David A. Turner, Deputy Director Office of Space and Advanced Technology Bureau of Oceans, Environment and Science U.S. Department of State U.S. Space-Based

David A. Turner, Deputy Director

Office of Space and Advanced TechnologyBureau of Oceans, Environment and Science

U.S. Department of State

U.S. Space-Based PNTPolicy & International

Cooperation

April 7, 2008

2Moscow Satellite Navigation Forum 2008

Introduction

• Like the Internet, GPS has become a critical component of the global information infrastructure– Consistent policy and predictable, dependable

performance

– Augmentations improve service performance

• Presentation will address:– U.S. Space-Based Positioning, Navigation, and Timing

Policy

– Diplomatic efforts to ensure cooperation in providing Global Navigation Satellite Systems and Services


U.S. Policy History

• 1978: First GPS satellite launched

• 1978: Legislation requires federal radionavigation planning

• 1983: U.S. President offers free civilian access to GPS

• 1996: First U.S. GPS Policy. Established GPS as a dual-use system under joint civil/military management

• 1997: U.S. Congress passes law requiring the GPS standard positioning service to be provided free of direct user fees

• 2000: U.S. President set Selective Availability to “Zero”

• 2004: U.S. President issued U.S. Policy on Space-Based PNT

• 2007: U.S. President announces Selective Availability will no longer be built into modernized GPS III satellites


U.S. Policy Principles

• 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

• Encourage international development of PNT systems based on GPS

• Seek to ensure international systems are interoperable with civil GPS and augmentations

• Address mutual security concerns with international providers to prevent hostile use

Outlined in 2004 Presidential Policy on Space-Based Positioning, Navigation, and

Timing (PNT)


WHITE HOUSEWHITE HOUSE

ADVISORY BOARD

Sponsor: NASA

ADVISORY BOARD

Sponsor: NASA

NATIONALEXECUTIVE COMMITTEEFOR SPACE-BASED PNT

Executive Steering Group

Co-Chairs: Defense, Transportation

NATIONALEXECUTIVE COMMITTEEFOR SPACE-BASED PNT

Executive Steering Group


NATIONAL COORDINATION OFFICE

Host: Commerce

NATIONAL COORDINATION OFFICE

Host: Commerce

National Space-Based PNT Organization Structure

GPS International Working Group

Chair: State

GPS International Working Group

Chair: State

Engineering Forum


Engineering Forum


Ad HocWorking Groups

Ad HocWorking Groups

DefenseDefense

TransportationTransportation

StateState

InteriorInterior

AgricultureAgriculture

CommerceCommerce

Homeland SecurityHomeland Security

Joint Chiefs of StaffJoint Chiefs of Staff

NASANASA


2004 U.S. Space-Based PNT Policy(Excerpts focused on International Relations)

Goals: • U.S. space-based PNT systems and services remain essential

components of internationally accepted PNT services• Promote U.S. technological leadership in applications

involving space-based PNT services

To achieve this, the United States Government shall:• Encourage foreign development of PNT services/systems

based on GPS– Seek to ensure foreign space-based PNT systems are interoperable with

civil GPS and augmentations– At a minimum, ensure compatibility

The Secretary of State shall:• Promote the use of civil aspects of GPS and its augmentation

services and standards with foreign governments and other international organizations

• Lead negotiations with foreign governments and international organizations regarding civil PNT matters– And, as appropriate in coordination with the SECDEF, military PNT

matters


Planned GNSS

• Global Constellations– GPS (24+)

– GLONASS (24)

– Galileo (27)

– Compass (35)

• Regional Constellations– QZSS (3)

– IRNSS (7)

• Satellite-Based Augmentations– WAAS (3)

– MSAS (2)

– EGNOS (3)

– GAGAN (3)

– SDCM (2?)


U.S. Objectives in Working with Other GNSS Service Providers

• Ensure compatibility ― ability of U.S. and non-U.S. space based PNT services to be used separately or together without interfering with each individual service or signal– Radio frequency compatibility

– Spectral separation between M code and other signals

• Achieve interoperability – ability of civil U.S. and non-U.S. space-based PNT services to be used together to provide the user better capabilities than would be achieved by relying solely on one service or signal– Primary focus on the common L1C and L5 signalsPursue through Bi-lateral and

Multi-lateral Cooperation


The Goal of RNSS Civil Interoperability

• Ideal interoperability allows navigation with one signal each from four different systems with no additional receiver cost or complexity

GPS

QZSGALILEO

GLONASS

Interoperable = Better Together than Separate


U.S. - Europe Cooperation

• US-EU agreement signed in 2004 provides solid foundation for cooperation

• Action is now divided among four working groups set up by the agreement:– Technical, trade, and

security issues working groups have met

• Improved new civil signal (MBOC) adopted in July 2007

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)


U.S. - Russian Federation Cooperation

• U.S.- Russia Joint Statement issued in December 2004

• Several very productive technical working group meetings have been held:

– Russia WG-1 chair proposed adopting two new civil CDMA signals at L1, L5 to be interoperable with GPS

– Still under discussion within the Russian Government

• Negotiations for a U.S.-Russia Agreement on satellite navigation cooperation have been underway since late 2005


U.S. - Japan Cooperation

• Japan’s status as a world leader in GPS applications and user equipment makes it an important partner

• Regular policy consultations and technical meetings on GPS cooperation have been held since 1996 and led to the 1998 Clinton-Obuchi Joint Statement

• Both countries have benefited from the close relationship:– QZSS is designed to be compatible and

interoperable with GPS

– U.S. working with Japan to set up QZSS monitoring stations in Hawaii and Guam


U.S. - India Cooperation

• Policy and technical consultations on GPS cooperation underway since 2005– One aim is to ensure interoperability between GPS

augmentation system WAAS and India’s planned GAGAN augmentation system based on GPS

– Another important topic is ionospheric distortion and solutions

• U.S.-India Joint Statement on GNSS Cooperation issued in February 2007 in Washington– Bi-lateral meeting held in Bangalore in September 2007

– Technical Meeting focused on GPS-IRNSS compatibility and interoperability held in January 2008


U.S. - Australia Cooperation

• Long history of GPS cooperation between U.S. and Australia

• U.S.-Australia Joint Delegation Statement on Cooperation in the Civil Use of GPS signed April 19, 2007– Cooperation expands upon existing efforts to

ensure interoperability between GPS and Australia's Ground-based Regional Augmentation System (GRAS) and Ground Based Augmentation System (GBAS)

• U.S. Coast Guard NAVCEN posts a daily Position Dilution of Precision (PDOP) report in response to Australia’s concerns over planned GPS outages


International Committee on Global Navigation Satellite Systems (ICG)

• Emerged from 3rd UN Conference on the Exploration and Peaceful Uses of Outer Space July 1999– Promote the use of GNSS and its integration into

infrastructures, particularly in developing countries– Encourage compatibility and interoperability among

global and regional systems

• Members include:– GNSS providers (U.S., EU, Russia, China, India,

Japan)– Other Member States of the United Nations– International organizations/associations


2nd International Committee on Global Navigation Satellite Systems

(ICG)• ICG-2 held in September in Bangalore, India

• Established Providers Forum to address common issues

• Began implementation of the ICG Work Plan within established working groups:– A. Interoperability and compatibility

– B. Enhancement of performance of GNSS services

– C. Information dissemination, education, outreach & coordination

– D. Interaction with monitoring & reference station network organizations

• U.S. will host the 3rd ICG in December 2008


ICG Providers Forum

• Six space segment providers listed previously are members

• Purpose:– Focused discussions on compatibility and

interoperability, encouraging development of complimentary systems

– Exchange of detailed information on systems and service provision plans

– Exchange views on ICG work plan and activities

• Consensus reached at the first meeting on general definitions for compatibility and interoperability– Including spectral separation between each system’s

authorized service signals and other systems’ signalshttp://www.unoosa.org/oosa/en/SAP/gnss/icg.html

Moscow Satellite Navigation Forum 2008

Summary

• International cooperation in the context of National Space-Based PNT Policy principles is a top priority for the U.S. Government

• U.S. is actively engaged in bi-lateral and multi-lateral cooperation on space-based navigation issues

• As new space-based GNSS are emerging globally, interoperability is the key to “success for all”

Moscow Satellite Navigation Forum 2008

Contact Information

David A. TurnerDeputy Director

Space and Advanced TechnologyU.S. Department of State

OES/SAT, SA-23, Suite 410Washington, D.C. 20520

202.663.2397 (office)202.320.1972 (mobile)[email protected]

http://www.state.gov/g/oes/sat/http://pnt.gov/international/

BACK-UP


ICG Providers Forum Definition of Compatibility

Compatibility refers to the ability of space-based positioning, navigation, and timing services to be used separately or together without interfering with each individual service or signal.

• Radiofrequency compatibility should involve thorough consideration of detailed technical factors, including effects on receiver noise floor and cross-correlation between interfering and desired signals. The International Telecommunications Union (ITU) provides the framework for discussions on radiofrequency compatibility.

• Compatibility should also involve spectral separation between each system’s authorized service signals and other systems’ signals.

• Any additional solutions to improve compatibility are encouraged


Radio Frequency Compatibility

• Ensures that signals do not unacceptably interfere with use of other signals

• Requires thorough consideration of detailed technical factors, including

– Effects on receiver noise floor

– Crosscorrelation between interfering and desired signals

• International Telecommunication Union (ITU) provides framework

• Details are best worked bilaterally between providers


ICG Providers Forum Definition of Interoperability

Interoperability refers to the ability of open global and regional satellite navigation and timing services to be used together to provide better capabilities at the user level than would be achieved by relying solely on one service or signal.

• Ideal interoperability allows navigation with signals from at least four different systems with no additional receiver cost or complexity.

• Common center frequencies are essential to interoperability, and commonality of other signal characteristics is desirable.

• Multiple constellations broadcasting interoperable open signals will result in improved observed geometry, increasing end user accuracy everywhere and improving service availability in environments where satellite visibility is often obscured.

• Geodetic reference frames and system time standards should also be considered.

• Any additional solutions to improve interoperability are encouraged.


Main Benefit of Interoperability

• More Satellites Better Geometry Improves:– Satellite coverage navigate where could not before– Dilution of Precision accuracy is better everywhere

• Eliminates DOP holes (with open sky)– RAIM* integrity checked everywhere, all the time

• Eliminates RAIM holes (with open sky)– Phase ambiguity resolution for survey and machine

control applications

Geometry

* Receiver Autonomous Integrity Monitoring


Important for Interoperability

• Common Center Frequency– Like L5 & E5a

• Same Antenna Polarization• Common Signal Spectrum

– Identical receiver time delay with common spectrum

• Same coherent integration period for acquisition– Usually related to symbol rate– Different symbol rates may require separate

search correlators for acquiring signals

Essential (cost driver)

Desirable (ASIC gate count)

Important (no time bias or filter issues)


Other Interoperability Factors – System Time

• System time offset may affect interoperability, depending on the circumstance

• This is why system time offset parameters will be part of future GPS, Galileo, and QZSS messages– Permits use of only one or two extra satellites

• Conversely, GPS and GLONASS receivers function well without a time offset message– Receivers compute and remember time offset, to

high precision, if 2+3 or more satellites are in view• Time offset is a slowly changing solution variable

• No impact with common differential corrections – From the same reference station or network


Other Interoperability Factors – Geodesy

• Geodesy differences may affect interoperability, depending on the extent of the differences

• Much progress in eliminating geodesy offsets

– Continuing work is underway

• Current GNSS geodesy models are so nearly equivalent that most users are not affected

– Coordinate system differences are known and can be applied in the receiver software

– Also, no impact with common differential corrections


L51176.45 MHz

E5a1176.45 MHz

E5b1207.14 MHz

L21227.6 MHz

E61278.75 MHz

L11575.42 MHz

L11575.42 MHz

1242.9375-1248.625 MHz

1598.0625-1605.375 MHz

GLONASSGLONASS

GALILEOGALILEO

L51176.45 MHz

L21227.6 MHz

LEX1278.75 MHz

L11575.42 MHz

QZSSQZSS

GPSGPS MMMMMMMMMMMM P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)C/AC/AC/AC/A

MMMMMMMMMMMM P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)P(Y)C/AC/AC/AC/A

GNSS Frequency Bands and Signals

Possible futuresignal

L51176.45 MHz

L21227.6 MHz

E61278.75 MHz

L11575.42 MHz

Beidou/CompassBeidou/Compass

ITU Filings Here ITU Filings Here ITU Filings Here ITU Filings Here

Possible futuresignal

SBASSBAS

IRNSSBeidou/Compass & IRNSS

In S-band

Documents

David A. Turner, Deputy Director Office of Space and Advanced Technology Bureau of Oceans, Environment and Science U.S. Department of State U.S. Space-Based