Performance Analysis of Precise Point Positioning Using Rea-Time Orbit and Clock Products

Abstract

The real-time availability of precise GPS satellite orbit and clock products has enabled the development of a novel positioning methodology known as precise point positioning (PPP). Based on the processing of un-differenced pseudorange and carrier phase observations from a single GPS receiver, positioning solutions with centimeter to decimeter accuracy can be attained globally. Such accuracy can currently be achieved only through differential processing of observations acquired simultaneously from at least two receiver stations. The potential impact of PPP on the positioning community is expected to be significant. It brings not only great flexibility to field operations but also reduces labor and equipment cost and simplifies operational logistics by eliminating the need for base stations. This paper will address issues related to precise point positioning and perform data analysis to assess the performance of different application solutions from PPP using real-time precise orbit and clock corrections. They include the discussion of an algorithm for un-differenced data processing, error source and mitigation, and critical elements related to real-time GPS orbit and clock products. Numerical results will be presented to show the positioning accuracy attained with datasets acquired from different environments using real-time precise orbit/clock products currently available. Features of a software package that has been developed at the University of Calgary for precise point positioning will also be described.