The Global Positioning System and Other Global Navigation
The Global Positioning System and Other Global Navigation Satellite Systems July 19, 2006 Jason Y. Kim, Senior Advisor National Space-Based Positioning, Navigation, and Timing (PNT) Coordination Office Washington, D. C. , USA
Overview Ø Introduction • GPS Performance • Next-Generation GPS • Cooperation with Galileo • Cooperation with GLONASS • Other Systems National Space-Based PNT Coordination Office, USA 2
The Global Positioning System • Baseline 24 satellite constellation in medium earth orbit • Global coverage, 24 hours a day, all weather conditions • Satellites broadcast precise time and orbit information on L-band radio frequencies • Two types of signals: – Standard (free of direct user fees) – Precise (U. S. and Allied military) • Three segments: – Space – Ground control – User equipment National Space-Based PNT Coordination Office, USA 3
U. S. Augmentations Nationwide Differential GPS Continuously Operating Reference Stations National Space-Based PNT Coordination Office, USA Wide Area Augmentation System Local Area Augmentation System 4
International Augmentations Differential GPS Networks Space-Based Augmentation Systems International GNSS Service Global Differential GPS System National Space-Based PNT Coordination Office, USA 5
GPS is a Global Public Service • Free access to civilian signals – One-way broadcast, like FM radio • Public domain documentation – Anyone can develop user equipment • Worldwide utility providing consistent, predictable, dependable performance – Critical component of global information infrastructure • Owned and operated by the U. S. Government – Paid for by U. S. taxpayers – Guided at a national level as multi-use asset – Acquired and operated by Air Force on behalf of USG Available Now—Empowering the Future National Space-Based PNT Coordination Office, USA 6
Organizational Structure WHITE HOUSE Defense Transportation State Commerce Homeland Security NATIONAL SPACE-BASED PNT EXECUTIVE COMMITTEE Co-Chairs: Defense, Transportation ADVISORY BOARD Sponsor: NASA Joint Chiefs of Staff COORDINATION OFFICE Host: Commerce National Space-Based PNT Coordination Office, USA 7
International Growth in Global Navigation Satellite Systems (GNSS) • • Europe: Galileo, EGNOS Russia: GLONASS Japan: MSAS, QZSS India: GAGAN, IRNS Australia: GRAS China: Beidou, Compass Canada: CWAAS Mexico: WAAS National Space-Based PNT Coordination Office, USA • Multilateral: International GNSS Service • Most major nations: Differential GPS, geodetic reference networks • Galileo partners: China, India, Canada, Mexico, Ukraine, Israel, Morocco, South Korea; discussions ongoing with Brazil, others 8
U. S. Cooperation Strategy Outlined in Presidential policy on space-based positioning, navigation, and timing (PNT) • Provide civil GPS and augmentations free of direct user fees on a continuous, worldwide basis • Provide open, free access to information needed to develop equipment • Improve performance of civil GPS and augmentations to meet or exceed that of international systems National Space-Based PNT Coordination Office, USA • Encourage international development of PNT systems based on GPS • Seek to ensure international systems are interoperable with civil GPS and augmentations – Or at a minimum, are compatible • Address mutual security concerns with international providers to prevent hostile use 9
Overview • Introduction Ø GPS Performance • Next-Generation GPS • Cooperation with Galileo • Cooperation with GLONASS • Other Systems National Space-Based PNT Coordination Office, USA 10
Constellation Status 29 Operational Satellites (Baseline Constellation: 24) • 16 Block II/IIA satellites • 12 Block IIR satellites – Modernizing 8 remaining Block IIR satellites • 1 Block IIR-M satellite – Transmitting new L 2 C signal • Continuously assessing constellation health to determine launch need – Next launch: September 2006 – All future satellites will feature L 2 C National Space-Based PNT Coordination Office, USA 11
Civil GPS Performance Standards U. S. commitments to civil GPS performance are documented in the GPS Standard Positioning Service Performance Standard (2001) “In support of the service availability standard, 24 operational satellites must be available on orbit with 0. 95 probability (averaged over any day). At least 21 satellites in the 24 nominal plane/slot positions must be set healthy and transmitting a navigation signal with 0. 98 probability (yearly averaged). ” National Space-Based PNT Coordination Office, USA 12
GPS Signal in Space Performance Standard Decr easin g rang e err or Signal in Space RMS URE: Root Mean Square User Range Error System accuracy far exceeds current standard National Space-Based PNT Coordination Office, USA 13
Ground Segment Expansion for Improved GPS Accuracy • Tripling the amount of GPS monitor data to improve accuracy and integrity of existing system • 10 -15% improvement in accuracy of GPS data broadcast Alaska Schriever AFB Vandenberg AFB England USNO Wash, DC Bahrain Cape Canaveral South Korea Hawaii Ecuador Kwajalein Diego Garcia Ascension Tahiti Argentina Australia South Africa New Zealand Master Control Station (MCS) Alternate MCS Ground Antennas Air Force Monitoring Stations NGA Monitoring Stations National Space-Based PNT Coordination Office, USA Future NGA Monitoring Stations 14
Improving GPS Performance with Augmentations enhance GPS accuracy, monitor integrity – Sub-centimeter accuracy for geodesy, geology, etc. – 2 -5 cm accuracy for real-time positioning, surveying, etc. – <3 m vertical accuracy with 6 second time to alarm for aviation National Space-Based PNT Coordination Office, USA 15
GPS Performance with WAAS U. S. Federal Aviation Administration developed the Wide Area Augmentation System (WAAS) to provide the necessary accuracy, integrity, and availability to support flight operations during all phases of flight Based on observations from January to March 2006. Results are valid when the Localizer Approach with Vertical Guidance (LPV) service is available. During this time frame, LPV was available 98% to 99% of the time. National Space-Based PNT Coordination Office, USA 16
GPS Performance with CORS Post-Mission Positioning Accuracy Based on dual-frequency GPS carrier-phase observations National Space-Based PNT Coordination Office, USA 17
Overview • Introduction • GPS Performance Ø Next-Generation GPS • Cooperation with Galileo • Cooperation with GLONASS • Other Systems National Space-Based PNT Coordination Office, USA 18
Benefits of Next-Generation GPS • For civil users: – – Higher standalone accuracy Robustness against interference Improved indoor, mobile, and urban use Interoperability with other GNSS constellations • For military: Enhances navigation warfare • For all users: – System-wide improvements in accuracy, availability, integrity, and reliability – Backward compatibility • Maintains international competitiveness National Space-Based PNT Coordination Office, USA 19
GPS Modernization Program Increasing System Capabilities w Increasing Defense / Civil Benefit Block IIA/IIR Basic GPS • Standard Service – Single frequency (L 1) – Coarse acquisition (C/A) code navigation • Precise Service – Y-Code (L 1 Y & L 2 Y) – Y-Code navigation Block IIR-M, IIF IIR-M: IIA/IIR capabilities plus • 2 nd civil signal (L 2 C) • M-Code (L 1 M & L 2 M) IIF: IIR-M capability plus • 3 rd civil signal (L 5) • Anti-jam flex power National Space-Based PNT Coordination Office, USA Block III • Backward compatibility • 4 th civil signal (L 1 C) • Increased accuracy • Increased anti-jam power • Assured availability • Navigation surety • Controlled integrity • Increased security • System survivability 20
Second Civil Signal (“L 2 C”) • Freely available since December 2005 – Currently on 1 satellite – Will be on all future satellites • Designed to meet commercial needs – Higher accuracy through ionospheric correction – Benefits thousands of existing high-end receivers using L 2 frequency – Higher effective power and improved data structure reduce interference, speed up signal acquisition, enable miniaturization of receivers, may enable indoor use 1227 MHz (L 2) Begins with GPS Block IIR-M First launch: 2005 24 satellites: ~2014 Signal defined in IS -GPS-200 • Expected to create over $5 billion in user productivity benefits • Full benefits will arrive after more satellites are launched and ground control system is upgraded National Space-Based PNT Coordination Office, USA 21
Third Civil Signal (“L 5”) • Designed to meet demanding requirements for transportation safety – Higher power than other GPS civil signals – Wider bandwidth improves resistance to interference – Uses highly protected Aeronautical Radio Navigation Service (ARNS) band – New signal structure for enhanced performance 1176 MHz (L 5) Begins with GPS Block IIF First launch: ~2007* 24 satellites: ~2016 Signal defined in IS-GPS-705 • May also enable global, centimeter-level accuracy via multi-signal techniques • Interoperable with Galileo’s E 5 a signal * Currently Reassessing Date National Space-Based PNT Coordination Office, USA 22
Fourth Civil Signal (“L 1 C”) • Designed with international partners to enable GNSS interoperability – Galileo Open Service – Japan’s Quasi-Zenith Satellite System – Possibility for GLONASS? 1575 MHz (L 1) • Modernized civil signal at L 1 frequency – Aeronautical Radio Navigation Service Band – Improved code and carrier tracking – New message structure Begins with GPS Block III First launch: ~2013 Signal defined in IS -GPS-800 (draft) • L 1 C/A will be retained for backwards compatibility National Space-Based PNT Coordination Office, USA 23
GPS III • Next-generation satellite bus needed to accommodate increasing power requirements • Revised acquisition strategy: – Spiral development approach to reduce risk, increase flexibility – Separate contracts for space and ground segments to ensure “best of breed” technology • Civil benefits: – Provides operational capability for L 2 C and L 5 • In combination with GPS IIR-M and IIF satellites – Delivers L 1 C for interoperability with Galileo, QZSS – Significant increase in system accuracy – Improved availability of accuracy with integrity National Space-Based PNT Coordination Office, USA 24
GPS III Proposed Accuracy • Draft System Specifications: ACCURACY (95%) THRESHOLD OBJECTIVE Horizontal 2. 5 m 0. 5 m Vertical 4. 5 m 1. 1 m Timing 5. 7 ns 1. 3 ns • Includes the effects of receivers – Threshold = low-cost/low-performance receiver – Objective = high-cost/high-performance receiver National Space-Based PNT Coordination Office, USA 25
Overview • Introduction • GPS Performance • Next-Generation GPS Ø Cooperation with Galileo • Cooperation with GLONASS • Other Systems National Space-Based PNT Coordination Office, USA 26
U. S. GPS Cooperation • U. S. Government has pursued formal cooperative arrangements with Europe, Japan, Russia since 1996 – To ensure compatibility (non-interference) and interoperability with foreign systems – To protect national security – To maintain level playing field in the global market • Additional efforts under way with Australia, India, Brazil • Multilateral cooperation established through U. N. International Committee on GNSS – As well as ICAO, IMO, NATO National Space-Based PNT Coordination Office, USA 27
GPS-Galileo Agreement • In 2004, United States and European Community signed historic agreement on GPS-Galileo cooperation, recognizing importance of compatibility and interoperability for all parties • Agreed to spectrally separate signals for military, civilian, and public regulated services • Agreed to implement a common, open, civil signal on both Galileo and GPS III, free of direct user fees • Working groups established to continue dialogue: – – Compatibility & Interoperability Trade & Commercial Applications Next-Generation GNSS Security Issues June 26, 2004, press conference at U. S. -EU Summit in Ireland (U. S. Sec. of State Colin Powell, Irish Foreign Minister Brian Cowen, EU Vice-President Loyola De Palacio) National Space-Based PNT Coordination Office, USA 28
Working Group A: Compatibility & Interoperability • Common civil signal for GPS and Galileo (L 1 C/L 1 F) – Centered on L 1 frequency used by GPS today – Agreement includes baseline modulation scheme but allows for “optimization” – Working Group A spent 21 months collaborating towards optimized signal design – Optimized design (“MBOC”) achieved in March 2006 – Satisfies all compatibility requirements – Still awaiting formal acceptance at political level • Time and geodesy – GPS and Galileo are based on different time standards and geodetic reference frames – Broadcasting GPS-Galileo Time Offset will solve time problem – Geodesy offset considered insignificant (<5 cm) National Space-Based PNT Coordination Office, USA 29
Improving GNSS Interoperability Characteristic Interoperability Benefit • Common time and reference • Navigation solutions can blend frames, or broadcast offsets measurements from different systems Most Important • Common carrier frequencies • Common antenna and receiver front end—lower power and cost; for Future common carrier tracking for higher Interoperability accuracy • Similar spreading • Common-mode dispersive errors modulation spectra removed in navigation solution for higher accuracy • Common spreading code • Lower cross-correlation sidelobes lengths and common code for better weak-signal reception; family common receiver processing for acquisition and tracking • Common data message • Common receiver processing for structure and encoding data message decoding and processing National Space-Based PNT Coordination Office, USA 30
Working Group B: Trade & Commercial Applications • Agreement includes provisions to maintain level playing field in GNSS market – Recognizes obligations under World Trade Organization – Affirms nondiscriminatory approach to trade in GNSS goods/services – Requires equal access to open signals and technical information needed for receiver development – Requires consultations on proposed measures affecting GNSS use • U. S. remains guarded about Galileo business plan – Not fully revealed due to concessionaire process – Licensing, royalties on chipsets not well understood – Fee structure for subscription services unknown • Interface Control Document for Galileo signals released in 2006 – Positive step towards providing access to technical information – However, questions remain • U. S. intends to convene Working Group B in fall time frame National Space-Based PNT Coordination Office, USA 31
Other Working Groups • Working Group C: Development of Next Generation Civil GNSS – Harmonization of GPS L 2 C, L 5, and L 1 C with Galileo E 5 safety-oflife and commercial services – Joint monitoring of GPS/Galileo civil signals – Joint coordination on system maintenance, satellite tracking, and back-up capabilities for civil applications – Next-generation augmentation techniques – Coordination of multilateral efforts to protect civil GNSS spectrum through non-ITU bodies (ICAO, IMO, etc. ) National Space-Based PNT Coordination Office, USA • Working Group D: Security Issues – Preventing technology transfer to third parties – Protection of Galileo Public Regulated Service 32
Overview • Introduction • GPS Performance • Next-Generation GPS • Cooperation with Galileo Ø Cooperation with GLONASS • Other Systems National Space-Based PNT Coordination Office, USA 33
Russia • United States and Russian Federation issued Joint Statement establishing cooperation in 2004 – Continue to provide GPS and GLONASS civil signals on a continuous, worldwide basis, free of direct user fees – Cooperate on matters of mutual interest related to GNSS in relevant international organizations and fora – Maintain radio frequency compatibility between systems – Promote civil interoperability between systems • Annual consultations and working groups established • Currently pursuing formal cooperation agreement GLONASS satellite National Space-Based PNT Coordination Office, USA 34
Working Group Meetings • Working Group 1: GPS-GLONASS Compatibility and Interoperability – October 2005, Moscow – June 2006, Cocoa Beach – Pursuing increased GPSGLONASS radio frequency compatibility and user equipment interoperability National Space-Based PNT Coordination Office, USA • Working Group 2: COSPAS/SARSAT (Search and Rescue Capability) – June 2005, London – March 2006, Moscow – September 2006, Las Vegas – Significant progress being made toward technical coordination of search and rescue capabilities on future satellites 35
Overview • Introduction • GPS Performance • Next-Generation GPS • Cooperation with Galileo • Cooperation with GLONASS Ø Other Systems National Space-Based PNT Coordination Office, USA 36
Japan • World’s largest consumer of GPS technology • U. S. -Japan cooperation began in 1998 – Initially focused on interoperability with MSAS, Japan’s GEO-based augmentation system – Promotes common principles such as free market access – Annual plenary meetings, technical working groups MT-SAT used for MSAS • Current focus is on Quasi-Zenith Satellite System (QZSS) – Regional system to complement, augment GPS over Japan – Will improve performance in urban canyons and mountains – Will freely broadcast GPS L 1 C, L 2 C, L 5 signals – GPS-QZSS interoperability achieved National Space-Based PNT Coordination Office, USA 37
Current View of GNSS Interoperability Characteristic Interoperability Benefit GLONASS-GPS • Common time and reference GLONASS-GALILEO frames, or broadcast offsets GLONASS-QZSS ? ? GPS-GALILEO QZSS-GALILEO ? GPS-QZSS • Navigation solutions can blend measurements from different systems • Common carrier frequencies • Common antenna and receiver front end—lower power and cost; common carrier tracking for higher accuracy • Similar spreading • Common-mode dispersive errors modulation spectra removed in navigation solution for higher accuracy • Common spreading code • Lower cross-correlation sidelobes lengths and common code for better weak-signal reception; family common receiver processing for acquisition and tracking • Common data message • Common receiver processing for structure and encoding data message decoding and processing National Space-Based PNT Coordination Office, USA 38
International Committee on GNSS • Multilateral group chartered through United Nations – First meeting: December 2005 • Purpose: Promote use of GNSS to improve efficiency and security of transport, search & rescue, geodesy, etc. , particularly in developing countries – Coordination among providers to improve compatibility and interoperability – Assistance to developing countries in integration of PNT services – Focal point for international information exchange – Forum for addressing future user needs National Space-Based PNT Coordination Office, USA 39
Summary • U. S. policy encourages worldwide use of civil GPS and augmentations • GPS performance is better than ever and will continue to improve – Augmentations enable high performance today – New GPS signal now available – Many additional upgrades scheduled • International cooperation is a priority – Compatibility and interoperability are critical National Space-Based PNT Coordination Office, USA 40
“Muito Obrigado!” PNT. GOV National Space-Based PNT Coordination Office 6822 Herbert C. Hoover Building Washington, D. C. 20230 USA pnt. office@pnt. gov +1 (202) 482 -5809 National Space-Based PNT Coordination Office, USA 41
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