Component of SBAS

• SBAS


  Satellite Based Augmentation Systems
• SBAS


  • Provide services for improving the accuracy, integrity and availability of basic GNSS signals
• Accuracy


  Enhanced through the transmission of wide-area corrections for GNSS range errors
• Integrity


  Enhanced by the SBAS network quickly detecting satellite signal errors and sending alerts to receivers that they should not track the failed satellite
• Signal availability


  Can be improved if the SBAS transmits ranging signals from its satellites
• SBAS system components


  1. Reference stations

  2. Master station

  3. Uplink stations

  4. Geosynchronous satellites
• Reference stations


  Geographically distributed throughout the SBAS service area, receive GNSS signals and forward them to the master station
• Master station


  Can accurately calculate wide-area corrections since the locations of the reference stations are accurately known
• SBAS correction transmission


  1. Corrections are uplinked to the SBAS satellite

  2. Then broadcast to GNSS receivers throughout the SBAS coverage area
• User equipment


  Receives the corrections and applies them to range calculations
• WAAS


  Wide Area Augmentation System developed by the US Federal Aviation Administration to provide GPS corrections and a certified level of integrity to the aviation industry
• WAAS operation


  1. Wide Area Master Station receives GPS data from Wide Area Reference Stations

  2. Calculates differential corrections

  3. Uplinks these to two WAAS geostationary satellites for broadcast across the United States
• WAAS corrections


  Separate corrections are calculated for ionospheric delay, satellite timing, and satellite orbits
• WAAS broadcast


  Correction data is broadcast on the same frequency as GPS, allowing use of the same receiver and antenna equipment
• EGNOS


  European Geostationary Navigation Overlay Service, an augmentation system that improves the accuracy of positions derived from GPS signals and alerts users about the reliability of the GPS signals
• EGNOS coverage


  Three EGNOS satellites cover European Union member nations and several other countries in Europe
• MSAS


  MTSAT Satellite Based Augmentation Navigation System, an SBAS that provides augmentation services to Japan
• GAGAN


  GPS-Aided GEO Augmented Navigation System, an SBAS that supports flight navigation over Indian airspace
• SDCM


  System for Differential Corrections and Monitoring, developed by the Russian Federation to provide accuracy improvements and integrity monitoring for both the GLONASS and GPS navigation systems
• SNAS


  Satellite Navigation Augmentation System, planned by China to provide WAAS-like service for the China region
• GBAS


  Ground Based Augmentation System, provides differential corrections and satellite integrity monitoring to receivers using a VHF radio link
• GBAS applications


  Used for applications that require high levels of accuracy, availability and integrity, such as airports