NovAtel CORRECT with Precise Point Positioning (PPP): Recent Developments

Precision GNSS users are continuously pushing the technology for improvements in accuracy, operation in more challenging conditions, and the ability to keep working for extended periods of time. The availability of reliable, high quality position solutions to meet these ever increasing demands in variable applications is at the heart of NovAtel CORRECT™. There are a large number of applications, like those found in precision agriculture or mobile mapping, which benefit from globally available cm-level positioning. Pairing core GNSS technology with corrections delivered by data providers like TerraStar enables cm-level GNSS positioning in the wide variety of conditions seen in these applications. NovAtel CORRECT™ uses both PPP and RTK technologies to provide users with globally or locally available centimeter-level positioning. RTK has been widely used for many years. It enables the rapid acquisition of centimeter-level positions that are suitable for virtually all sky-visible high-precision applications. However, the logistical challenges associated with deploying and using RTK have meant that many applications have not been able to reap the benefits of high-precision positioning. NovAtel CORRECT™ with PPP expands the availability of centimeter-level positioning into many of these previously un-served applications. It combines globally valid and distributed corrections with advanced PPP algorithms, and lies near the apex of high-precision positioning technologies. This presentation will introduce, demonstrate, and analyze recent developments in NovAtel’s PPP technology. The primary focus of the developments has been on improving the initial convergence time. This is a critical attribute of PPP for real-world, real-time users. Two additions to the NovAtel’s PPP technology have enabled improvements in initial convergence: application of ionosphere corrections from a global ionosphere model; and support for additional GNSS constellations. Both additions have been made possible by corresponding additions to the real-time PPP correction feed provided by TerraStar. By acting to constrain the PPP solution initially, the ionosphere corrections resulting from the global ionosphere model improve initial convergence to the 40-50 cm horizontal level. This accuracy level can be achieved nearly immediately (1 minute or less) after obtaining the first PPP solution. The global ionosphere model is generated using observations from TerraStar’s global station network. The accuracy of the model depends on the location and ionosphere conditions: typical accuracies of the ionosphere slant delays provided by the model are between 20 and 50 cm, depending on the elevation angle of the satellite. Initial convergence is also improved through support for additional GNSS constellations: BeiDou, Galileo and QZSS. Multi-constellation PPP improves performance because of the increased number of observations and improved structure of the new GNSS signals. Currently, the use of multi-constellation corrections provides noticeable benefits in East-Asia and Oceania, while the benefit in other areas is minor. However, the situation is changing in coming years, because the European Union, People's Republic of China and Japan are launching more satellites. Real-time global ionosphere model and multi-GNSS results are shown in this presentation. PPP with the convergence improvements is tested in the variety of locations including Canada, Germany, Singapore and United Kingdom using static data. In addition, kinematic test results are shown. Significant convergence improvements are shown, particularly in terms of the convergence to the 50 cm horizontal error.