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FAA GNSS Evolutionary Architecture Study

FAA GNSS Evolutionary Architecture Study. PNT Advisory Board Leo Eldredge, FAA GNSS Group March 27, 2008. FAA Satellite Navigation Vision. WAAS Architecture. 38 Reference Stations. 3 Master Stations. 4 Ground Earth Stations. 2 Geostationary Satellite Links. 2 Operational

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FAA GNSS Evolutionary Architecture Study

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  1. FAA GNSS Evolutionary Architecture Study PNT Advisory Board Leo Eldredge, FAA GNSS Group March 27, 2008

  2. FAA Satellite Navigation Vision

  3. WAAS Architecture 38 Reference Stations 3 Master Stations 4 Ground Earth Stations 2 Geostationary Satellite Links 2 Operational Control Centers

  4. WAAS LPV Coverage- Current 2008 -

  5. WAAS RNP Coverage- Current -

  6. 30 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 FY Development Operational Technical Refresh Operational JRC Technical Refresh Operational JRC Operational Launch 10/05 Lease Extension 9/06 Operational Launch 9/05 WAAS Enterprise Schedule FLP Segment (Phase II) LPV-200 Segment (Phase III) Dual Frequency (Phase IV) GEO #2 - Inmarsat GEO #3 – Intelsat GEO #4 – TeleSat GEO #5 – TBD GEO #6 – TBD Approach Development FOC Operational Launch 7/12 Operational Launch 7/15 ~6,000 WAAS Procedure Development

  7. Future Considerations • GNSS Modernization • GPS Dual Frequency (L1/L5) Service Provides Foundation • Potential for Larger GNSS or Use of Multiple GNSS Constellations • User Equipment Standards Development for New Signals • WAAS Dual Frequency Upgrade • Determine Appropriate Level of Dual Frequency Integration Required to Maximize Benefit With Minimum Impact • Established GNSS Evolutionary Architecture Study (GEAS) to Investigate Long Range Planning for Dual Frequency GPS • Develop Architectural Alternatives to Provide Worldwide LPV-200 Service in the ~2020-2030 Timeframe • Leverage Lessons Learned on WAAS/LAAS to Identify the Best Architecture Alternative to Meet Aviation Integrity Requirements • Participation With The GPS Wing, DoD National Security Space Office (NSSO), DOT Research & Innovative Technology Administration (RITA), and the Joint Planning & Development Office (JPDO) for NextGen

  8. GEAS Panel

  9. Determination of Integrity • Aircraft Based • Integrity is determined on board the aircraft using redundant ranging sources or sensors • e .g. RAIM, AIME, … • Ground Based • Integrity determined external to User • e.g. SBAS, GBAS, GRAS, GNSS Monitoring, … • Satellite Based • Determination of integrity is made on board the satellite using redundant components • e.g. Clock Monitoring (TKS), Signal Deformation Monitoring (SDM)

  10. Layered Approach • Ultimate integrity architecture will combine threat detection at all elements • Satellite • Best time to alarm (TTA) for rapid clock & digital errors • Ground • Necessary for absolute accuracy • Aircraft offers • Direct integrity monitoring by user • Mitigating ionosphere delays and local errors • Alternatives trade the degree of aircraft based augmentation (ABAS), constellation geometric robustness, user range accuracy, and augmentation • Need to find best trade for cost, TTA, integrity performance and constellation dependency

  11. GNSS integrity Channel (GIC) • Key Feature: • Integrity Determination External to the User • Key Enabler • Rapid Messaging Rate • TTA of 6.2 Sec • Key Benefit • Redundant Ranging Signals Not Required • Key Challenge • Meeting TTA

  12. Time-To-Alert (TTA) • A significant challenge with a worldwide system (i.e., Galileo or GPS-IIIC integrity) is meeting the 6.2 second TTA requirement • WAAS is just able to meet TTA with its North American network • A different approach is required for worldwide system • Allocate the TTA requirement to the aircraft or satellite fault detection

  13. Relative RAIM: Range Rate Residuals • Key Feature: • Real-Time Integrity Determination By User Using Carrier Phase Approach • Key Enabler • External Monitoring • Redundant Geometry • Key Benefit • TTA Latency Relaxed to Minutes Propagate the most recent monitored position with carrier phase only DHPL DVPL Most recent monitored position withcorresponding horizontal protection level (HPL) and vertical protection level (VPL) Growth in HPL and VPL due toRAIM on the carrier phase-baseddelta position updates From Prof. van Graas, Ohio University

  14. Absolute RAIM • Key Feature: • Real-Time Integrity Determination by the User (ABAS) • Key Enabler: • Redundant Ranging Sources • 30 or More SVs • Key Benefit • Latency Relaxed to Hours

  15. Preliminary Results Note: Predictions Valid for WAAS-Like Integrity Assured URA’s of 1 Meter or Less

  16. GEAS Next Steps • Phase 1 Report – Completed • Ready for Distribution • Future Work Plan • WAAS RRAIM Architecture • Detailed Analysis and Design Leading to Implementation of the RRAIM Architecture as the Dual Frequency Architecture for WAAS • Support to GPS-III/OCX Integrity & Continuity Assurance Activities • Provide Assistance to GPS Wing Program Office Team

  17. Questionshttp://gps.faa.gov

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