The availability and performance of global navigation satellite systems (GNSS) signals at high altitude is documented as the GNSS Space Service Volume (SSV). While different definitions of the SSV exist and may continue to exist for the different service providers, within the context of this booklet it is defined as the region of space between 3,000 km and 36,000 km above the Earth's surface, which is the geostationary altitude. For space users located at low altitudes (below 3,000 km), the GNSS signal reception is similar to that for terrestrial users and can be conservatively derived from the results presented for the lower SSV in this booklet.

A comprehensive assessment of the challenges and opportunities created by worldwide access to this revolutionary technology.

The Global Positioning System (GPS) is a satellite-based navigation system that was originally designed for the U.S. military. However, the number of civilian GPS users now exceeds the military users, and many commercial markets have emerged. This book identifies technical improvements that would enhance military, civilian, and commercial use of the GPS. Several technical improvements are recommended that could be made to enhance the overall system performance.

T. Ito, International Space University, Strasbourg Central Campus, 1 Rue Jean Dominique Cassini, Parc d'Innovation, 67400 lllkirch-Graffenstaden, France e-mail: ito@isu. isunet. edu M. J. Rycroft, CAESAR Consultancy, 35 Millington Road, Cambridge CB3 9HW, UK e-mail: Michael. J. Rycroft®ukgateway. net As Symposium Committee Chair for the 2003 International Space University (ISU) Symposium, and Editor of this Proceedings volume, respectively, we write this introduction. The success of previous ISU symposia suggests that the ISU has developed a unique and winning formula for a novel type of symposium. The characteristics of ISU symposia are that they: • Adopt a broad, and interdisciplinary, perspective • Address all aspects of the subject, ranging from policy, business, organisational, and legal issues to technical and scientific topics • Foster a constructive dialogue among very different sectors of the space community, and • Allow ample time for interactive discussions. The present Symposium is no exception. It considers the very timely topic of space-based systems for global positioning and navigation, ranging from the GPS system developed by the US military to the Russian GLONASS system, and on to the future European Galileo system. Other nations are planning regional augmentation systems.

The International GPS (Global Positioning System) Service for Geodynamics (IGS) began formal operation on January 1, 1994. This first annual report is divided into sections, which mirror different aspects of the service. Section (1) contains general information, including the history of the IGS, its organization, and the global network of GPS tracking sites; (2) contains information on the Central Bureau Information System; (3) describes the International Earth Rotation Service (IERS); (4) details collecting and distributing IGS data in Data Center reports; (6) describes how the IGS Analysis Centers generate their products; (7) contains miscellaneous contributions from other organizations that share common interests with the IGS. Zumberge, J. F. (Editor) and Liu, R. (Editor) and Neilan, R. E. (Editor) Jet Propulsion Laboratory NASA/CR-97-112582, JPL-Publ-95-18, NAS 1.26:112582 NAS7-1260; RTOP 465-23-03-21...

This Handbook presents a complete and rigorous overview of the fundamentals, methods and applications of the multidisciplinary field of Global Navigation Satellite Systems (GNSS), providing an exhaustive, one-stop reference work and a state-of-the-art description of GNSS as a key technology for science and society at large. All global and regional satellite navigation systems, both those currently in operation and those under development (GPS, GLONASS, Galileo, BeiDou, QZSS, IRNSS/NAVIC, SBAS), are examined in detail. The functional principles of receivers and antennas, as well as the advanced algorithms and models for GNSS parameter estimation, are rigorously discussed. The book covers the broad and diverse range of land, marine, air and space applications, from everyday GNSS to high-precision scientific applications and provides detailed descriptions of the most widely used GNSS format standards, covering receiver formats as well as IGS product and meta-data formats. The full coverage of the field of GNSS is presented in seven parts, from its fundamentals, through the treatment of global and regional navigation satellite systems, of receivers and antennas, and of algorithms and models, up to the broad and diverse range of applications in the areas of positioning and navigation, surveying, geodesy and geodynamics, and remote sensing and timing. Each chapter is written by international experts and amply illustrated with figures and photographs, making the book an invaluable resource for scientists, engineers, students and institutions alike.

This book explores the significant challenges in sustaining and upgrading The Global Positioning System (GPS). The GPS provides positioning, navigation, and timing data to users world-wide, and has become essential to U.S. national security and a key tool in an expanding array of public service and commercial applications at home and abroad. GPS is integrated into nearly every facet of U.S. military operations, and the number of civil users is increasing. Other countries are now developing their own independent global navigation satellite systems that could offer capabilities that are comparable, if not superior to GPS. The U.S. government, which plans to invest more than $5.8 billion from 2009 through 2013 in the GPS space and ground control segments currently under development, provides GPS service free of charge. The Department of Defense (DoD) develops and operates GPS, and an interdepartmental committee manages the U.S. space-based positioning, navigation and timing infrastructure, which includes GPS. This book looks at the global economic and national security importance of GPS, the ongoing GPS modernisation effort and the international efforts to develop new systems.