Development of Pseudo lite Based Augmentation System (PBAS)

Satellite Based Augmentation System (SBAS) is a civil aviation safety-critical system that supports vertical guidance through the use of Geostationary Earth Orbit (GEO) satellite (RTCA, 2006). Many countries already have implemented their own SBAS, and it is widely being used. Because of high-level navigation performance of SBAS, it is being used not only in aviation application but also in car navigation, smartphone application, etc. In order to take advantage of SBAS, Korea also started developing its own SBAS, and many results have been achieved in recent 4 years through the national R&D program (MLTM, 2014). This paper will introduce development of Pseudolite Based Augmentation System (PBAS) and real-time field test results which are the latest results of the project. PBAS is composed of several Wide-area Reference Stations (WRSs) which collect GNSS measurements and navigation data, Wide-area Master Station (WMS) which generates correction and integrity information using the data collected from WRSs, and pseudolite which takes the same role with GEO satellite in SBAS. All the algorithms in PBAS are designed to be suited for Korean local condition and performance of the algorithm has been verified with sufficient tests. Pseudo lite broadcasts GNSS augmentation message through the GPS L1 frequency signal, so that commercial SBAS enabled receivers can receive the messages without any modification. Real time field test was conducted with commercial low-cost GPS receiver and car navigation equipment. Test results show that PBAS improves positioning accuracy about 50%. The developed algorithms and pseudolite-based augmentation message broadcasting system are expected to be utilized in development of Korean SBAS.