About Augmentation/Regional Systems

Satellite-Based Augmentation Systems - Japan Civil Aviation Bureau

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Augmentation systems are designed to improve one or more qualities of a GNSS system or systems, such as accuracy, robustness, and signal availability.

Probably the most important of these are satellite-based augmentation systems (SBAS), but they also include ground-based systems, such as Australia’s Ground-Based Regional Augmentation System (GRAS), Russia’s proposed differential correction and monitoring service, and the U.S. Nationwide Differential Global Positioning System (NDGPS).

Satellite-based augmentation systems (SBASes) augment core satellite constellations by providing ranging, integrity and correction information, which increase accuracy, reliability, and availability of GNSS positioning. SBAS information is broadcast via transponders on geostationary satellites in the same band as the core constellations.

The elements of an SBAS system typically include a network of ground reference stations that monitor satellite signals; master stations processing reference stations data and generating SBAS signals, and uplink stations to that transmit the messages to the geostationary satellites.

Several commercial SBAS systems are providing services to users, including OmniSTAR (Fugro, The Netherlands), Starfire (NavCom Technology, United States), and Veripos (Subsea 7, United Kingdom).

Four non-commercial SBASes are currently under development:
Wide Area Augmentation System (WAAS), United States, commissioned for initial safety-of-life use in 2003.
European Geostationary Navigation Overlay Service (EGNOS), Europe; initial operations started in 2005.
GPS Aided GEO Augmented Navigation (GAGAN), India; scheduled for completion in 2008.
MTSAT (Multi-functional Transport Satellite) Satellite Based Augmentation System (MSAS), Japan; two MTSAT satellites launched in 2005-2006.

Regional systems provide additional signals from satellites operating over a given geographical area that are compatible with one or more GNSS systems. Regional satellite positioning systems proposed or under development include:
    The Indian Regional Navigation Satellite System (IRNSS) will include three satellites in geostationary orbit and four satellites in geosynchronous orbit, transmitting L-band and S-band signals and providing coverage primarily for the Indian land mass. The first satellite is planned for launch in mid-2009 and a complete constellation currently scheduled to be in place by 2011.
    The Quasi-Zenith Satellite System (Japan) proposes three inclined geosynchronous orbit (IGSO) satellites operating over Japan and surrounding areas and transmitting signals that are compatible and interoperable with existing and future modernized GPS signals. First launch is not expected until at least 2009.