GPS相关外文翻译.docx

GPS相关外文翻译.docx

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GPS相关外文翻译

第一篇中英文互译

外文原文

Recently,accordingtotherequirementsofsomeimportantGPSresearchsubjectsinthefieldsofGeodesy,Geophysics,Space-PhysicsandnavigationinChina,westudiedsystematicallyhowtocorrectingtheeffectsoftheionosphereonGPS,withhigh-precisionandaccuracy.Asthepartsofthemaincontributions,theresearchprojectsfocusmainlyonhowtoimproveGPSsurveyingbyreducingionosphericdelayfordual/singlefrequencykinematic/staticusers:

highaccuracycorrectionofionosphericdelayforsingle/dualfrequencyGPSusersontheearthandinspace,ChinaWAASionosphericmodelingandthetheoryandmethodofmonitoringofionosphereusingGPS. 

ThemaincontentsofthisPh.Dpaperconsistoftwoparts:

Fisrtpart---theoutlineofresearchbackgroundandthesystematicintroductionandsummarizationofthepreviousresearchresultsofthiswork.

Secondpart---themaincontributionandresearchresultsofthispaperarefocusedonasfollows:

（1）HowtousethemeasurementsofadualfrequencyGPSreceivertodeterminetheionosphericdelaycorrectionmodelforsinglefrequencyGPSofalocalrange;

（2）   HowtoseparatetheinstrumentalbiaseswiththeionosphericdelaysinGPSobservation;

（3）HowtoestablishalargerangegridionospheremodelandusetheGPSdataofChinesecrustmovementobservationnetworktoinvestigatethechangelawofionosphericTECof Chinaarea;

（4）HowtoimprovetheeffectivenessofcorrectingionosphericdelaysforWAAS’susersunderadverseconditions.

（5）HowtoestablishthebasictheoryandthecorrespondingframeworkofmonitoringthestochasticionosphericdisturbanceusingGPS

（6）Howtoimprovethemodellingabilityofionosphericdelayaccordingtoitsdiurnal,seasonal,annualvariationsbasedonGPS;

（7）Howtomeetthedemandofcorrectingtheionosphericdelayof high-precisionorbitdeterminationforlow-earthsatelliteusingasinglefrequencyGPSreceiver

1 Extracting（local）ionosphericinformationfromGPSdatawithhigh-precision

ThefactorsaresystematicallydescribedandanalyzedwhichlimittheprecisionofusingGPSdatatoextractionosphericdelays.TheprecisionofdeterminingionosphericdelayusingGPSisimprovedbasedonthefurtherresearchoftherelatedmodelsandmethods.Themainachievementsofthisworkincludethesomeaspectsasfollows:

（1）Basedonasimplemodelwithconstantnumberofparameters,whichconsistsofasetoftrigonometricseriesfunctions,ageneralizedionosphericmodelisconstructedwhoseparameterscanbeadjusted.Duetothepropertyofselectingthedifferentparametersaccordingtothechangelawofionosphericdelay,thenewmodelhasbetteravailabilityinthefieldoftherelatedtheoreticresearchandengineeringapplication.Theexperimentalresultsshowthatthemodelcanindicatethecharacteristicofionosphericactions,improvesfurtherthemodelingabilityoflocalionosphereandmaybeusedtocorrectefficientlyionosphericdelayofthesinglefrequencyGPSusesservicedbyDGPS.

（2）Differentcalculatingschemesaredesignedwhichareusedtoanalyzeindetailthecharacteristicsoftheeffectfrominstrumentalbias（IB）inGPSobservationsondeterminingionosphericdelays.IBisdifferentfrom noiseinGPSobservations.TheexperimentalresultsshowthattheeffectofIBismuchlargerthanthatofthenoiseonestimatingionospheicdelay,and IBcancauseionosphericdelaymeasurementstoincludesystematicerrorsoftheorderofseveralmeters.Therefore,onemustsignificantlytakenoticeofIBandremoveitsnegativeeffect,andshouldnotcasuallyconsiderIBaspartofnoisewheneverGPSdataareusedtofitionosphericmodelortodirectlycalculateionosphericdelay.

（3）StabilityofIBisstudiedwitharefinedmethodforseparatingitfromionosphericdelayusingmulti-dayGPSphase-smoothedcodedata.Theexperimentalresultsshowthat,byusingaveragingof noisewithphase-smoothedcodeobservation，theeffectofnoiseonseparatingIBfromIONcanbeefficientlyreduced,and satellitebiasplusreceiverbiasarerelativelystableandmaybeusedtopredicttheIBsofthenextsessionoreventhatofthenextseveraldays.

（4）AnewalgorithmaboutstaticrealtimedeterminationofionosphericdelayispresentedonthebasisofthepredictedvaluesofIBandthetechniqueofrealtimeaveragingofnoiseandweighted-adjustmentofdualP-codeandcarrierphasemeasurements.Thepreliminaryresultsshowthatthenewmethod,whichisbypost-processingphase-smoothedcodedatatocalculatetheIBandthenwiththemtopredictandtocorrecttheIBofdataneededtoremoveitseffects inrealtimeinthenextobservationperiods,hasrelativelybetteraccuracyandeffectivenessinestimatingionosphericdelay. Itisveryobviousthattheschemecanrelativelydecreasethenumberofunknownparameters,canefficientlyreducethemainnegativeeffectfrominstrumentalbias,andcanbeeasilyusedtodirectlyandpreciselydetermineionosphericdelaywithdual-frequencyGPSdata.Hence,themethodmaybeconsideredasanavailableschemetodetermineionosphericdelaysforWAASandmanyotherlargerangeGPSapplicationsystems.

2 Amethodofconstructinglargerange（regionalandglobal）high-precisiongridionosphericmodel─—theDifferentAreaforDifferentStations（DADS）anditsapplicationinChina

Basedonthesystematicandfurtherresearchoftheprincipleandmethodsofestablishinggridionosphericmodel（GIM）,anewmethodofestablishingaGIM-----DifferentAreasforDifferentStations（DADS）isinvestigatedwhichisadvantageousforconsideringthelocalcharactersofionosphere,avoidingtheeffectsofthegeometricalconstructionofGPSreferencenetworkonestimatingtheexternalprecisionoftheGIM,andimprovingtheprecisionofcalculatingmodelparameters.TheaboveresultsareusedtomakeapreliminaryestimationofthelatentprecisionthatcanbeobtainedbyestablishingalargerangehighprecisiongridionosphericmodelbasedontheChinesecrustmovementobservationnetwork,andtoinvestigatethepossibilitythattheGIMprovideshigh-precisionionosphericcorrection,andtoidentifytherelevantproblemswhichneedtobesolvedfortheplannedGPSWideareaAugmentationSystem（WAAS）ofChina.

3AmethodofefficientlycorrectingionosphericdelaysforWAAS’susersundertypicaladverseconditions——theAbsolutePlusRelativeScheme（APR-I）

ThecommonlyusedWAAS’sDIDCreceivedbysinglefrequencyGPSreceiverscanusuallyprovidetheeffectivecorrectionof theionosphericdelaysfortheusersundernormalconditionsandinthefieldsofcalmionosphere.However,theionosphericdelayscannotbeefficientlyaccountedforduringthoseperiodswhentheWAAScannotbroadcasttheDIDCvaluestousers,orwhenthereceiverscannotreceivetheDIDCsforwhateverreason.Theionosphericdelaycorrectionswillbelesswellknownincaseswhenthevariationsoftheionosphericdelaysmaybeverylargeduetoionosphericdisturbances.TheabovedifficultiescannotbeavoidedtobeencounteredandmustbesolvedfortheWAAS.

Forthis,anewionosphericdelaycorrectionschemeforsinglefrequencyGPSdata—theAPR-Ischemeisproposedwhichcanefficientlyaddresstheaboveproblems.

1）     ThetheoreticbasisofconstructingtheAPR-IScheme

TheWAAScanprovidehigh-precisionabsoluteionosphericdelayestimateswhenitoperatesproperly.Meanwhile,asinglefrequencyGPSreceiverservicedbytheWAAScanefficientlydeterminetherelativevariationoftheionosphericdelaysbetweentwoarbitraryepochsevenunderadverseconditionsifwithoutconsideringobservationnoises.

2）     OntheAPR-IScheme

Basedonarobustrecurrenceprocedureandanefficientcombinationapproachbetweenabsoluteionosphericdelaysandionosphericrelativechanges,theAPR-Ischeme ispresentwhichisannewmethodofcorrectingionosphericdelayforsinglefrequencyGPSuser.TheformulaofestimatingtheprecisionoftheAPR-Ischemeisgiven.AnimplementationapproachoftheAPR-Ischemeisanalyzedaswell.

TheexperimentalresultsdiscussedaboveshowthattheAPR-IschemenotonlyretainsthecharacteristicofhighaccuracyoftheDIDCfromtheWAASundernormalionosphericandreceptionconditions,butalsohasrelativelybettercorrectioneffectivenessunderdifferentabnormalconditions.TheimplementationofthismethodneednotchangethepresentbasicionosphericdelaycorrectionalgorithmoftheWAAS.Inaddition,theAPR-Imethoddoesnotimposenewdemandsonreceiverhardware,andonlyrequiresafewimprovementstoreceiversoftware.HenceitcanbeeasilyusedbysinglefrequencyGPSusers.

4Anewtheoryofmonitoringtherandomsignal—Auto-CovarianceEstimationofVariableSamples（ACEVS）anditsapplicationinusingGPStomonitortherandomionosphere

Anewapproachformonitoringionosphericdelaysisfoundanddeveloped,basedonthecharacteristicoftimeseriesobservationofGPS,aninvestigationofthestatisticalpropertiesoftheestimatedauto-covarianceoftherandomionosphericdelaywhenchangingthenumberofsamplesinthetimeseries,thedevelopmentoftherelatedbasictheoryandthecorrespondingframeworkscheme,andthefurtherresearchofusingGPSandtheaboveresearchresultstostudyionosphere.

Theconcreteworkisasfollows:

1）StudiedtheAuto-CovarianceEstimationofVariableSamples（ACEVS）

Fromageneralmathematicalaspect,thebasicmodelofACEVSisestablished.ThetheoreticandapproximatesolutionformulasforACEVSarederivedbasedontheimprovementoftheoryofwhitenoiseandthenatestrawofthestateofarandomsignalisestablishedbasedonACEVS;

2）VerifiedandmodeledthepossibilityofusingACEVStotestthechang