GPS/VRS positioning using atmospheric modeling

Real-time dense GNSS (Global Navigation Satellite System) networks have recently become available in many countries. They allow centimeter-level positioning accuracy using a network-based strategy. When such networks are unavailable, alternative methods are needed to achieve accurate positioning. We present an alternative approach implemented in Brazil to realize network-based positioning and the VRS (Virtual Reference Station) concept. We do not resolve integer ambiguities between reference stations but derive the network corrections from external atmospheric models. The method was tested using the So Paulo State Network of Brazil, where the reference stations are about 200 km apart. Accuracy on the level of decimeters was achieved, which is suitable for many applications in Brazil. The description of the method, results and an analysis is presented. (AU)