Global Navigation Satellite Systems Report of a Joint Workshop of the National Academy of Engineering and the Chinese Academy of Engineering (2012) / Chapter Skim
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U.S. GPS Policy, Programs, and International Cooperation Activities--David A. Turner
U.S. GPS Policy, Programs, and International Cooperation Activities--David A. Turner
Pages 25-34
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From page 25... ...
NATIONAL SPACE POLICY Figure 1 shows the organizational structure for developing GPS policy. The goal is to maintain leadership in the service, provision, and use of GNSS through the following actions: • Provide civil GPS services free of direct user charges available on a continuous, worldwide basis • Maintain constellation consistent with published performance standards and interface specifications • Use foreign PNT services to complement services from GPS • Encourage global compatibility and interoperability with GPS • Promote transparency in civil service provision • Enable market access to industry • Support international activities to detect and mitigate harmful interference 25
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From page 26... ...
policy promotes global use of GPS technology: • No direct user fees for civil GPS services • Provided on a continuous, worldwide basis • Open, public signal structures for all civil services • Promotes equal access for user equipment manufacturing, applications development, and value-added services • Encourages open, market-driven competition • Global compatibility and interoperability with GPS • Service improvements for civil, commercial, and scientific users worldwide • Protection of radio navigation spectrum from disruption and interference GPS PROGRAM STATUS GPS Constellation Status: • 31 operational satellites (baseline constellation of 24) -- 11 GPS IIA -- 12 GPS IIR -- 7 GPS IIR-M -- 1 GPS IIF • 3 additional satellites in residual status • IIF SV-2 scheduled to launch in July 2011
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-- IIR(M) capabilities plus -- Third civil signal L5 -- Reprogrammable Nav Processer -- Increased accuracy requirement -- 12-year design life • 2014–2024 -- GPS III: up to 32 satellites (Lockheed Martin)
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band -- 24 satellites ~2018 • Fourth civil signal (L1C) -- Designed with international partners for interoperability -- Modernized civil signal at L1 frequency -- More robust navigation across a broad range of user applications -- Improved performance in challenged tracking environments -- Original signal retained for backward compatibility -- Specification developed in cooperation with industry recently completed • Launches with GPS III in 2014 • On 24 satellites by ~2021
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Operations (2013–2028) -- Complete GPS L5 transition -- Will significantly improve availability and continuity during severe solar activity -- Provide additional protection against GPS interference -- Will continue to support single frequency users Nationwide Differential GPS System (Figure 3)
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modulation -- Real-time differential GPS corrections provided in Radio Technical Commission for Maritime Services (RTCM) SC-104 format -- No data encryption -- Real-time differential corrections for mobile and static applications -- Single coverage terrestrial over 92 percent of CONUS; double cover age over 65 percent of CONUS National Continuously Operating Reference Stations (CORS)
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From page 31... ...
government shall: encourage foreign develop ment of PNT services/systems based on GPS; seek to ensure foreign space-based PNT systems are interoperable with civil GPS and augmen tations; and, 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 gov ernments and other international organizations, and lead negotiations with foreign governments and international organizations regarding civil PNT matters.
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From page 32... ...
designed to be fully compat ible and highly interoperable with GPS -- Bilateral agreements to set up QZSS monitoring stations in Hawaii and Guam • U.S.-Russia Joint Statement issued December 2004 -- Working Groups on navigation signal compatibility and interoper ability, and search and rescue service • U.S.-China operator-to-operator coordination meetings held under ITU auspices in: -- Geneva, Switzerland - June 2007 -- Xian, China - May 2008 -- Geneva, Switzerland - October 2008 -- Hainan, China - December 2009 -- Coordination completed in Chengdu, China, in September 2010 -- The United States is interested in engaging in further bilateral discus sions with China on civil GNSS services and applications • U.S.-India Joint Statement on GNSS Cooperation 2007 -- Technical Meetings focused on GPS-India Regional Navigation Satel lite System (IRNSS) compatibility and interoperability held in 2008 and 2009 -- Continuation of ITU compatibility coordination is pending
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-- Other Member States of the United Nations -- International organizations/associations • Providers Forum -- Six space segment providers are members -- Purpose: o Focused discussions on compatibility and interoperability, encour aging development of complementary systems o Exchange detailed information on systems and service provision plans o Exchange views on ICG work plan and activities -- Providers have agreed that all GNSS signals and services must be compatible, and open signals and services should also be interoperable to the maximum extent possible -- Working definition of compatibility includes respect for spectral sepa ration between each system's authorized service signals and other systems' signals -- Interoperability definition addresses signal, geodetic reference frame realization, and system time steerage considerations APEC (Asia-Pacific Economic Cooperation) GNSS Implementation Team • GNSS Implementation Team (GIT)
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From page 34... ...
34 GLOBAL NAVIGATION SATELLITE SYSTEMS • Reports to Transportation Working Group through the Inter-modal Experts Group • Adopted a GNSS Strategy designed to promote adoption of GNSS technologies throughout the Asia Pacific region, especially with regard to transportation CONCLUSION • GPS performance is better than ever and will continue to improve -- Augmentations enable even higher performance -- New civil GPS signal available now -- Many additional upgrades scheduled • U.S. policy encourages worldwide use of civil GPS and augmentations • International cooperation is a priority • In pursuit of systems compatible and interoperable with GPS
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