Alternative Postprocessing Relative Positioning Approach Based on Precise Point Positioning

Abstract

A method for postmission relative positioning by global positioning system based on precise point positioning is presented as an alternative to the traditional double-differencing single-baseline approach. In this method, precise orbits and clock corrections are used at the reference station to estimate corrections to the ionospheric and wet tropospheric errors. For short reference-to-user ranges, these corrections are applied at the rover receiver in addition to the same precise orbits and clock corrections used at the reference to estimate the rover position. For relatively longer distances, a linear combination of dual-frequency measurements is used to eliminate the ionosphere and a residual wet tropospheric parameter is solved for as an additional unknown. The differential initial phase biases can be estimated as a residual ambiguity term, or calibrated from data of reference station network. The proposed approach has significant operational advantages over the traditional single-baseline positioning. The methodology of the proposed method is presented and discussed. To evaluate its performance, land and marine tests were conducted where the rover data were referenced, first using a reference station at a short distance, and second using another station at relatively longer distance. Results show that an accuracy of a few centimeters to subdecimeter level was obtained.