Abstract: Three representative precise point positioning (PPP) ambiguity fixing methods have been developed, which include the single-difference between-satellite method, the integer phase clock method and the decoupled clock method. Currently, only the French CNES published products applied to PPP ambiguity fixing using the integer phase clock method. Therefore, it is necessary to study the client PPP ambiguity fixing model based on integer phase clock method. This paper analyzes PPP ambiguity fixing model based on the integer phase clock method, and highlights the difference between the ambiguity-fixed PPP model and the traditional ambiguity-float PPP model. A cascaded ambiguity fixing strategy is proposed to perform PPP ambiguity fixing with special regard to quality control. Numerous kinematic PPP experiments show that ambiguity-fixed PPP can obtain a fast convergence, a better and stability positioning accuracy, compared with ambiguity-float PPP.

Key words: precise point positioning(PPP), integer phase clock method, ambiguity fixing, cascaded ambiguity fixing strategy