No abstract

Recent advances in wide-area differential GPS and dual-frequency receiver technology have made dramatic accuracy improvements feasible for Precise Positioning Service (PPS) users. Through a set of distinct upgrades to the GPS control segment, signal-in-space (SIS) accurac,y can be reduced to well under 1 m. Combined with optional user equipment upgrades, SIS error reduction makes submeter positioning accuracy achievable without the additional data link and reference receiver(s) generally required for differential systems.This paper focuses on the effectiveness of several SIS accuracy enhancement concepts. Results of parametric satellite monitoring experiments are used to divide control segment enhancements into subcategories based upon satellite monitoring accuracy and drift error characteristics.This parametric approach provides a framework for further comparisons of the various complementary and competing concepts under consideration. User-related errors such as multipath and atmospheric delays are also discussed to place SIS accuracy in the context of the overall PPS system.