Global Positioning System

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.Table of ContentsFront MatterExecutive SummaryTASK 1Recommendations that Enhance GPS Performance for Civil and Commercial UsersRecommendations that Enhance GPS Performance for All Users (Civil, Commercial, and Military)Improvement Implementation StrategyTASK 3THE TASKJOINT STUDY APPROACHMAJOR ISSUES AND CONSIDERATIONSGPS PROGRAM OVERVIEWGPS TECHNICAL OVERVIEWINTRODUCTIONGPS MILITARY APPLICATIONSCurrent and Future Applications and RequirementsAccuracy and IntegrityAnti-Jam and Anti-Spoof CapabilityGPS AVIATION APPLICATIONSCurrent and Future Applications and RequirementsResistance to Radio Frequency InterferenceOperational ProceduresMARITIME USE OF GPSCurrent and Future Applications and RequirementsAssociated TechnologiesSelective AvailabilityFindingsCurrent and Future Applications and RequirementsAccuracy Versus Other RequirementsFindingsCurrent and Future Applications and RequirementsChallenges to Full GPS UtilizationGPS EARTH SCIENCE APPLICATIONSOceanographyAirborne GeophysicsAccuracy RequirementsOceanographyFindingsCurrent and Future Applications and RequirementsTime SynchronizationSPACECRAFT USES OF GPSOrbit DeterminationLaunch and Re-entry Vehicle GuidanceSignal VisibilitySUMMARYINTRODUCTIONAccuracySELECTIVE AVAILABILITY AND ANTI-SPOOFINGSelective AvailabilityMilitary Utility of SAImpact of SA on GPS User Equipment Manufacturers and U.S. CompetitivenessImpact of SA on Civil UsersFindings and RecommendationsImpact of A-S on Military UsersFindings and RecommendationsSIGNAL STRUCTURE MODIFICATIONS TO REDUCE ATMOSPHERIC DELAY ERRORGuidelines and Technical ConsiderationsNew Signal Structure OptionsOption 2: Narrow-Band L4 SignalIncreased AccuracyReduction of Receiver Noise and Multipath ErrorsFindings and RecommendationsRecommended Upgrades to the Operational Control SegmentAccuracy ImprovementsOverall System ImprovementsPlanned Block IIR OperationAccuracy Improvements by Incorporating Satellite Ranging Data into Ground SolutionGround-Based Integrity ImprovementsRapid, Direct Y-Code AcquisitionInertial Aiding ImprovementsSignal Processing ImprovementsImproved L2 Ionospheric CorrectionPossible Interim Operational ProceduresIMPROVEMENT IMPLEMENTATION STRATEGYUse of a 24-Satellite Ensemble ClockReduced Satellite Clock Errors Through Use of Improved ClocksSatellite-Based Integrity MonitoringCross-Correlation Type Y-Codeless ReceiversY-Code Tracking PPS ReceiversWide-Band Signals at High FrequencySpot BeamsGPS Transmit Antenna CalibrationImproved L1 Signal Reception at Angles Below the Earth's HorizonAppendix B Abbreviated Committee Biographies ORIGINS AND DEVELOPMENT OF THE NAVSTAR GPS PROGRAMDepartment of DefenseDepartment of TransportationThe Federal Radionavigation PlanGPS TECHNICAL OVERVIEWSpace SegmentOperational Control SegmentUser EquipmentGPS Signal Characteristics and Operational ConceptsSelective Availability and Other Positioning ErrorsAtmospheric ErrorReceiver ErrorsAvailabilityResistance to RF InterferenceDifferential GPSCarrier Phase (Interferometric) GPSReceiver Autonomous Integrity Monitoring (RAIM)Combined Use of GPS and GLONASSGPS and Loran-CPERMANENT DIFFERENTIAL GPS AUGMENTATIONSFAA Wide-Area and Local-Area DGPS ConceptsNOAA Continuously Operated Reference StationsMaritime DGPS ServicesInmarsatRacal SurveyACCQPOINTDifferential Corrections Inc.Appendix D Accuracy Definitions And Mathematical RelationshipsAppendix E Report From Mr. Michael Dyment, Booz Allen & Hamilton Appendix F Report From Dr. Young Lee, The MITRE CorporationEFFECT OF ELIMINATING SELECTIVE AVAILABILITY (SA): IMPACT ON RAIMAppendix G Increased Bandwidth Performance AnalysisAppendix H Signal Structure OptionsOPTION 6OPTION 9Appendix I Report From Mr. Melvin Barmat, Jansky/Barmat Telecommunications, Inc.Appendix J Selective Denial of Civilian GPS Signals by the Military OLD TECHNOLOGY (100,000 GATE ASIC)DISCUSSIONAppendix L Enhanced Signal Structures for the MilitarySCENARIO 1: UNAIDED Y-CODE BANDWIDTH SIGNAL WITH A STANDARD ANTENNASCENARIO 5: AIDED WIDE BANDWIDTH STANDARD ANTENNASCENARIO 7: AIDED WIDE BANDWIDTH WITH NULLING AND BEAM-FORMING ANTENNAAnalysisAnalysis