GNSS掩星探测大气算法及误差分析-豆柴文库

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GNSS掩星探测大气算法及误差分析
GNSS(GlobalNavigationSatelliteSystem)isasatellite-basednavigationsystemthatprovideslocationandtimeinformation.However,theGNSSsignalisaffectedbyvarioussourcesoferrors,includingatmosphericerrorsthatreducetheaccuracyofGNSSpositioning.TheGNSSoccultationtechniqueisoneofthemosteffectiveapproachestomitigateatmosphericerrorsandimprovepositioningaccuracy.Inthispaper,wewillpresenttheGNSSoccultationalgorithmanderroranalysisforatmosphericdetection.
TheGNSSoccultationtechniqueusestheradiosignalstransmittedbytheGNSSsatellitestoprobetheEarth'satmosphere.WhentheGNSSsatelliteissettingorrising,itssignalspassthroughtheatmosphereatalowangle,whichcausesatmosphericrefractionanddelaysthesignal'straveltime.TheGPSreceivermeasuresthedelayinthesignaltodeterminetherefractivityprofileoftheatmosphere.Theintensityofthesignalisalsoaffectedbytheatmosphericabsorption,scattering,anddiffraction.Byanalyzingtherefractionandabsorptioncharacteristicsofthesignal,theGNSSreceivercanestimatethetemperature,pressure,andhumidityprofilesoftheatmosphere.
TheGNSSoccultationalgorithmconsistsofseveralsteps,includingsignalacquisition,tracking,andprocessing.ThesignalacquisitionprocessinvolvessearchingfortheGNSSsatellitesignalsandmeasuringtheirphaseandfrequency.ThesignaltrackingprocessinvolvestrackingthephaseandfrequencyoftheGNSSsignalsandcompensatingfordelayscausedbyatmosphericrefractionandsatellitemotion.Thesignalprocessingprocessinvolvesanalyzingthephaseandfrequencymeasurementstoestimatetheatmosphericparameters.
TheatmosphericparametersthatcanbeestimatedfromtheGNSSoccultationtechniqueincludetemperature,pressure,andhumidity.Thetemperatureprofilecanbeestimatedfromtherefractivityindexoftheatmosphere,whichisafunctionofpressure,temperature,andhumidity.Thepressureprofilecanbederivedfromthehydrostaticequilibriumequation,whichrelatesthepressuregradienttothegravityandtemperatureprofiles.ThehumidityprofilecanbeobtainedfromthedifferentialabsorptionofGNSSsignalsatdifferentfrequencies,whichissensitivetothewaterv