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GNSS Development Status and Future Work Eric Chatre, EC/ESA Rapporteur Technical WG, GNSS Panel

GNSS Development Status and Future Work Eric Chatre, EC/ESA Rapporteur Technical WG, GNSS Panel. Agenda Item 6. Outline. GNSS Elements GNSS Performance Requirements Definition of parameters Relationship betweens parameters Integrity Principles GNSS Standards Future Work. IOR.

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GNSS Development Status and Future Work Eric Chatre, EC/ESA Rapporteur Technical WG, GNSS Panel

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  1. GNSS DevelopmentStatus and Future WorkEric Chatre, EC/ESA Rapporteur Technical WG, GNSS Panel Agenda Item 6

  2. Outline • GNSS Elements • GNSS Performance Requirements • Definition of parameters • Relationship betweens parameters • Integrity Principles • GNSS Standards • Future Work

  3. IOR GNSS Elements Core Constellations GLONASS GPS Augmentations ABAS GBAS SBAS

  4. Aircraft-Based Augmentation System (ABAS) • Stand-alone technique implemented in user equipment/software • No accuracy improvement, lateral guidance only • Provides integrity based on consistency check • Needs redundant satellite measurements (5 or more satellites in view with good geometry) • Integrity only • Performance and availability limited to some phases of flight

  5. Satellite-Based Augmentation System (SBAS) • Objectives • Improve accuracy of GPS or GLONASS by providing corrections for • Satellite errors : clock and ephemeris • Ionospheric errors : model over a geographic area • Provide integrity information • Lateral and vertical guidance • Improved availability,

  6. Satellite-Based Augmentation System (SBAS) (cont.) • Architecture • Network of stations covering a wide area (e.g. continent) • Transmission of information to users through geostationary satellites • Coverage and Service areas • Coverage : Wherever the geostationary signals are received • Service : Wherever operations have been approved by States

  7. GEO GPS Reference Stations Uplink Station SBAS Message Master Station SBAS Architecture

  8. Ground-Based Augmentation System (GBAS) • Objectives • Improve accuracy of GPS or GLONASS by providing for each satellite a composite correction • Satellite errors : clock, ephemeris correction valid locally • Ionospheric errors : local correction • Tropospheric errors : local correction • Provide integrity information

  9. Ground-Based Augmentation System (GBAS)(cont.) • Architecture • Ground Reference Station (typically 1 per airport) • Transmission of information to users through a VHF data link (108 to 118 MHz) • Coverage • Approach area (ILS like coverage) • Terminal area (positioning service)

  10. GPS and/or GLONASS, GEOs User VHF DATA LINK Reference station and VDB GBAS Architecture

  11. Aviation Performance Requirements for GNSS (signal-in-space)

  12. Interpretation of parameters • Accuracy : Characterize typical behavior of the system in presence of nominal error components • Integrity : Limit risk of abnormal behaviour of the system due to errors resulting from system failures • -Integrity Risk • -Alert Limit • -Time to Alert • Continuity : Limit risk of losing the service unexpectedly • Availability : Accuracy + Integrity [+ Continuity]

  13. Availabilty -Vertical accuracy/integrity is usually the main driver -Decreases as accuracy increases -Decreases as alert limit gets smaller GNSS performance is variable : in time in space New approach to ensure integrity for all users -Protection Level concept Availability Continuity Integrity Accuracy Relationship between parameters

  14. Integrity principles User Computed Protection Level Probability 1-1.10-7 Computed Position Alert Limit Protection Level<Alert LimitNo Alert Protection Level>Alert LimitAlert

  15. GNSS Standards, Procedures, Guidance Material • Standards and Recommended Practices (ICAO Annex 10, Vol I) • GNSS NOTAMS and Phraseology (ICAO Annex 15, PANS-ABC Doc 8400, PANS- ATM Doc 4444) • Procedure Design Criteria (PANS-OPS, Doc 8168) • Geodetic Reference Datum and Data Base Requirements (ICAO Annexes 4,11,14 &15, WGS-84 Manual Doc 9674) • Information and guidance on implementation (GNSS Manual) • Industry Standards (RTCA and EUROCAE MOPS/MASPS)

  16. Industry Standards • The main actors are : • RTCA in the US, Special Committee 159 • EUROCAE in Europe, Working Group 28 • The Documents • Minimum Operational Performance Specifications (MOPS) • Minimum Aviation System Performance Standards (MASPS) • Existing Standards • ABAS/Basic GNSS receiver : DO-208 / ED-72 / (J)TSO-C129A • SBAS receiver : DO-229 C / TSO-145A/146A • GBAS Cat I receiver : DO-253A • Multi-Mode Receiver including GBAS : ED-88A

  17. Future Work • Evolution of currently standardized GNSS elements • GPS modernization with additional civil signal on L5 frequency (1176.45 MHz) • GLONASS modernization (GLONASS K) with additional civil signal in the 1164-1215 MHz band • Extention of SBAS standards to accomodate new signals • Extention of GBAS standards to accomodate new signals and cover Category II/III and surface operations

  18. Future Work (cont.) • New GNSS elements • GALILEO system with 3 civil signals and a dedicated integrity service • Ground-Based Regional Augmentation System (GRAS)

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