卫星导航在海上运输领域的应用

APPLICATIONSOFSATELLITENAVIGATIONINSEATRANSPORTATIONANDPROTECTIONOFOCEANRESOURCEANDNTIRONMENT2002.12InGlobalSatelliteNavigationSystems(GNSS)generallyareGPS,GLONASSandGALILEO.IfallthesystemsareinuseitisreallythetimesofSatelliteNavigationandthereliabilityofsatellitenavigationwillbe100%.Aswellknown，oceanis70%oftheEarth,itwillbeemphasizedinthiscentury，becausemoreandmoreactivitiesofhumanbeingswillbeatseawiththedevelopmentofscienceandtechnology.Theactivitiesatseawillgreatlydependentonsatellitenavigation.Sosatellitenavigationatseawillbeanimportantapplicationarea.Sinceearly1990'sGPShasbeenthemostimportantsysteminGNSS.TheGPSindustryismainlyindevelopedcountry.AccordingtotheInteragencyGPSExecutiveBoard(IGEB)ofUS,theworldwidemarketsofGPSgoods&serviceswillreach$16Bby2003.ThemarketsshareisthatUS30%,Europe23%,Japan44%,Asia2%andothers1%.The2%marketshareofAsiapointsthattheGPSindustryhasnotbeenformedyetinChina.ItalsocanbesaidthatthereisalargedevelopmentspaceinChinaforGPSindustry.Onotherhand,thesatellitenavigationindustryisveryimportantforChinamodernization.Chinaisalargecountryinseaandrivertransportationwithlongcoastlineandrivertransportationroutes.Sotherearewideapplicationareasinefficientmanagementofseatransportation,developmentandprotectionofoceanresources,andprotectionofoceanentironment.HerewewillgivesomepresentationsaboutGNSSapplicationsatsea.1.TheapplicationsofGNSSatseatransportationareaSeatransportationareagenerallyincludesshippingsystems,trafficmanagementsystems,andmaritimenavigationsystems.Nowtakesomesystemsforexamples:MaritimeDGPSserviceforenhancedaccuracyandsafety,thatisGPSLocalaugmentsystem.GPS-basedvesseltrackingandtrafficmanagementmaximizeseffectivenessofwaterways,suchasVTSandAISsystems.Measurementandmanagementofmaritimenavigationsystemswithhigherprecisioninharborandcoastline,sothatimprovedsafetyincreasesmaritimecommerce.Package/cargodeliverytrackingandmanagementinmodernlogisticssystems.Recreationalfacilitiesatsea.Andsoon.Nextwewilldescribetheapplicationsystemswhichhavebeenandisdevelopingandwillbeusefulforseatransportation：1.1ToestablishNationalDGPS-NDGPSforseaandlandtrafficusageInChinatherehasbeenGPSLocalaugmentsystem-RBN/DGPSalongcoastline,supportedbyChinaCommunicationministry.AccordingtothedevelopmentofGNSS,itisnecessarytoexpandRBN/DGPStoalloverthecountryasNationalDGPS,atthesametodevelopRBN/D-GALILEO.IntheUS,theremainlyaretwoGPSaugmentsystems,oneisRBN/DGPSsupportedbyUSCG,andanotherisWAASsupportedbyUSFAA.USCGbelongstoUSDOT,especiallyforthemanagementofmaritimenavigationsystems.USCGhasmadegreatachievementsinthedevelopmentsofGPSapplications.Earlyinthe1983,theRBN/DGPSsystemwasstartedtoresearch.AndnowRBN/DGPShasbethemainGPSLocalAugmentsystemavailablein34countries.Since1997theUSDOThasorganizedagrouptoresearchthesystemwhichwillprovidetheDGPSserviceinnationalwide.Atlast,thegroupapprovedthattoexpandtheUSCGRBN/DGPSasNationalDGPSisthemostefficientandeconomicproject。SotheUSDOThasdeterminedtoexpandRBN/DGPSasNationalDGPS--NDGPS，toprovidedifferentialservicealloverthecountry.InChina，from1997to1999,thereare20RBN/DGPSreferencestationsestablishedandbroughtintooperationinsuccession,supportedbyChinaCommunicationMinistry.TheRBN/DGPScanprovideservicewithmeterorsub-meterpositioningprecision.BasedonthesesystemswecantaketheUSDOTasreferencetoexpandtheRBN/DGPStobeasNationalDGPS,andatthesametimetoestablishGAOLILEOLocalsystem.TheNationalDGPSwillprovidedifferentialserviceforharbor,coast,rivertrafficandlandtrafficwithhigherprecision.ComparingwithFAAWAAS,whytheUSDOTselectedtoexpandRBN/DGPSasNationalDGPS?AccordingtotheanalysisofUSION(theinstituteofnavigation),WAASisnotoptimizedforsurface(maritimeandterrestrial)use,rather,itwasdesignedprimarilyforaviation.ThecurrentWAAStestsignalsaretransmittedbytwogeo-stationarysatellitesonaline-of-sight,L-bandradiofrequency.Thismeansthatifanythingobstructstheviewoftheportionoftheskywherethesatelliteis,theWAASsignalwillbeblocked.Sincegeo-stationarysatellitesarepositionedovertheequator,thefarthernorthusersare,thegreaterthelikelihoodoftheobstruction.Incontrast,themediumfrequency(285-325kHz)radiobeacon-basedMaritimeDGPSServiceisoptimizedforsurface(maritimeandterrestrial)applicationbecauseit'sgroundwavesignalshugtheearthandwraparoundobjects.SoinordertodevelopNationalDGPS,toexpandRBN/DGPSisthemostsuitableforsurfaceusers.1．2TheapplicationsofcompatiblereceiverofGPSandGALILEOinVTSandAISInSOLASchapter5,adoptedbyIMOinDec.2000,itisdescribedthat300TGormoreinternationalservicecargoships,500TGormoredomesticservicecargoshipsandallpassengershipsmustbeequippedwithAISfromJuly1st2002,andthedeadlineisJuly1st2008.GPSreceiveristheimportantcomponentinAIStransceiver.InordertogetimprovedsafetyandnavigationreliabilityitisnecessarytousecompatiblepositioningcomponentwithGPSandGALILEOinAIS.InChinathereareabout300thousandsshipsinseveralshippinggroups,whichmayequippedAIStransceiver.ChinaCommunicationMinistryhasmadeplantoestablishtheAISsystemalongthecoastline.TheoperationofAISnetwillpromotetheapplicationofGNSS.Expectofl