Problems in Ultra-High Precision GPS Position Estimation

We discuss the various techniques used to resolve integer ambiguities inherent in the measurements of GPS phase pseudoranges. In particular we formulate the problem as a mixed integer program and apply the CPLEX optimization software to simultaneously nd integer ambiguities and estimate relative position. The eeect of the Doppler shift is studied and a more general model for phase pseudoranges is presented. Finally, we study a two dimensional model for testing ambiguity resolution strategies, and discuss optimal satellite selection strategies.