About the project
The SBAS-AFRICA programme is about deploying an end-to-end satellite-based augmentation system (SBAS) test-bed to demonstrate the potential benefits of implementing SBAS capabilities in Southern and Eastern Africa. The programme is funded by the United Kingdom Space Agency (UKSA) through its International Partnerships Space Programme (IPSP) initiative. The initial phase of the project, from February 2015 through March 2016, provides SBAS service coverage over South Africa in partnership with the South African National Space Agency (SANSA).
SBAS capabilities were pioneered by the United States of America (WAAS) and European Union (EGNOS) with the aim of delivering safety-of-life navigation services to the civil aviation sector. Similar systems have been developed by India (GAGAN) and Japan (MSAS). SBAS systems augment the positioning signals obtained from Global Navigation Signal Systems (GNSS) such as GPS, GLONASS and Galileo, providing integrity and enhanced accuracy to the signals via broadcast navigation data messages.
An SBAS system deploys a network of ground monitoring stations (GMS) at accurately-surveyed locations which track signals from GNSS satellites. A central SBAS data processing facility uses the GMS data to compute data messages comprising:
- combined orbit and clock error corrections for each GNSS satellite tracked
- a spatial grid of ionospheric error corrections for the coverage area
- integrity information
These data messages are uploaded via a Ground Uplink Station to geostationary (GEO) satellites equipped with specialised SBAS payloads and broadcast to end users employing suitably configured SBAS-enabled navigation receivers.