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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.

Suggested Citation

National Research Council. 1995. The Global Positioning System: A Shared National Asset. Washington, DC: The National Academies Press. https://doi.org/10.17226/4920.

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Publication Info

284 pages |  8.5 x 11 | 

ISBNs: 
  • Paperback:  978-0-309-05283-2
  • Ebook:  978-0-309-17644-6
DOI: https://doi.org/10.17226/4920
Chapters skim
Front Matter i-xx
Executive Summary 1-1
TASK 1 2-6
Recommendations that Enhance GPS Performance for Civil and Commercial Users 7-7
Recommendations that Enhance GPS Performance for All Users (Civil, Commercial, and Military) 8-9
Improvement Implementation Strategy 10-11
TASK 3 12-12
THE TASK 13-13
JOINT STUDY APPROACH 14-14
MAJOR ISSUES AND CONSIDERATIONS 15-15
GPS PROGRAM OVERVIEW 16-16
GPS TECHNICAL OVERVIEW 17-18
INTRODUCTION 19-19
GPS MILITARY APPLICATIONS 20-20
Current and Future Applications and Requirements 21-21
Accuracy and Integrity 22-24
Anti-Jam and Anti-Spoof Capability 25-25
GPS AVIATION APPLICATIONS 26-26
Current and Future Applications and Requirements 27-29
Resistance to Radio Frequency Interference 30-30
Operational Procedures 31-31
MARITIME USE OF GPS 32-32
Current and Future Applications and Requirements 33-34
Associated Technologies 35-35
Selective Availability 36-36
Findings 37-37
Current and Future Applications and Requirements 38-40
Accuracy Versus Other Requirements 41-41
Findings 42-42
Current and Future Applications and Requirements 43-44
Challenges to Full GPS Utilization 45-45
GPS EARTH SCIENCE APPLICATIONS 46-46
Oceanography 47-47
Airborne Geophysics 48-48
Accuracy Requirements 49-49
Oceanography 50-50
Findings 51-51
Current and Future Applications and Requirements 52-54
Time Synchronization 55-55
SPACECRAFT USES OF GPS 56-56
Orbit Determination 57-57
Launch and Re-entry Vehicle Guidance 58-59
Signal Visibility 60-60
SUMMARY 61-66
INTRODUCTION 67-67
Accuracy 68-69
SELECTIVE AVAILABILITY AND ANTI-SPOOFING 70-70
Selective Availability 71-71
Military Utility of SA 72-77
Impact of SA on GPS User Equipment Manufacturers and U.S. Competitiveness 78-78
Impact of SA on Civil Users 79-81
Findings and Recommendations 82-83
Impact of A-S on Military Users 84-84
Findings and Recommendations 85-85
SIGNAL STRUCTURE MODIFICATIONS TO REDUCE ATMOSPHERIC DELAY ERROR 86-86
Guidelines and Technical Considerations 87-87
New Signal Structure Options 88-88
Option 2: Narrow-Band L4 Signal 89-89
Increased Accuracy 90-90
Reduction of Receiver Noise and Multipath Errors 91-96
Findings and Recommendations 97-97
Recommended Upgrades to the Operational Control Segment 98-98
Accuracy Improvements 99-105
Overall System Improvements 106-107
Planned Block IIR Operation 108-108
Accuracy Improvements by Incorporating Satellite Ranging Data into Ground Solution 109-109
Ground-Based Integrity Improvements 110-110
Rapid, Direct Y-Code Acquisition 111-112
Inertial Aiding Improvements 113-113
Signal Processing Improvements 114-114
Improved L2 Ionospheric Correction 115-115
Possible Interim Operational Procedures 116-116
IMPROVEMENT IMPLEMENTATION STRATEGY 117-122
Use of a 24-Satellite Ensemble Clock 123-123
Reduced Satellite Clock Errors Through Use of Improved Clocks 124-124
Satellite-Based Integrity Monitoring 125-125
Cross-Correlation Type Y-Codeless Receivers 126-126
Y-Code Tracking PPS Receivers 127-127
Wide-Band Signals at High Frequency 128-131
Spot Beams 132-132
GPS Transmit Antenna Calibration 133-133
Improved L1 Signal Reception at Angles Below the Earth's Horizon 134-138
Appendix B Abbreviated Committee Biographies 139-144
ORIGINS AND DEVELOPMENT OF THE NAVSTAR GPS PROGRAM 145-145
Department of Defense 146-146
Department of Transportation 147-147
The Federal Radionavigation Plan 148-149
GPS TECHNICAL OVERVIEW 150-150
Space Segment 151-152
Operational Control Segment 153-153
User Equipment 154-154
GPS Signal Characteristics and Operational Concepts 155-157
Selective Availability and Other Positioning Errors 158-159
Atmospheric Error 160-160
Receiver Errors 161-161
Availability 162-162
Resistance to RF Interference 163-163
Differential GPS 164-164
Carrier Phase (Interferometric) GPS 165-165
Receiver Autonomous Integrity Monitoring (RAIM) 166-166
Combined Use of GPS and GLONASS 167-167
GPS and Loran-C 168-168
PERMANENT DIFFERENTIAL GPS AUGMENTATIONS 169-169
FAA Wide-Area and Local-Area DGPS Concepts 170-170
NOAA Continuously Operated Reference Stations 171-171
Maritime DGPS Services 172-172
Inmarsat 173-173
Racal Survey 174-174
ACCQPOINT 175-175
Differential Corrections Inc. 176-176
Appendix D Accuracy Definitions And Mathematical Relationships 177-178
Appendix E Report From Mr. Michael Dyment, Booz Allen & Hamilton 179-200
Appendix F Report From Dr. Young Lee, The MITRE Corporation 201-203
EFFECT OF ELIMINATING SELECTIVE AVAILABILITY (SA): IMPACT ON RAIM 204-212
Appendix G Increased Bandwidth Performance Analysis 213-214
Appendix H Signal Structure Options 215-217
OPTION 6 218-218
OPTION 9 219-220
Appendix I Report From Mr. Melvin Barmat, Jansky/Barmat Telecommunications, Inc. 221-248
Appendix J Selective Denial of Civilian GPS Signals by the Military 249-252
OLD TECHNOLOGY (100,000 GATE ASIC) 253-253
DISCUSSION 254-254
Appendix L Enhanced Signal Structures for the Military 255-255
SCENARIO 1: UNAIDED Y-CODE BANDWIDTH SIGNAL WITH A STANDARD ANTENNA 256-256
SCENARIO 5: AIDED WIDE BANDWIDTH STANDARD ANTENNA 257-257
SCENARIO 7: AIDED WIDE BANDWIDTH WITH NULLING AND BEAM-FORMING ANTENNA 258-262
Analysis 263-263
Analysis 264-264

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