Satellite-Based Augmentation System (SBAS) Integrity Services Presented To: Munich, Germany Date: March 8, 2010 By: Leo Eldredge, Manager GNSS Group, FAA
FAA Satellite Navigation Program 2
Wide Area Augmentation System - 2003 38 Reference Stations 3 Master Stations 4 Ground Earth Stations 2 Geostationary Satellite Links 2 Operational Control Centers 3
WAAS LPV Coverage 4
SBAS Future Considerations Dual Frequency GNSS Services in protected aeronautical bands Enables direct estimation and removal of ionospheric delay errors Single largest source of vertical position uncertainty Most significant remaining threats are satellite failure based Design a new VPL equation targeting single satellite faults New SBAS being developed by India and Russia Investigate potential to expand LPV to global coverage 5
Current International Signal Plans L5 L2 L1 GPS (US) GLONASS (Russia) Future CDMA signal Galileo (Europe) COMPASS (China) IRNSS (India) QZSS (Japan) SBAS (US Europe India Japan) 1170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300 Frequency (MHz) 1560 1570 1580 1590 1600 1610 6 6
Current Reference Networks -Courtesy of Todd Walter, Stanford University 7
LPV-200 Coverage Estimated (Single Frequency GPS) WAAS EGNOS MSAS -Courtesy of Todd Walter, Stanford University 8
Future LPV-200 Coverage (Dual Frequency GPS) WAAS EGNOS MSAS -Courtesy of Todd Walter, Stanford University 9
WAAS, MSAS, EGNOS, GAGAN and SDCM Reference Networks -Courtesy of Todd Walter, Stanford University 10
WAAS, MSAS, EGNOS, GAGAN & SDCM (Dual Frequency GPS) -Courtesy of Todd Walter, Stanford University 11
Expanded Networks -Courtesy of Todd Walter, Stanford University 12
WAAS, MSAS, EGNOS, GAGAN & SDCM (Dual Frequency GPS + Expanded Networks) -Courtesy of Todd Walter, Stanford University 13
Objective: Worldwide Approach & Landing Approach capability with no airport equipment. Landing capability in all weather. Based on Open Service. Robust against: ionospheric storms constellation weakness RFI (scheduled, accidental or malevolent). changes in GNSS constellation performance Aviation does not want to be brittle! 14 14
Advanced Receiver Autonomous Integrity Monitoring (ARAIM) GPS Compass VPL VPL VPL VPL Galileo GLONASS 15
Advanced RAIM (ARAIM) + Integrity Support Message (ISM) Dual frequency open service Fast single faults & most multiple faults detected on the aircraft GNSS #1 Ground Control Nation-state approves ARAIM on dispatch or airspace entry GNSS #2 Ground Control ISM for GNSS #1 ISM for GNSS #2 16
Who provides or validates the Integrity Support Message? dual frequency open service fast single & most multiple faults GNSS #1 Ground Control Nation-state: approves ARAIM on dispatch Validate or generate ISM: GBAS or SBAS or GNSS GNSS #2 Ground Control ISM for GNSS #1 ISM for GNSS #2 17
Worldwide Coverage for LPV-200 & ARAIM Availability of 99.5% Weak Constellation: 21 GPS & 24 Galileo failure prone satellites weaker satellites URA =.5 m URE =.25 m Bias =.75 m URA = 1 m URE =.5 m Bias =.5 m 10-5 10-4 10-3 10-2 100% 99.8% 98.6% 57% 99.8% 99.6% 97.3% 48% URA = 2.4 m URE = 1.2 m Bias =.5 m 94.1% 76% 44.2% 0% 18
ARAIM Results for 30 SVs & URA =.5 m URA = 0.5m, Bias = 0.5m URA = 0.5m, Bias = 0.5m, URE = 0.25m, rbias = 0.1m 80 80 60 60 40 40 Latitude (deg) 20 0-20 Latitude (deg) 20 0-20 -40-40 -60-60 -80-80 -150-100 -50 0 50 100 150 Longitude (deg) -150-100 -50 0 50 100 150 Longitude (deg) < 15 < 20 < 25 < 30 < 35 < 40 < 45 < 50 > 50 99.5% VPL - 20.46 m avg., 35m avail = 99.99% < 50% > 50% > 75% > 85% > 90% > 95% > 99% >99.5% >99.9% For VAL = 35m, NDP & Acc: 97.77% coverage at 99.5% availabilit ARAIM currently predicated upon a user update rate of ~ 1hour 19
Are We Done? Functional Hazard Analysis Minor Slight increase in crew 10-3 workload Major Significant increase in 10-5 workload, Possible injury Lateral navigation, Non-precision approach (RAIM) Severe Major 10-7 Unmanageable increase in workload, Possible fatality Vertical guidance, LPV 200 (WAAS), Category I (LAAS) Catastrophic Multiple fatalities, 10-9 Loss of aircraft Zero visibility, Category II & III (LAAS) 20 20
Conclusions Single frequency coverage is good within the countries fielding SBAS Dual frequency extends LPV coverage outside reference networks Expanding networks into southern hemisphere could allow global coverage of land masses ARAIM Potential for Multi-Constellation GNSS 21
Questions 22