SBAS

SBAS stands for Satellite-Based Augmentation System. It is a system designed to improve the performance of satellite navigation by providing corrections and integrity information via geostationary satellites, enhancing accuracy, reliability, and availability for GNSS users. SBAS can support multiple global navigation satellite systems, including GPS, GLONASS, Galileo, and BeiDou.

How SBAS works: A network of ground reference stations monitors the signals from GNSS satellites. A central processing facility computes corrections for satellite clock and orbit errors, ionospheric delays, and other biases, along with integrity information that indicates the reliability of the corrections. This information is sent to geostationary satellites, which broadcast it to users in a wide region. Receivers decode the SBAS message and apply the corrections to GNSS measurements, producing more accurate position fixes with enhanced confidence.

Services and coverage: SBAS provides integrity, availability, and improved accuracy, supporting general navigation and, in aviation, safety-critical operations. Some SBAS services are designed to meet aviation safety requirements and enable precision approaches. Examples of regional SBAS implementations include WAAS in North America, EGNOS in Europe, MSAS in Japan, and GAGAN in India. While these systems are regionally focused, their signals can be received over large areas, and they can be used in combination with other GNSS data to improve performance globally.

Applications and standards: SBAS is widely used to support aviation navigation, surveying, and other GNSS-enabled activities. It is developed and operated to meet international standards and regulatory requirements, with ongoing modernization to incorporate newer GNSS signals and improve resilience.

Limitations and future: SBAS performance depends on geographic coverage, ground infrastructure, and ionospheric conditions. It is complementary to GNSS and does not provide global coverage by a single system. Ongoing enhancements aim to expand regional coverage and interoperability across different SBAS networks.