U.S. Space-Based Positioning, Navigation, and Timing (PNT) Policy and Modernization

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U.S. Space-Based Positioning, Navigation, and
Timing (PNT) Policy and Modernization
China Executive Management Development Training
(EMDT) MITRE, McLean, VA 25 July 2006 Michael
Shaw Director U.S. National Space-based PNT
Coordination Office
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Overview

• What is Space Based PNT and GPS
• How GPS and Its Augmentations Work
• GPS Performance
• Next-Generation GPS
• U.S. Policy
• International Cooperation

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What is Space Based PNT and GPS?

• Space Based PNT is GPS plus its augmentations
• GPS is a space-based radio-navigation system
• Satellites broadcast precise and synchronized
  time signals and data to allow users to estimate
  their position, velocity, and time
• Augmentations improve GPS performance

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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

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Operational Control Segment Facilities
COLORADO SPRINGS
CAPE CANAVERAL
Master Control Station
KWAJALEIN
ASCENSION
DIEGO GARCIA
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U.S. Augmentations
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International Augmentations
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Commercial GPS Applications Span A Wide Range of
Economic Activities
Satellite Operations
Power Grid Management
Personal Navigation
Surveying Mapping
Trucking Shipping
Aviation
Communications Network Synchronization
Recreation
Railroads
Fishing Boating
Offshore Drilling
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Example Applications

• Cell phones (e.g. e 911
• services)
• Farming
• Boating
• Fishing
• Tracking wildlife
• Atmospheric/Space weather
• Visually impaired
• Computer security
• Games

• Navigation
• -- Aircraft, land vehicles,
• ships, satellites)
• Precise timing
• Surveying
• Map making
• Science
• Hiking
• Driving
• Flying

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New Commercial Applications Are Developed Every
Day

• Open pit mining
• Child safety
• Automatic snowplow guidance
• Spacecraft control
• Power grid management
• Wireless mobile applications

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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 NowEmpowering the Future
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Overview

• What is Space Based PNT and GPS
• How GPS and Its Augmentations Work
• GPS Performance
• Next-Generation GPS
• U.S. Policy
• International Cooperation

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GPS How does it work?

• GPS receiver uses signal from at least four
  satellites to triangulate its position in space
• Receiver knows several pieces of information
• Location of satellites
• Time satellite sent data
• Time it received data
• Velocity data travels to receiver
• Using this information, the receiver calculates
  its distance from the satellite and ultimately
  its position on the Earth

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How GPS Works
Time Orbit Position
Receiver
Calculates 3-Dimensional Location and Time
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Location Determination3D example
Intersection of two spheres is a circle
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Location Determination3D example
Intersection of three spheres is two points
The receiver dismisses the point located in
space, leaving only one possible position on the
earth
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So Why Do We Need 4 Satellites?

• If receiver had built in atomic clockneed 3

• With receivers inaccurate clockneed 4

• 4th satellite measurement allows receiver to
  solve for 4th unknown (correction factor)

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Overview

• What is Space Based PNT and GPS
• How GPS and Its Augmentations Work
• GPS Performance
• Next-Generation GPS
• U.S. Policy
• International Cooperation

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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 second civil signal
• Continuously assessing constellation health to
  determine launch need
• Next launch September 2006

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Recent Launches
Providing worldwide position, navigation timing
GPS IIR-1120 Mar 04 50th GPS Satellite
GPS IIR-12 23 Jun 04
GPS IIR-13 06 Nov 04
GPS IIR-14(M) 25 Sep 05 1st Modernized GPS
Satellite
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Civil GPS Performance Standard

• 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).

System accuracy far exceeds current standard
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Improving GPS Performance with Augmentations

• Augmentations enhance GPS accuracy, monitor
  integrity
• Sub-centimeter accuracy for geodesy, geology,
  etc.
• 2-5 cm accuracy for real-time positioning,
  surveying, etc.
• lt3 m vertical accuracy with 6 second time to
  alarm for aviation

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GPS Performance with WAAS

• U.S. Federal Aviation Administration developed
  the Wide Area Augmentation System (WAAS) to
  provide 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.

Augmented GPS fulfills rigorous user needs today
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Overview

• What is Space Based PNT and GPS
• How GPS and Its Augmentations Work
• GPS Performance
• GPS Modernization
• U.S. Policy
• International Cooperation

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Benefits of GPS Modernization

• For all users
• System-wide improvements in accuracy,
  availability, integrity, and reliability
• Backward compatibility
• 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
• Maintains international competitiveness

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GPS Modernization Program
Increasing System Capabilities w Increasing
Defense / Civil Benefit
Block IIA/IIR
Block III
Block IIR-M, IIF

• Backward compatibility
• 4th civil signal (L1C)
• Increased accuracy
• Increased anti-jam power
• Assured availability
• Navigation surety
• Controlled integrity
• Increased security
• System survivability

• IIR-M IIA/IIR capabilities plus
• 2nd civil signal (L2C)
• M-Code (L1M L2M)
• IIF IIR-M capability plus
• 3rd civil signal (L5)
• Anti-jam flex power

• Basic GPS
• Standard Service
• Single frequency (L1)
• Coarse acquisition (C/A) code navigation
• Precise Service
• Y-Code (L1Y L2Y)
• Y-Code navigation

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Second Civil Signal

• Designed to meet commercial needs
• Freely available since Dec 2005
• Currently on 1 satellite
• Will be on all future satellites
• Expected to generate over 5 billion in user
  productivity benefits

Benefits existing professional receivers
Increases accuracyfor consumers
Supports miniaturization, possible indoor use
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Third Civil Signal

• Designed to meet demanding requirements for
  transport safety
• May also enable global, centimeter-level accuracy
  using new techniques
• Opportunity for international interoperability

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Fourth Civil Signal

• Designed with international partners for
  interoperability
• Modernized civil signal at L1 frequency
• Original signal retained for backward
  compatibility
• More robust navigation across a broad range of
  user applications
• Improved performance in challenged tracking
  environments

Under trees
Inside cities
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GPS III

• Next-generation satellites are needed to
  accommodate increasing capabilities
• Civil benefits
• Provides operational capability for L2C and L5
• In combination with GPS IIR-M and IIF satellites
• Delivers L1C for interoperability with Galileo,
  QZSS
• Significant increase in system accuracy
• Improved availability of accuracy with integrity
• Revised acquisition strategy
• Spiral development approach to reduce risk,
  increase flexibility
• Separate contracts for space and ground segments
  to ensure best technology and most efficient
  implementation

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GPS III Proposed Accuracy

• Draft System Specifications
• Includes the effects of receivers
• Threshold low-cost/low-performance receiver
• Objective high-cost/high-performance receiver

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
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Overview

• What is Space Based PNT and GPS
• How GPS and Its Augmentations Work
• GPS Performance
• Next-Generation GPS
• U.S. Policy
• International Cooperation

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U.S. Policy History

• 1983 President Reagan offers free civilian
  access to GPS
• 1996 GPS declared a dual-use system under joint
  civil/military management
• 1997 Congress passes law requiring civil GPS to
  be provided free of direct user fees
• 2004 President Bush issues new U.S. policy on
  space-based PNT

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Policy Objectives

• Provide space-based civil PNT services free of
  direct user fees on a continuous, worldwide basis
• Open, free access to information needed to use
  civil GPS and its augmentations
• Improve performance of GPS and its augmentations
  - improving global services
• Ensure civil services exceed, or are at least
  equivalent to, those of other international civil
  space-based PNT services
• Improve resistance to interference for civil,
  commercial, homeland security, and scientific
  users
• Seek to ensure that international PNT systems are
  interoperable with GPS and its augmentations
• Or, at a minimum, are compatible

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Organizational Structure
WHITE HOUSE
Defense
Transportation
NATIONALSPACE-BASED PNT EXECUTIVE
COMMITTEE Co-Chairs Defense, Transportation
State
ADVISORYBOARD Sponsor NASA
Commerce
Homeland Security
NASA
COORDINATIONOFFICE Host Commerce
Joint Chiefs of Staff
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Overview

• What is Space Based PNT and GPS
• How GPS and Its Augmentations Work
• GPS Performance
• Next-Generation GPS
• U.S. Policy
• International Cooperation

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Global Navigation Satellite Services (GNSS)
Expanding

• Sep 2005 2nd civil GPS signal
• Dec 2005 first Galileo test satellite
• Dec 2005 3 GLONASS satellites
• This year European EGNOS operational
• Japan preparing for MSAS ops in 2007 and QZSS
• India moving forward with GAGAN and IRNS
• China Beidou, Compass

Interoperability key to seamless global operations
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U.S. Cooperation Strategy
Outlined in 2004 Presidential policy on
space-based positioning, navigation, and timing
(PNT)

• Provide civil GPS and augmentation services 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

• 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

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U.S. GPS Cooperation

• Ongoing cooperation with Europe, Japan, Russia
• Compatibility and interoperability
• National security
• Level playing field in global markets
• Seeking formal relations with Australia, India,
  Brazil
• Multilateral cooperation
• U.N. International Committee on GNSS
• ICAO, IMO, NATO

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Europe

• In 2004, United States and European Community
  signed historic agreement on GPS-Galileo
  cooperation
• Recognizes importance of compatibility/interoperab
  ility 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 establishedto 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)
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Japan

• Worlds largest consumer of GPS technology
• U.S.-Japan cooperation began in 1998
• Initially focused on interoperability with MSAS,
  Japans GEO-based augmentation system
• Promotes common principles such as free market
  access
• Annual plenary meetings, technical working groups
• 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 L1C, L2C, L5 signals
• GPS-QZSS interoperability achieved

MT-SAT used for MSAS
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Russia

• Cooperation started in 2004
• Working groups are pursuing GPS-GLONASS
  interoperability
• Enhanced PNT through combined service
• Combined search and rescue capabilities
• Currently pursuing formal cooperation agreement

GLONASS satellite
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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

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Summary

• U.S. policy encourages and promotes 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 in the future
• International cooperation is a priority
• Compatibility and interoperability are critical
• Opportunity for partnership with all nations

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Contact Information
Michael E. Shaw, Director National Space-Based
PNT Coordination Office Herbert C. Hoover
Building, Room 6822 1401 Constitution Avenue,
NW Washington, D.C. 20230 USA Ph (202)
482-5809 Fax [phone] Michael.Shaw_at_PNT.gov
Presentation and other GPS information
available www.pnt.gov