标题: GNSS and GBAS Introduction_Honeywell [打印本页] 作者: 航空 时间: 2010-8-6 12:52:55 标题: GNSS and GBAS Introduction_Honeywell
GNSS and GBAS Introduction_Honeywell
作者: 航空 时间: 2010-8-6 12:53:15
Dave Jensen, John Howard Honeywell, Precision Landing Systems 29-30 Oct 2009 CAAC New Technology Seminar - GNSS GNSS and GBAS Introduction Honeywell.com GNSS and GBAS • Global Navigation Satellite System (GNSS) – Current implementations, applications – How it works – Accuracy, Integrity • Types of GNSS Augmentation • Ground Based Augmentation System (GBAS) – How it works – Architecture – Subsystems • GPS Accuracy and Aircraft Protection Levels – Un-augmented – With WAAS – With GBAS Dave Jensen/John Howard 2 CAAC New Technology Seminar – GBAS 29-30 October 2009 Honeywell.com Current GNSS GNSS Compass GPS Galileo GLONASS Origin China USA Europe Russia Operational 2015 1995 2012 1995 # Satellites NA / 35 30 / 32 NA / 30 19 / 24 21 150 k 22 200 k 23 222 k 19 100 k • Global Navigation Orbits 21,150 km 12.6h 22,200 km 12.0h 23,222 km 14.1h 19,100 km 11.3h Satellite Systems (GNSS) – Have become a global utility – Provide civilian and military (precise) positioning services – Consistent, predictable, dependable performance • Applications for GNSS Keep Growing – Agriculture, Aviation, Marine, Surveying, Traffic, Timing, Tectonics... P i i i ti ith h l ) Dave Jensen/John Howard 3 CAAC New Technology Seminar – GBAS 29-30 October 2009 – Precision navigation ( with help) Honeywell.com GNSS Theory of Operation Dave Jensen/John Howard 4 CAAC New Technology Seminar – GBAS 29-30 October 2009 Honeywell.com GNSS Theory of Operation • Each satellite transmits its position and a time signal • The signals are delayed by the distance traveled to user • From the delay, user calculates distance or “pseudorange” to each satellite • User determines where there pseudoranges “overlap” – This is your position! • GNSS Provides Position, but No Integrity and Limited Accuracy – Precision application require accuracy – Safety applications require integrity • Receiver Autonomous Integrity Monitor (RAIM) – Provides user with integrity of their position solution • Used in aircraft receivers – Requires at least 5 satellites in view – Receiver excludes 1 or 2 satellites • Determine a “position” (with satellite excluded) – Repeat for all satellites in view – Determine error bound (integrity) of position by • Discarding outlier “position” solutions Dave Jensen/John Howard 5 CAAC New Technology Seminar – GBAS 29-30 October 2009 • Computing variance of “position” solutions Honeywell.com GNSS Accuracy • GPS Position Errors can be up to 10 m • Predominant GNSS Error Sources are: – Ionosphere (up to 5 m) – Satellite Position (up to 2.5 m) – Troposphere (up to 2 m) – Satellite Clock (up to 2 m) – Multipath/Reflections (up to 1 m) – Calculation/Rounding (up to 1 m) • Poor Geometry of Satellites Increases these Errors – Geometric Dilution of Precision (GDOP) • Errors are Measurable, Locally-Correlated, but not Predictable • Need a System that can Reliably Measure the Errors and Make Available to Users – GNSS Augmentation! Dave Jensen/John Howard 6 CAAC New Technology Seminar – GBAS 29-30 October 2009 g Honeywell.com GNSS Augmentation Types • Enhance GNSS Accuracy and Integrity • Space Based Augmentation System (SBAS) – Network of ground stations takes local measurements – Control stations determine errors and transmits error “map” to satellites – Satellite transmits corrections “map”, integrity data to users e.g. “WAAS” augments GPS for North America •Ground Based Augmentation System* (GBAS) – Ground station determines local errors – Ground station broadcasts local corrections, integrity data directly to users e.g. “LAAS” augments GPS for an airport • Aircraft Based Augmentation System (ABAS) – Aircraft autonomously determines local errors – On-board GPS monitors provide integrity – RAIM concept with additional sensors and monitoring Dave Jensen/John Howard 7 CAAC New Technology Seminar – GBAS 29-30 October 2009 p g *Only GBAS provides required integrity, accuracy & availability for precision landing. Honeywell.com Current GNSS Augmentation1 GNSS Compass GPS (SPS) Galileo GLONASS WAAS (USA) CDGPS2 (C d ) SBAS NA Canada) EGNOS (Europe) MSAS3 ( Japan) EGNOS EGNOS p ) QZSS3 (Japan) GAGAN (India) GBAS NA SmartPathTM NA NA 1. As of October 2009. 2. CDGPS is not intended for aeronautical navigation applications. 3. MSAS provides GPS corrections and integrity. While QZSS provides additional high elevation satellites to improve vertical accuracy. Dave Jensen/John Howard 8 CAAC New Technology Seminar – GBAS 29-30 October 2009 Honeywell.com Ground Based Augmentation System Dave Jensen/John Howard 9 CAAC New Technology Seminar – GBAS 29-30 October 2009 Honeywell.com GBAS Concept • Take Multiple GNSS Pseudorange Measurements – For all satellites currently in view • Determine Correction (Average Error) of each PR Measurement – Filtered, then average of PR measurements • Monitor and Detect Known Threats to GNSS Integrity – Ensure integrity of PR measurements & corrections – Alert if integrity cannot be met • VHF Broadcast Corrections & Error Bounds (Type 1) – For validated satellites only – Variance (error bound) of broadcast correction • VHF Broadcast Ground & Tropospheric Data (Type 2) – Defines region in which corrections may be safely used –Provides parameters for tropospheric adjustment • VHF Broadcast Approach Paths (Type 4) – All Final Approach Segment (FAS) data Dave Jensen/John Howard 10 CAAC New Technology Seminar – GBAS 29-30 October 2009 – No aircraft database required Honeywell.com GBAS Architecture Satellite/GNSS Ground Aircraft Dave Jensen/John Howard 11 CAAC New Technology Seminar – GBAS 29-30 October 2009 Honeywell.com GBAS Architecture • GBAS is Comprised of 3 Subsystems – Satellite/GNSS – Aircraft – Ground • Satellite/GNSS Subsystem – Provides satellite status, position and timing signal – Has sufficient number of satellites to determine user position • Aircraft Subsystem – Applies broadcast pseudorange corrections (PRC’s) • Computes troposphere adjustment – Computes position using corrected PR’s only – Computes deviations from broadcast approach path – Determines if GLS approach is possible (safe) – Follows desired approach path to decision height (200 ft) • Runway visible – continue with GLS approach • Runway not – Dave Jensen/John Howard 12 CAAC New Technology Seminar – GBAS 29-30 October 2009 visible execute missed approach Honeywell.com GBAS Ground Subsystem • Ground Subsystem Provides – Pseudorange corrections for each satellite in view • With error bound – System (aircraft) integrity • Protects aircraft against satellite and/or signal errors • Protects aircraft against anomalous ionospheric errors • Protects aircraft against ground subsystem errors – Approach paths • Final Approach Segment (FAS) for all runway ends • No aircraft approach database required – Local tropospheric parameters • Necessary to compute aircraft tropospheric adjustment – Predicted availability • Availability for precision approaches in next 30 minutes • Estimates aircraft protection levels against alert limits Dave Jensen/John Howard 13 CAAC New Technology Seminar – GBAS 29-30 October 2009 Single GBAS provides all approaches for an entire airport. Honeywell.com Augmented GPS Performance1 System Direction Accuracy (95%) Protection Levels (95%) GPS2 (Global) Horizontal Vertical 2.55 m 4.55 m 50 – 100 m 100 – 200 m WAAS3 H i t l 0 70 11 16 (CONUS) Horizontal Vertical 0.70 m 1.20 m – m 19 – 31 m GBAS Horizontal < 0 50 1 – 3 (Airport) Vertical 0.50 m < 0.50 m m 3 – 5 m 1. Contribution to user position error. 2. April 2009 GPS SPS Performance Report. 3. July 2009 WAAS Performance Report. Dave Jensen/John Howard 14 CAAC New Technology Seminar – GBAS 29-30 October 2009 GPS satellites are ~25,000 km from user! Honeywell.com Recap • Global Navigation Satellite Systems (GNSS) Provide Position, but not Integrity – Up to 10 m position error – Aircraft use RAIM to determine integrity • GNSS Augmentation Improves Accuracy & Provides Integrity – Continent (SBAS), Airport (GBAS), Aircraft (ABAS) • GBAS provides Accuracy, Integrity & Approach Paths – Only GBAS provides accuracy, integrity, availability for precision landing • GBAS can Achieve 0.50 m Accuracy (95%) – Aircraft Protection Levels 1 to 5 m • Questions? Dave Jensen/John Howard 15 CAAC New Technology Seminar – GBAS 29-30 October 2009作者: drjones 时间: 2010-9-1 09:23:26 标题: 支持
