What is SBAS?

The SBAS (Satellite-Based Augmentation System) provides free corrections to positioning receivers in the area by sending local ionospheric information via geostationary satellites. The accuracy which can be achieved with SBAS is around 1 m or better.

Historically SBAS originates as a civil aviation safety-critical system that supports wide-area or regional augmentation through the use of geostationary (GEO) satellites which broadcast the augmentation information, including ionosphere corrections and ephemeris long-term corrections next to range corrections (the "fast corrections" in the DO 229 terminology). While the main goal of SBAS is to provide integrity assurance, it also increases the accuracy with position errors at meter level.

There are multiple SBAS systems operating around the globe, including WAAS (US), EGNOS (Europe), GAGAN (INDIA) and MSAS (Japan). Other countries, such as Austrila, are also developing SBAS systems to provide service in their regions. The figure below shows the coverage of the SBAS systems around the globe, including the ones that are under development.