Space-Based PNT Modernization Update

David A. TurnerNational Space-Based PNT

Coordination OfficePresentation to the Munich Satellite Navigation SummitPresentation to the Munich Satellite Navigation Summit

February 21-23, 2006February 21-23, 2006

National Space-Based PNTCoordination Office

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OVERVIEW

• Background

• GPS Status & Modernization

• Augmentations Status

• Summary

Background

• GPS Status & Modernization

• Augmentations Status

• Summary

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GPS Background

• Active program for over 30 years– Created from separate programs in 1973– Developmental satellites began launch in 1978; operational satellites in

1989– Initial Operational Capability in 1993; Full Operational Capability in 1995

• Developed as a dual-use system– Military applications for US and Allied use – Civilian applications for worldwide use

• Consistent U.S. National Policy from both Executive and Legislative branches– Presidential Decision Directive - March 1996 captured by U.S. Public

Law - December 1997– U.S. Space-Based Positioning, Navigation, and Timing (PNT) Policy,

December 2004

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Dr. Getting Plaque

GPS Status & Modernization

• Background

• Augmentations Status

• Summary

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• 16 Block II/IIA satellites operational

• 12 Block IIR satellites operational– Modernizing up to 8 Block IIR satellites

• 1 Block IIR-M in orbit (launched Sep 25)– Set healthy on December 16, 2005

• 2nd IIR-M launch currently being scheduled– No earlier than May 25, 2006

• Continuously assessing constellation health to determine launch need

• Global GPS civil service performance commitment met continuously since Dec 93

29 Operating Satellites (to ensure 24)

GPS Constellation Status

Illustration reprinted courtesy of the GPS Joint Program Office

8Constellation PerformanceJanuary 1-December 31, 2004

PDOP (Geometry) AvailabilitySpecification - PDOP of 6 or Less, 98% of the timeActual - 99.98798%

Horizontal Service AvailabilitySpecification - 95% Threshold of 36 meters, 99% of the TimeActual – 2.74 meters

Vertical Service AvailabilitySpecification - 95% Threshold of 77 meters, 99% of the Time or BetterActual – 3.89 meters

User Range ErrorSpecification - 6 meters or Less, Constellation AverageActual – see next chart

Specification values from the Standard Positioning ServicePerformance Standard, October, 2001

System accuracy and availability far exceedcurrent specifications

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4.64.3

3.02.7

2.11.8

1.51.22

0

1

2

3

4

5

6

7

1990 1992 1994 1996 1997 1999 2001 2005

Year

RM

S U

RE

(m

)

GPS User Range Error (URE) History

Actual Performance

As of July 2005

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Why Modernize?

• For civil users, new signals provide:– More robustness against interference– Compensation for ionospheric delays– Wide-laning/tri-laning -- Resolves integer ambiguities caused

by cycle slips during precise carrier phase measurements

• For military users, new spectrally separated signals provide:– Protection of friendly use – Prevention of adversary exploitation– Preservation of civil use outside area of operations

• For both civil/military, system improvements in accuracy, availability, integrity, and reliability

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Block IIA/IIR Block IIIBlock IIR-M, IIFBlock IIIA:• Increased anti-jam power• Increased security• Increased accuracy• Navigation surety• Backward compatibility• Assured availability• Controlled integrity• System survivability• 4th civil signal (L1C)

IIR-M: IIA/IIR capabilities plus• 2nd civil signal (L2C)• M-Code (L1M & L2M)

• Eliminates SA for denial

• Anti-jam flex power

IIF: IIR-M capability plus• 3rd civil signal (L5)• Anti-jam flex power

Basic GPS• Std Service (16-24m SEP)

– Single frequency (L1)– Coarse acquisition (C/A)

code navigation• Precise Service (16m SEP)

– Y-Code (L1Y & L2Y)– Y-Code navigation

Increasing System Capabilities Increasing Defense / Civil Benefit

GPS Modernization The GPS Modernization Path 14

Source: GPS Joint Program Office

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Second Civil Signal (L2C)

• Improves service for ~ 50,000 current scientific/ commercial dual-frequency users

• Will enable higher civilian accuracy when combined with existing civil GPS signal (L1 C/A)

• Overcomes some limitations of L1 C/A– Higher effective power and improved data structure will reduce

interference and may enable better indoor use– Can be broadcast from an almost unlimited number of satellites

• Signal defined in IS-GPS-200D

L2C codeBegins with IIR-M sats24 Satellites: ~ 2012*

* Based on current schedule

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Third Civil Signal (L5)

• New signal structure for enhanced performance• Higher power than other GPS civil signals

– Higher power (no less than -154.9 dBW)

– Wider bandwidth (1176.45 MHz +/- 10 MHz)– Improves resistance to interference

• Frequency located in Aeronautical Radionavigation Services band (1164-1215MHz)

• Signal defined in IS-GPS-705

L5 code Begins with IIF sats24 Satellites: ~ 2015** Based on current schedule

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Ground Control Modernization

• New Master Control Station with:– Improved operator interfaces– IIR-M and IIF capabilities– Integrated Mission Operations Support Center– Launch and Early Orbit Anomaly Resolution and Disposal

Operations (LADO)

• Fully mission capable Alternate Master Control Station • Legacy Accuracy Improvement Initiative

– Additional information from National Geospatial-Intelligence Agency sites:

– Doubles amount of data being used for signal integrity and constellation performance monitoring

– Doubles amount of data used for satellite time and position estimation, resulting in more accurate satellite orbital position and clock data available to users

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Current GPS Monitoring Stations

USAF Sites – 6

Cape Canaveral

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Future GPS Monitoring Stations

Cape Canaveral

NGA Sites, AII – 6

NGA Sites, Non-AII -- 5

USAF Sites -- 6

Accuracy Improvement Initiative (AII)

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GPS III Goals

• Increased system accuracy

• Assured and improved level of unaugmented integrity– Compliments other sources (SBAS, RAIM)

• Improved availability of accuracy with integrity

• Backward compatibility with existing receivers

• Support for new signals in combination with IIR-M & IIF satellites– L2C, L5, M-code (existing with IIR-M, IIF)– L1C and future options for new navigation

messages, flexible power levels

• Smooth transition from GPS Block II to Block III

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• Government & Industry have completed studies of combined civil & military architectures

• Systems Requirements Reviews completed in summer 2005

• Separate space segment and control segment contracts will be awarded for the design phase of the program

• GPS III Capability Development Document (CDD) was reviewed by the Interagency Forum for Operational Requirements and approved by the Joint Requirements Oversight Council (JROC) in August 05

GPS III Status

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L1C Signal

• Modernized L1 civil signal

– In addition to C/A code to ensure backward compatibility

– Binary Offset Carrier [BOC] (1,1) modulation• Increased robustness and potentially accuracy for civil users

• Proposed as a common baseline L1 open service signal for GPS & Galileo

L1C Begins with GPS III satsFirst launch: ~ 2013*

For additional information contact: L1C_GPS@USGS.gov

* Based on current schedule

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GPS Modernization Schedule

Activity Implementation Date

SA set to zero May 2000

GPS IIR-M Enhancements - New L2 Civil (L2C) Signal - M-code on L1 & L2

1st satellite operational on

December 16, 2005

GPS IIF Enhancements - New L2 Civil (L2C) Signal - M-code on L1 & L2 - L5

1st launch currently scheduled

for January 2007

GPS III Enhancements - New L2 Civil (L2C) Signal - M-code with greater power - L5 - L1C

1st launch ~ 2013

OCS Enhancements On-going

Augmentations Status

• Background

• GPS Status & Modernization

• Summary

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Wide Area Augmentation System (WAAS)

• WAAS consists of:– 25 Reference Stations

• More being added in Canada/Mexico

– 2 Master Stations

– 2 Geosynchronous Satellites

– 3 Uplink Stations

• WAAS augments GPS to meet the integrity, availability, accuracy, and continuity for use in all phases of flight

• GPS/WAAS - primary navigation system in US national airspace– WAAS Commissioned in July 2003

– En-route through approach

• Allows reduction in ground-based navigation aids

• Interoperable with European EGNOS Japanese MSAS, and Indian GAGAN

Illustration reprinted courtesy of the U.S. Department of Transportation

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Nationwide Differential GPS System (NDGPS)

• Designed to an international, non-proprietary standard compliant with RTCM and ITU with frequencies optimum for surface transportation

• 50 countries operate compatible systems resulting in a seamless international navigation system

24Continuously Operating Reference Stations (CORS) Network

• A cooperative endeavor involving more than 130 government, academic, and private organizations

– Administered by the National Geodetic Survey of the National Oceanic and Atmospheric Administration

• Provides accurate, 3-dimensional, post-mission positioning ties to National Spatial Reference System

– Uses include land management, coastal monitoring, civil engineering, boundary determination, mapping, geographical information systems, and future improvements to weather prediction and climate monitoring

• CORS Network contained 850+ sites as of Oct 2004

– Growing at rate of 8 sites per month

– Includes all existing NDGPS/DGPS sites and FAA WAAS sites

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International GPS/GNSS Service

• Network of over 350+ stations throughout the globe

– Precision geodetic receivers produce GPS data on a continuous basis, ~ 35 also track GLONASS

• Over 200 contributing organizations throughout 80 countries to include the U.S. and India – A service of the International Association of Geodesy (IAG) since

January 1, 1994

• Advocates an open data policy, equal access

• Highest accuracy GPS & GLONASS satellite orbits anywhere

– 3-5 cm GPS , ~25-30cm GLONASS

– mm-level station positions and velocities

• IGS Central Bureau at NASA/Jet Propulsion Lab responsible for day-to-day management and coordination

– Global Data Center at NASA Goddard Space Flight Center

Summary

• Background

• GPS Status & Modernization

• Augmentations Status

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Summary

• GPS is rapidly evolving into a key part of the global infrastructure

• Civil service continues to exceed performance standards

• Next step in Modernization has begun

– IIR-M launch with L2C and M-code

– Enhancements will continue through GPS III

• Augmentations continue to be an integral component of U.S. Space-Based PNT Services

Continuously Improving GPS & Augmentation Services are benefiting users worldwide

National Space-Based PNT Coordination Office

Herbert C. Hoover Building, Rm. 682214th & Constitution Ave., NW

Washington, D.C. 20230

Phone: 001.202.482.5809Fax: 001.202.482.4429PNT.Office@pnt.gov

http://pnt.gov/