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.
- The Global Positioning System: A Shared National Asset
- Copyright
- Acknowledgements
- Preface
- Contents
- Acronyms and Abbreviations
- Executive Summary
- TASK 1
- TASK 2
- Recommendations that Enhance GPS Performance for Civil and Commercial Users
- Recommendations that Enhance GPS Performance for Military Users
- Recommendations that Enhance GPS Performance for All Users (Civil, Commercial, and Military)
- Improvement Implementation Strategy
- TASK 3
- 1 Introduction
- THE TASK
- JOINT STUDY APPROACH
- National Research Council Study Approach
- MAJOR ISSUES AND CONSIDERATIONS
- REPORT ORGANIZATION
- GPS PROGRAM OVERVIEW
- GPS TECHNICAL OVERVIEW
- 2 GPS Applications and Requirements
- INTRODUCTION
- GPS MILITARY APPLICATIONS
- Current and Future Applications and Requirements
- Challenges to Full GPS Utilization
- Accuracy and Integrity
- Anti-Jam and Anti-Spoof Capability
- Findings
- GPS AVIATION APPLICATIONS
- Current and Future Applications and Requirements
- Challenges to Full Utilization of GPS
- Selective Availability and Anti-Spoofing
- Resistance to Radio Frequency Interference
- Operational Procedures
- Findings
- MARITIME USE OF GPS
- Current and Future Applications and Requirements
- Challenges to Full Utilization of GPS
- Associated Technologies
- Selective Availability
- Integrity
- Availability and Radio Frequency Interference
- Findings
- LAND TRANSPORTATION APPLICATIONS
- Current and Future Applications and Requirements
- Challenges to Full GPS Utilization
- Accuracy Versus Other Requirements
- The Cost of Integrated Systems
- Findings
- MAPPING, GEODESY, AND SURVEYING APPLICATIONS
- Current and Future Applications and Requirements
- Challenges to Full GPS Utilization
- Findings
- GPS EARTH SCIENCE APPLICATIONS
- Current and Future Applications and Requirements
- Meteorology
- Oceanography
- Geodynamics
- Airborne Geophysics
- Accuracy Requirements
- Challenges to Full GPS Utilization
- Meteorology
- Oceanography
- Geodynamics
- Airborne Geophysics
- Findings
- GPS TIMING AND TELECOMMUNICATIONS APPLICATIONS
- Current and Future Applications and Requirements
- Challenges to Full GPS Utilization
- Time Transfer
- Time Synchronization
- Findings
- SPACECRAFT USES OF GPS
- Current and Future Applications and Requirements
- Orbit Determination
- Attitude Determination
- Launch and Re-entry Vehicle Guidance
- Challenges to Full GPS Utilization
- Orbit Determination and Orbital Positioning
- Attitude Determination
- Signal Visibility
- Findings
- SUMMARY
- 3 Performance Improvements to the Existing GPS Configuration
- INTRODUCTION
- CURRENT GPS PERFORMANCE
- Accuracy
- Integrity and Availability
- SELECTIVE AVAILABILITY AND ANTI-SPOOFING
- Selective Availability
- Military Utility of SA
- Impact of SA on GPS User Equipment Manufacturers and U.S. Competitiveness
- Impact of SA on Civil Users
- Findings and Recommendations
- Anti-Spoofing
- Impact of A-S on Military Users
- Impact of A-S on Civil Users
- Findings and Recommendations
- SIGNAL STRUCTURE MODIFICATIONS TO REDUCE ATMOSPHERIC DELAY ERROR
- Guidelines and Technical Considerations
- New Signal Structure Options
- Option 1: Wide-Band L4 Signal
- Option 2: Narrow-Band L4 Signal
- Additional Considerations
- Improvements Anticipated from Adding L4
- Increased Accuracy
- Additional Benefits of L4
- Reduction of Receiver Noise and Multipath Errors
- Findings and Recommendations
- PERFORMANCE IMPROVEMENTS TO THE GPS OPERATIONAL CONTROL SEGMENT AND SATELLITE CONSTELLATION
- Current Status of the Operational Control Segment and Planned Upgrades
- Recommended Upgrades to the Operational Control Segment
- Accuracy Improvements
- Overall System Improvements
- Planned Block IIR Operation
- Suggested Improvements Using the Autonomous Ranging and Crosslink Communication Capability
- Accuracy Improvements by Incorporating Satellite Ranging Data into Ground Solution
- Satellite Health Monitoring to Improve System Reliability and Availability
- Ground-Based Integrity Improvements
- PERFORMANCE IMPROVEMENTS TO ENHANCE THE MILITARY USE OF GPS
- Recommended Technical Improvements to Military User Equipment
- Rapid, Direct Y-Code Acquisition
- Antenna Subsystem Improvements
- Inertial Aiding Improvements
- Signal Processing Improvements
- Improved L2 Ionospheric Correction
- Possible Interim Operational Procedures
- IMPROVEMENT IMPLEMENTATION STRATEGY
- 4 Technical Enhancements for Future Consideration
- GPS IMPROVEMENTS TO IMPROVE OVERALL PERFORMANCE
- Use of a 24-Satellite Ensemble Clock
- Reduced Satellite Clock Errors Through Use of Improved Clocks
- Satellite-Based Integrity Monitoring
- Increased L2 Signal Strength
- Cross-Correlation Type Y-Codeless Receivers
- L2 Squaring Y-Codeless Receivers
- Y-Code Tracking PPS Receivers
- MILITARY ENHANCEMENTS
- Block IIF Signal Structure Military Enhancements
- Wide-Band Signals at High Frequency
- Spot Beams
- ENHANCEMENTS FOR HIGH-PRECISION USERS
- GPS Transmit Antenna Calibration
- Knowledge of Spacecraft Characteristics
- Improved L1 Signal Reception at Angles Below the Earth's Horizon
- Appendix B Abbreviated Committee Biographies
- Appendix C Overview Of The Global Positioning System And Current Or Planned Augmentations
- ORIGINS AND DEVELOPMENT OF THE NAVSTAR GPS PROGRAM
- GPS POLICY, MANAGEMENT, AND OPERATIONS
- Department of Defense
- Department of Transportation
- The Federal Radionavigation Plan
- GPS TECHNICAL OVERVIEW
- Space Segment
- Operational Control Segment
- User Equipment
- GPS Signal Characteristics and Operational Concepts
- Selective Availability and Other Positioning Errors
- Atmospheric Error
- Clock and Ephemeris Error
- Multipath Errors
- Receiver Errors
- Dilution of Precision
- IMPROVING THE CAPABILITIES OF GPS
- Integrity
- Availability
- Continuity of Service
- Resistance to RF Interference
- Augmentations and Enhancements
- Differential GPS
- Carrier Phase (Interferometric) GPS
- Pseudolites
- Receiver Autonomous Integrity Monitoring (RAIM)
- Combined Use of GPS and GLONASS
- GPS/Inertial Navigation System (INS) Integration
- GPS and Loran-C
- PERMANENT DIFFERENTIAL GPS AUGMENTATIONS
- U.S. Government-Supported Differential GPS
- FAA Wide-Area and Local-Area DGPS Concepts
- U.S. Coast Guard DGPS Service
- NOAA Continuously Operated Reference Stations
- State and Local Government DGPS
- Differential Systems Supported by Foreign Governments and International Organizations
- Maritime DGPS Services
- International Participation in the FAA's WAAS
- Inmarsat
- The International GPS Service for Geodynamics
- Racal Survey
- John E. Chance & Associates, Inc. (A member of the Fugro Group of Companies)
- ACCQPOINT
- Differential Corrections Inc.
- Appendix D Accuracy Definitions And Mathematical Relationships
- Appendix E Report From Mr. Michael Dyment, Booz • Allen & Hamilton
- Appendix F Report From Dr. Young Lee, The MITRE Corporation
- EFFECT OF ELIMINATING SELECTIVE AVAILABILITY (SA): IMPACT ON RAIM
- Appendix G Increased Bandwidth Performance Analysis
- Appendix H Signal Structure Options
- OPTIONS 1 AND 2
- OPTIONS 3 AND 4
- OPTION 5
- OPTION 6
- OPTION 7
- OPTION 8
- OPTION 9
- Appendix I Report From Mr. Melvin Barmat, Jansky/Barmat Telecommunications, Inc.
- Appendix J Selective Denial of Civilian GPS Signals by the Military
- Appendix K Direct Y-Code Acquisition
- OLD TECHNOLOGY (100,000 GATE ASIC)
- CURRENT TECHNOLOGY (500,000 GATE ASIC)
- DISCUSSION
- Appendix L Enhanced Signal Structures for the Military
- SCENARIO 1: UNAIDED Y-CODE BANDWIDTH SIGNAL WITH A STANDARD ANTENNA
- SCENARIO 2: AIDED Y-CODE BANDWIDTH WITH A STANDARD ANTENNA
- SCENARIO 3: AIDED Y-CODE BANDWIDTH WITH NULLING ANTENNA
- SCENARIO 4: UNAIDED WIDE BANDWIDTH WITH STANDARD ANTENNA
- SCENARIO 5: AIDED WIDE BANDWIDTH STANDARD ANTENNA
- SCENARIO 6: AIDED WIDE BANDWIDTH WITH MINIATURIZED NULLING ANTENNA
- SCENARIO 7: AIDED WIDE BANDWIDTH WITH NULLING AND BEAM-FORMING ANTENNA
- Appendix M Accuracy of a 14-Satellite Ensemble Versus a 24-Satellite Ensemble