Improving ambiguity convergence in carrier phase-based precise point positioning

This thesis describes the research results in the improvement of a new GPS processing approach: precise point positioning (PPP). Currently, PPP is implemented with the so-called Traditional Model based on the un-differenced dual frequency code and carrier phase observations aided by the precise satellite orbit and clock products. Decimetre to centimetre accuracy is achievable while an average of half an hour of convergence time is required. In order for the PPP system to be used in real-time positioning and navigation applications, accelerating ambiguity convergence therefore is essential for a fast positioning convergence solution. With the newly developed code-phase ionosphere-free combination in this research, an alternative PPP processing method---P1-P2-CP Model---is proposed, which has a lower measurement noise and a smaller residual error. But the biggest gain of the P1-P2-CP Model is the feasibility of the fixed ambiguity resolution which brings fewer unknowns, therefore accelerating solution convergence. In the model's implementation, a variance adjustment procedure was applied to obtain more precise stochastic information of both observations and parameters, and a partial ambiguity searching and fixing approach based on a pseudo-fixing concept was preliminarily developed. Included in this thesis are the numerical results and analyses of float solutions in both static and kinematics processing. Fixed solution results in static processing mode are also presented. Further considerations for the improvements of the convergence performance are also addressed.