UpdateonGNSSPerformanceMonitoring
YoazBar-Sever([email protected])
JetPropulsionLaboratoryCaliforniaInstituteofTechnology
1YEB- June2017
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15YearsofJPLGPSPerformanceMonitoringfortheAirForce
InitiatedbyAerospaceCorporationfollowingtheSVN22eventofNovember5,2002
TheJPLGPSperformancemonitoringservicewasjointlydevelopedbyJPLandAerospace,withinputfromthe2SOPSoperators• Fundedinrecentyearsby2SOPSoperationalbudget• Continuouslyrefinedandaugmentedwithadditionalcapabilities• Usetrackingdatafrom80+sitesintheGlobalDifferentialGPS(GDGPS)network• GDGPSreal-timeorbitandclocksolutionsareusedasTruth
Monitorkeyperformancemetricsofthebroadcastephemerisandthenavigationsignals• Userrangeaccuracy,duetobroadcastorrangingsignal• Correctnessofkeybroadcastparameters• Satelliteobservabilityassessment• 30secondlatency
GPS-basedarrival-timesystemonatraintraversingtheEasternseaboardsawextraordinarypositionerrors.
Source:J.Langer,Aerospace,April2003
TheactiveRubidiumclockontheBlockIIAspacecraftexperiencedafrequencyjumpwhilethesatellitewasnotmonitoredbytheOCSfornearly2hours
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SnapshotoftheGDGPSCNAVMonitoringWebPage
Recently-addedcapabilities:• CNAVmonitoringonL2andL5• UTCmodel(aftertheJan2016event)
• DifferentialCodeBiasesmonitoring• GNSStimetransferparameters(in2018)
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SnapshotoftheGDGPSCNAVMonitoringWebPage(contd.)
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MonitoringinSupportofSingle-FrequencyUsers
LeveragingJPL’sionosphericexpertiseanddenseglobalnetwork
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MonitoringandUploadofInter-FrequencyBiases
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
10.00
10 20 30 40 50 60 70 80
Tgd
(ns)
SVN
Three Tgd EstimatesJPL Tgd Estimate 2017/04 (ns)JPL Tgd Estimate 2017/01 (ns)Previous JPL Tgd Estimate 2016/10 (ns)
JPL’sTgd estimatesarebeingbroadcastbyGPS;Updatedquarterlyandonchange
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TheFoundation:ExtremelyRedundantGlobalReal-TimeTrackingNetwork
80+globaltrackingsitesdeployed,controlled,operated,andmaintainedbyJPL’sGDGPSSystem• HardwareandsoftwarefullyownedandcontrolledbyJPL• Decadesofsitestability,quality,andcontinuity• 25-foldobservationredundancy,onaverage,enablestrongmajorityvotingschemes
Hundredsofcontributedsitesoperatedbyavarietyofpartners,U.S.andforeignagencies(e.g.,NSF,BKG,GA)provideadditionallevelofredundancyanddensityofcoverage
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CSM,OnceAgainJPLalreadymonitorsandreportsallthekeynavigationmetricsoftheGPScivilsignals
JPLalreadypossessesallthedataneededtoverify90%oftheCivilMonitoringPerformanceSpecifications(CMPS)
JPLproposedtomonitor98%oftheCMPSwithinayear• LeveragingthesignificantNASAandUSAFinvestmentintheGDGPSSystem• PNTABrecommendedusingthecost-effectiveGDGPSsystemforCSM(Parkinson,2013)• TheproposalwasanalyzedbytheFAA2014CSMTradeStudyTeamandfoundattractive
Refinedproposal(workedwithFAA)submittedtoFAAinOctober2015.Thensilence.
WecouldhavehadCSM15yearsago!
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Real-TimeGNSSPerformanceMonitoringAvailablenowGDGPSismonitoringthecivilsignalsfromGLONASS,BeiDou,andGalileo.Soon,QZSS• IRNSSmonitoringisbeingassessed• 100%redundantglobalcoverage
HighaccuracyrealtimeorbitandclocksolutionsprovidesomebenefitsrelativetoGPS-onlyincertainapplications• e.g.Earthquakemonitoring:
GDGPS Real-Time Natural Hazard Monitoring
10YEB- June2017
Displacementmonitoringfor200+sitesathttps://ga.gdgps.net
Real-TimedetectionoftsunamiionosphericdisturbanceswithGNSSgroundtracking(Savastano etal.,Nature,2017)
ConclusionsExistingandprovenGDGPStrackingnetworks,technologies,andoperationalcapabilitiescanprovideeffectiveandlowcostGPScivilsignalmonitoring
JPL’sGDGPSSystemalreadytracksandmonitorsGLONASS,BeiDou,andGalileoonaglobalscale• CanbeusedtoalleviateconcernsintheU.S.aboutincorporatingGNSSsignalsintocertain
regulatedservices,suchasE-911geolocation• ThesystemisalreadybeingusedcommerciallytoprovideAssistedGNSSservicestomillions
ofmobileusers
11YEB- June2017
Prototypesystemandtestbed forNextGenerationGPSControlSegment(OCX)
Triple Hot Redundant Operation CentersReal-Time Tracking Network
(200+ sites)
Measurements Products, Services
The Global Differential GPS (GDGPS) SystemProviding mission-critical, real-time services, 24/7, since 2000
FullGNSScapabilities:GPS,GLONASS,BeiDou,Galileo
PersonalGeolocation
PrecisionIndustrialPositioning
GNSSMonitoring
Time-criticalenvironmentalmonitoringservices
Space weather monitoring
Repeat path interferometry with UAV-SAR
GNSS navigation data for Radio Occultations
Earthquake monitoring and tsunami prediction
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