Design And Implementation Of The Software-Defined GPS Receiver

A software-defined GPS receiver design and development is presented in this thesis, based on the technical approach using GPS IF data collector associated with PC-based positioning software. The research focuses on GPS baseband signal processing algorithms analysis and implementation. Upon software radio receiver concept, GPS baseband real-time signal processing and navigation computation is totally implemented by PC-based software, which makes GPS receiver more application flexible and lower product cost.In the starting chapters of this thesis, GPS system overview, GPS receiver types and applications are introduced. Following this, the detailed design of GPS IF data collector is provided, including hardware and embedded firmware design, as well as the related driver development. In the rest chapters, the thesis content covers GPS signal acquisition, GPS signal tracking, GPS navigation data demodulation, and receiver position calculation using least squares approach upon the pseudo-range measurements. The receiver reconfiguration function and receiver product cost analysis are also discussed briefly.The GPS signal processing methods research is the core part of this thesis, specifically for GPS signal acquisition and tracking. In the associated chapters, a new modified fast GPS acquisition method using cyclic correlation is performed, based on the introduction of GPS acquisition principles and technical analysis about the performances and shortcomings of the conventional acquisition methods. The experimental test shows the enhanced GPS acquisition performance is reached by the application of this new method. For the signal tracking loop, the designed GPS receiver expatiates on C/A code phase tracking through Delay-locked-Loop (DLL), and carrier phase and frequency tracking through Frequency-locked-Loop (FLL) and Phase-Locked-Loop (PLL). The navigation data is demodulated once GPS signal is tracked. All programs of this software-defined GPS receiver design are written by VS2008 C/C++ language. The associated software design approaches and flow charts are proposed in this thesis.In the end of this thesis, the field experiments are introduced for the performance testing of the designed software-defined GPS receiver. Under the static positioning mode, the experimental results show that GPS positioning accuracy is satisfied with the performance requirement referring to a high accuracy GPS commercial receiver. Under the dynamic positioning mode, the good positioning accuracy can be reached for the open-sky environment. However, the worse positioning results may be presented in urban environment due to the lack of satellite in view or satellite signal obscuration by buildings. Furthermore, the functional and performance tests are done for GPS cold start, sensitivity, and position output rate. These performance parameters are demonstrated to be satisfied with design requirements.