The Global Positioning System: A Shared National Asset (1995)
Chapter: Front Matter
NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competencies and with regard for appropriate balance.
This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences.
The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Robert M. White is president of the National Academy of Engineering.
The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Kenneth I. Shine is president of the Institute of Medicine.
The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. Robert M. White are chairman and vice-chairman, respectively, of the National Research Council.
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COMMITTEE ON THE FUTURE OF THE GLOBAL POSITIONING SYSTEM
Laurence J. Adams, Chair,
Martin Marietta Corporation (Ret.), Consultant, Potomac, Maryland
Penina Axelrad,
Colorado Center for Astrodynamics Research, University of Colorado, Boulder, Colorado
John D. Bossler,
Center for Mapping, Ohio State University, Columbus, Ohio
Ronald Braff,
Center for Advanced Aviation, System Development, MITRE Corporation, McLean, Virginia
A. Ray Chamberlain,
American Trucking Association, Inc., Alexandria, Virginia
Ruth M. Davis,
Pymatuning Group, Inc., Alexandria, Virginia
John V. Evans,
COMSAT Laboratories, COMSAT Corporation, Clarksburg, Maryland
John S. Foster,
TRW Inc. (Retired), Redondo Beach, California
Emanuel J. Fthenakis,
Fairchild Industries (Ret.), Potomac, Maryland
J. Freeman Gilbert,
Institute of Geophysics and Planetary Physics, University of California, San Diego, La Jolla, California
Ralph H. Jacobson,
The Charles Stark Draper Laboratory, Inc., Cambridge, Massachusetts
Keith D. McDonald,
Sat Tech Systems, Arlington, Virginia
Irene C. Peden,
University of Washington, (Retired) Seattle, Washington
James W. Sennott,
Department of Electrical and Computer Engineering and Technology, Bradley University, Peoria, Illinois
Joseph W. Spalding,
U.S. Coast Guard Research and Development Center, Groton, Connecticut
Lawrence E. Young,
Jet Propulsion Laboratory, Pasadena, California
Staff
Archie Wood, Executive Director,
Commission on Engineering and Technical Systems
JoAnn C. Clayton, Director,
Aeronautics and Space Engineering Board
Allison C. Sandlin, Study Director
David A. Turner, Study Consultant
Cristellyn Banks, Project Assistant
COMMISSION ON ENGINEERING AND TECHNICAL SYSTEMS
Albert R. C.
Westwood, Research and Exploratory Technology, Sandia National Laboratories, Albuquerque, New Mexico,
Chair
Naomi F. Collins,
NAFSA: Association of International Educators, Washington D.C.
Nancy R. Connery,
Woolwich, Maine
Richard A. Conway,
Union Carbide Corporation, South Charleston, West Virginia
Samuel C. Florman,
Kreisler Borg Florman Construction Company, Scarsdale New York
Trevor O. Jones,
Libbey-Owens-Ford Company, Cleveland, Ohio
Nancy G. Leveson,
Department of Computer Science and Engineering, University of Washington, Seattle, Washington
Alton D. Slay,
Slay Enterprises, Inc., Warrenton, Virginia
James J. Solberg,
Purdue University, West Lafayette, Indiana
Barry M. Trost,
Chemistry Department, Stanford University, Stanford, California
George L. Turin,
Berkeley, California
William C. Webster,
College of Engineering, Berkeley, California
Deborah A. Whitehurst,
Arizona Community Foundation, Phoenix Arizona
Robert V. Whitman,
Lexington, Massachusetts
Staff
Archie Wood, Executive Director,
Commission on Engineering and Technical Systems
Acknowledgements
The National Research Council's Committee on the Future of the Global Positioning System would like to thank all the individuals who participated in this study, especially Mr. Jules McNeff, Major Lee Carrick, Major Matthew Brennen, Lieutenant Brian Knitt, Captain Earl Pilloud, Captain Christopher Shank, Lieutenant Colonel Donald Latterman, Major Al Mason, Mr. John Clark, Mr. Scott Feairheller, Mr. Terry McGurn, Mr. Jim Graf, Mr. John Hrinkevich, and Mr. Jon Schnabel who arranged briefings and responded to committee requests throughout the study. In addition, Mr. Peter Serini and Mr. George Wiggers served as the committee's liaisons with the Department of Transportation and also were helpful in obtaining relevant information and arranging briefings. The NRC committee also benefited from the work of numerous previous study groups, and considered their recommendations. In addition to the many informative briefings, the committee requested a large number of written responses from receiver manufacturers and many others concerning various issues. The NRC committee wishes to thank all of the contributors for their cooperation in providing existing information and in researching some of the issues that arose. The committee also would like to acknowledge Mr. Michael Dyment of Booz•Allen & Hamilton, who conducted an analysis of the economic impact of the removal of Selective Availability on the differential GPS market; Mr. Melvin Barmat of Jansky/Barmat Telecommunications, Inc., who performed an analysis of L-band frequency availability; and Dr. Young Lee of the MITRE Corporation, who conducted an analysis of the effect of improved accuracy on Receiver Autonomous Integrity Monitoring. A complete list of study participants is given in Appendix A.
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Preface
The Global Positioning System (GPS) was originally designed primarily to provide highly accurate radionavigation capability to U.S. military forces, while also providing an unencrypted signal of degraded accuracy to civilian users. As the system developed, civil usage expanded rapidly and the number of civilian users now greatly exceeds the number of military users. The timing, velocity, and positioning information provided by GPS is being used for a growing number of new, innovative applications that could not have been foreseen by the original system designers. Because of its widespread use by both the military and civilians, GPS has truly emerged as a dual-use system.
Recognizing that the continued existence of GPS as a dual-use system clearly requires some trade-offs between civilian utility and national security, Congress requested a joint study by the National Academy of Sciences and the National Academy of Public Administration (NAPA) on the Department of Defense's Global Positioning System (GPS). The National Academy of Sciences was asked to recommend technical improvements and augmentations that could enhance military, civilian, and commercial use of the system. The National Academy of Public Administration was asked to address GPS management and funding issues, including commercialization, governance, and international participation. To conduct its part of the study, the National Academy of Sciences established an expert committee through the National Research Council (NRC), the operating arm of the National Academy of Sciences and the National Academy of Engineering.
This report provides the results of the technical portion of the study conducted by the National Research Council's Committee on the Future of the Global Positioning System. Portions of this report (for example, Chapters 3, 4, and some of the appendices) also are included in the joint NRC/NAPA report, The Global Positioning System—Charting the Future, which contains the complete results of the NAPA portion of the study.
In examining future enhancements to the GPS system, the NRC committee endeavored to balance the features that would enhance civil applications against the clear requirement to maintain the military integrity of the system. The recommendations in the report were intended to meet this criterion.
LAURENCE J. ADAMS, CHAIR
COMMITTEE ON THE FUTURE OF
THE GLOBAL POSITIONING SYSTEM
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List of Figures
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Figure 1 |
Current plan for satellite replacement. (Courtesy of the GPS Joint Program Office) |
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Figure 3-1 |
DGPS coverage provided by commercially available systems, including Skyfix and Sercel. (Courtesy of the National Air Intelligence Center) |
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Figure 3-2 |
DGPS coverage provided by the planned FAA WAAS (Wide-Area Augmentation System). Source: Innovative Solutions International, Inc. presentation at the National Technical Meeting of the Institute of Navigation Meeting, Anaheim, California, January 1995. |
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Figure 3-3 |
Position estimates from GPS and GLONASS obtained from measurement snapshots taken 1 minute apart over an entire day. Position from (a) GPS with SA off, (b) GPS with SA on, (c) GLONASS, and (d) GPS + GLONASS. (Courtesy of MIT Lincoln Laboratory) |
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Figure 3-4 |
Horizontal scatter plot of 42 meters CEP (100 meters, 2 drms) with SA at its current level and horizontal scatter plot of approximately 10 meters CEP (24 meters, 2 drms) without SA. (Figure Courtesy of Mr. Jules McNeff, Office of the Assistant Secretary of Defense, C3I) |
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Figure 3-5 |
Approximate stand-alone horizontal SPS accuracy, 2 drms resulting from recommended improvements and enhancements. |
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Figure 3-6 |
Current plan for satellite replacement. (Courtesy of the GPS Joint Program Office) |
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Figure 4-1 |
Wide-band GPS with a 100-watt jammer. |
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Figure 4-2 |
Wide-band GPS with a 10-kilowatt jammer. |
List of Tables
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Table 2-1 |
Military Aviation and Precision-Guided Munitions Applications and Requirements |
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Table 2-2 |
Naval Applications and Requirements |
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Table 2-3 |
Military Land Applications and Requirements |
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Table 2-4 |
GPS Performance Requirements for Aviation Applications |
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Table 2-5 |
Requirements for Maritime Applications |
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Table 2-6 |
Land Transportation Requirements |
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Table 2-7 |
Current and Future GPS Requirements for GIS, Mapping, Surveying, and Geodesy |
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Table 2-8 |
GPS Earth Science Requirements |
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Table 2-9 |
Timing and Telecommunications Requirements |
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Table 2-10 |
Requirements for GPS Spacecraft Applications |
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Table 2-11 |
Summary of Military Applications with Accuracy Requirements Unmet by the GPS PPS as Currently Specified |
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Table 2-12 |
Summary of Civilian Applications with Accuracy Requirements of 100 Meters or Greater (currently achievable with the basic GPS SPS) |
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Table 2-13 |
Summary of Civilian Accuracy Requirements Between 25 and 100 Meters |
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Table 2-14 |
Summary of Civilian Accuracy Requirements Between 10 and 25 Meters |
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Table 2-15 |
Summary of Civilian Accuracy Requirements Between 1 and 10 Meters |
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Table 2-16 |
Summary of Submeter Civilian Accuracy Requirements |
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Table 3-1 |
Observed GPS Positioning Errors with Typical SPS and PPS Receivers |
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Table 3-2 |
SA Errors from DOD/DOT Signal Specification Issues Technical Group |
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Table 3-3 |
The Effect of Eliminating SA on GPS SPS Stand-Alone Horizontal Accuracy |
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Table 3-4 |
Effect of SA Removal on RAIM Availability for Aviation Applications |
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Table 3-5 |
Elimination of Ionospheric Error by the Addition of Another Frequency |
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Table 3-6 |
Effect of Reduced Ionospheric Error by the Addition of Another Frequency and Additional Improvements Obtained with Using a More Advanced SPS Receiver |
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Table 3-7 |
Effect of Using a More Advanced PPS Receiver on Stand-Alone Accuracy |
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Table 3-8 |
Effect of SA Removal and Dual-Frequency Capability on RAIM Availability for Aviation Applications |
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Table 3-9 |
Reduction of Combined Clock and Ephemeris Errors |
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Table 3-10 |
Impact of Reduced Clock and Ephemeris Error on SPS Stand-Alone Accuracy |
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Table 3-11 |
Impact of Reduced Clock and Ephemeris Error on PPS Stand-Alone Accuracy |
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Table 3-12 |
Effect of SA Removal, Dual-Frequency Capability and Reduced Clock and Ephemeris Errors on RAIM Availability for Aviation Applications |
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Table 3-13 |
Space Segment Enhancements |
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Table 3-14 |
Operational Control Segment Enhancements |
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Table 4-1 |
GPS Wide-Band Signal Augmentation Performance with a 100-Watt Jammer |
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Table 4-2 |
GPS Wide-Band Signal Augmentation Performance with a 10-Kilowatt Jammer |
Acronyms and Abbreviations
ADS
Automatic dependant surveillance
ANSI
American National Standards Institute
A-S
Anti-Spoofing
ASIC
Application Specific Integrated Circuit
ATM
Air Traffic Management
AVI
Automatic Vehicle Identification
AVL
Automatic Vehicle Location
BIPM
Bureau International des Poids et Measures
C/A
Coarse/Acquisition code
CDMA
Code Division Multiple Access
CEP
Circular Error Probable
CGS
Civil GPS Service
CGSIC
Civil GPS Service Interface Committee
CORS
Continuously Operating Reference Station
CRPA
Controlled Radiation (Reception) Patterned Antenna
dB
decibel
DGPS
Differential GPS
DMA
Defense Mapping Agency
DOD
Department of Defense
DOP
Dilution of Precision
DOT
Department of Transportation
drms
distance root mean square
DRVID
Differential Ranging Versus Integrated Doppler
ECDIS
Electronic Chart Display Information System
FAA
Federal Aviation Administration (part of DOT)
FDMA
Frequency Division Multiple Access
FHWA
Federal Highway Administration
FM
Frequency Modulation
FRA
Federal Railroad Administration
GIS
Geographic Information Systems
GHz
Gigahertz
GLONASS
Global Navigation Satellite System
GNSS
Global Navigation Satellite System
GPS
Global Positioning System
HDOP
Horizontal Dilution of Precision
Hz
Hertz (cycles per second)
IALA
International Association of Lighthouse Authorities
ICAO
International Civil Aviation Organization
IF
Intermediate Frequency
IGS
International GPS Service for Geodynamics
ILS
Instrument Landing System
IMO
International Maritime Organization
Inmarsat
International Maritime Satellite Organization
INS
Inertial Navigation System
ITS
Intelligent Transportation System
IVHS
Intelligent Vehicle Highway Systems
JCS
Joint Chiefs of Staff
JPO
Joint Program Office
J/S
Jammer-to-signal ratio
KHz
Kilohertz
L1
GPS L-band signal 1 (1575.42 MHz)
L2
GPS L-band signal 2 (1227.6 MHz)
L4
Proposed GPS L-band signal
L-band
L-band frequency (about 1-2 GHz)
LADGPS
Local Area Differential GPS
LORAN-C
Long-Range Navigation, Version C
MBS
Mobile Broadcast Service
MCS
GPS Master Control Station
MHz
Megahertz
ms
Millisecond
MOA
Memorandum of Agreement
NAPA
National Academy of Public Administration
NASA
National Aeronautics and Space Administration
NCA
National Command Authority
NDB
Nondirectional Beacon
NGS
National Geodetic Survey
NIST
National Institute of Standards and Technology
NOAA
National Oceanic and Atmospheric Administration
NRC
National Research Council
ns
nanosecond
NSA
National Security Agency
NTIA
National Telecommunications and Information Administration
OCS
Operational Control Segment
P-code
Precision code
PHE
Probability of Hazardous Error
PLGR
Precision Lightweight GPS Receiver
PMD
Probability of Missed Detection
P3I
Preplanned Product Improvement
PPS
Precise Positioning Service
PRN
Pseudorandom Noise
RAIM
Receiver Autonomous Integrity Monitoring
RDS
Radio Data System
RF
Radio Frequency
RFP
Request for Proposal
RISC
Reduced Instruction Set Computing
RNP
Required Navigation Performance
ROD
Relative Operating Distance
RTCA
Ratio Technical Commission for Aeronautics
RTCM
Radio Technical Commission for Maritime Services
SA
Selective Availability
SAIM
Satellite Autonomous Integrity Monitoring
S-band
Microwave frequency band, about 2-4 GHz
SEP
Spherical Error Probable
sigma
standard deviation (symbol: a)
SNR
Signal-to-Noise Ratio
SONET
Synchronized Optical Network
SPS
Standard Positioning Service
TACAN
Tactical Air Navigation
TAI
International Atomic Time
TCAS
Traffic Alert/Collision Avoidance System
TDMA
Time Division Multiple Access
TEC
Total Electron Content
TOD
Time of day
UERE
User Equivelent Range Error
UHF
Ultra High Frequency
USAF
United States Air Force
USCG
United States Coast Guard
USNO
United States Naval Observatory
UTC
Coordinated Universal Time
VDOP
Vertical Dilution of Precision
VHF
Very High Frequency
VLBI
Very Long Baseline Interferometry
VOR
VHF Omnidirectional Range
VOR/DME
VOR with Distance Measuring Equipment
VORTAC
combined VOR and TACAN
VTS
Vessel Traffic Services
WAAS
Wide Area Augmentation System
WADGPS
Wide Area Differential GPS
WGS
World Geodetic System
Y-code
Encrypted P-code
