A Multi-Constellation Real-Time SSR Service for PPP-AR Based on GDGPS Orbit Determination

A service to enable Precise Point Positioning with Ambiguity Resolution (PPP-AR) through a standard zero-difference State Space Representation (SSR) formalism has been implemented at JPL/NASA's Global Differential GPS System (GDGPS). The supported constellations are GPS, Galileo and Beidou, with carrier phase frequencies L1+L2 for GPS, E1+E5b for GAL, B1I+B2I for BDS-2, and B1I+B2a for BDS-3 (traditional names). The JPL/GDGPS service is based on real-time GDGPS orbit determination with estimation of biases and ancillary parameters, using a global network of over 100 1-Hz real-time high-precision GNSS receivers. Extensions of the JPL GCORE software suite to produce the SSR parameters are described. The connection between the Wide-Lane/Phase-Bias (WLPB) approach to PPP-AR developed at JPL is described. In addition, the relationship with other (widely available) styles of SSR service is clarified. Accuracy of positioning is investigated globally and found to be comparable with traditional high-precision geodetic post-processing techniques. The advantages of processing multiple constellations are quantified. Time-to-fix is investigated using different strategies and available positioning clients. Finally, various applications of PPP with societal benefits are discussed for which the service has the potential to make a significant contribution, such as real-time monitoring of natural hazards, geodetic processes and space weather.