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Satellite Based Augmentation Systems - SBAS

Satellite Based Augmentation Systems - SBAS. Lecturer: Michael O'Grady Course: MSc Ubiquitous & Multimedia Systems Unit: Context Sensitive Service Delivery Lecture: SBAS. Objectives. Outline current developments in Satellite Based Augmentation Systems (SBASs).

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Satellite Based Augmentation Systems - SBAS

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  1. Satellite Based Augmentation Systems - SBAS Lecturer: Michael O'Grady Course: MSc Ubiquitous & Multimedia Systems Unit: Context Sensitive Service Delivery Lecture: SBAS

  2. Objectives • Outline current developments in Satellite Based Augmentation Systems (SBASs)

  3. Satellite - Current Developments • Global Navigation Satellite System (GNSS) • Aims to resolve the conflict between civilian and military demands • seeks to provide position readings to within 3 metres • Two phases • GNSS-1 • Resolves most technical issues • Political issues still remains • Introduces Satellite Based Augmentation Systems (SBASs) • GNSS-2 • Seeks to provide a global infrastructure for positioning and timing

  4. GNSS-1 - EGNOS • European Geostationary Navigation Overlay System (EGNOS) • Developed by • European Commission • Eurocontrol • European Space Agency • Coverage area includes • all Europe, Africa and the Middle East • parts of Asia and South America • Uses INMARSAT-3 satellites for broadcasting correctional and integrity data • Scheduled for launch in 2006

  5. GNSS-1 - WAAS • Wide Area Augmentation System (WAAS) • Designed by the Federal Aviation Authority (FAA) • Designed to provide precise navigational services to aircraft for the duration of flight • Network of 25 ground stations spread across the USA • INMARSAT-3 used to broadcast connections • same frequency as GPS signal • Receiver must be WAAS enabled • Currently being deployed

  6. GNSS-1 - LAAS • Local Area Augmentation System (LAAS) • intended to operate when WAAS cannot • I.e when visibility is less than 1 km • Deployed in the immediate vicinity of airports • Will only broadcast data to aircraft in sight of the corresponding ground reference station

  7. GNSS-1 - MSAS • Multifunctional Transport Satellite Augmentation System (MSAS) • Services include • Navigation • Meteorology • Architecture • 24 ground stations • 2 satellites • Features • Area covered include most Asia/Pacific air space • Compatible with EGNOS and WAAS • Developed solely by Japan

  8. GNSS – Developments • India • GAGAN • China • SNAS • Canada • CWAAS

  9. EGNOS - Services • GEO Ranging • GPS-like signals • GMSS Integrity Channel • Signal integrity information • Wide Area Differential (WAD) • Differential corrections

  10. EGNOS - ARCHITECTURE • Four Segments • Space • Ground • User • Support Facilities

  11. EGNOS Diagram

  12. EGNOS – Space Segment • Three Geostationary transponders • INMARSAT-3 AOR-E • INMARSAT-3 AOR-W • ESA ARTEMIS

  13. EGNOS Ground Segment - RIMS • Ranging and Integrity Monitoring Stations (RIMS) • GPS, GLONASS, EGNOS(!) • 34 stations (mainly in Europe) • GPS/GLONASS/EGNOS receiver • Atomic clock • Network access • RIMS tasks • Pseudorange measurements • Demodulate SIS messages • Mitigate multipath & interference • Verify signal integrity • Packet & transmit data to MCC

  14. EGNOS Ground Segment - MCC • Mission/Master Control Centre (MCC) • 4 stations in Europe • Monitoring & control of EGNOS • Real-time software processing • MCC tasks • Integrity determination • Pseudo-range corrections for each satellite • Ionospheric delay • Generate Satellite (EGNOS) ephemeris

  15. EGNOS Ground Segment - NLES • Navigation Land Earth Station (NLES) • Two for each satellite (EGNOS) • 1 primary • 1 backup • One for Test & Validation • NLES Tasks • Generate GPS-like signal • Generate GIC signal (GNSS Integrity Channel) • Generate Wide Area Differential (WAD) signal • Transmit signals to GEO (EGNOS)

  16. EGNOS Ground Segment - EWAN • EGNOS Wide Area Network • Links all EGNOS ground-based components

  17. EGNOS – User Segment • EGNOS Receiver • Uses • Civil Aviation • Land • Marine

  18. EGNOS – Support Facilities • Support for • Development • Operations • Verifications

  19. SISNet • Signal In Space over the Internet (SISNet) • Provides EGNOS signal over standard TCP/IP connection • User Requirements • PDA/mobile phone • Wireless data connection e.g. GPRS • GPS card/receiver

  20. Why SISNet? • Recall … • Geostationary orbits • Low elevation angles So………… • Consider • In urban canyon? • At high latitudes?

  21. References • ESA WWW site • EGNOS • SISNet • SpringerLink • GPS Solutions

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