Frequency) data is collected from SiGe USB RF Front end - GN3S v2. The software receiver is developed using Visual C++ 2008 program tool on Windows XP. For reducing redundant works, Intel Math Kernel Library for FFT calculation and MFC (Microsoft Foundation Class library) for multi-threads and data management scheme are used. In addition, GNU GPL (General Public License) USB library is used for USB hardware control. The real time software GPS receiver is composed of three threads which are USB control thread, GUI (Graphic User Interface) & display of receiver status thread and signal processing control thread. USB Data Control thread contains USB configuration, data stream control and saving down-converted IF data stream to data buffer. GUI thread contains displaying receiver status and receiving user command. In signal processing thread, whole stages of signal processing including acquisition, tracking, and navigation are implemented. Correlator in this thread especially needs lots of computation because of mass baseband data (16.376Mbps) from USB RF sampler. To reduce repetitive computation, in-phase and quadrature phase correlations and accumulations are computed by bit-wise parallel techniques and 16 bit sum table. In the same vein, saved code/carrier replica tables are used for replacing replica generator. This software has been tested using GPS live data from roof-mounted antenna with two commercial receivers. Test has been accomplished in 30 minutes and the positioning result of software receiver is similar distribution compared with that of commercial receivers.
Published in:	Proceedings of the 2010 International Technical Meeting of The Institute of Navigation January 25 - 27, 2010 Catamaran Resort Hotel San Diego, CA
Pages:	713 - 721
Cite this article:	Jeon, Sanghoon, So, Hyoungmin, No, Heekwon, Lee, Taikjin, Kee, Changdon, "Development of Real-Time Software GPS Receiver using Windows Visual C++ and USB RF Front-end," Proceedings of the 2010 International Technical Meeting of The Institute of Navigation, San Diego, CA, January 2010, pp. 713-721.
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