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GPS与Galileo共用的MBOC信号研究.docx

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GPS与Galileo共用的MBOC信号研究 1.Introduction GlobalPositioningSystem(GPS)andGalileoaretwooftheleadingsatellitenavigationsystemsintheworld.Bothsystemsplayacriticalroleinvariousapplications,includingtransportation,military,aviation,andpersonalnavigation.GPSandGalileousedifferentsignals,withGPSusingL1,L2andL5frequencies,andGalileousingE1,E5a,E5b,andE6frequencies.However,bothsystemsnowalsouseacommonsignalmodulation,theMultiplexedBinaryOffsetCarrier(MBOC)waveform.ThispaperaimstoexplorethebenefitsandlimitationsoftheMBOCwaveformanditsimplicationsforGPSandGalileocoexistence. 2.MBOCSignal TheMBOCwaveformrepresentsamodificationoftheexistingBinaryOffsetCarrier(BOC)signalusedbyGPSsinceitsinception.InBOC,twocarriersareshiftedinphasebyaspecificamount,withonecarrierbeingtwicethefrequencyoftheother.Thiscreatesasignalwithawiderbandwidth,providingbetteraccuracyinpositionfixes.However,BOCsignalshaveahighersidelobelevel,whichcancauseinterferencewithneighboringfrequencies. Toovercomethislimitation,MBOCmodulatesBOCwithasecondarycode,resultingintwodifferenttypesofchips.TheprimarychipisastandardBOCsignal,whilethesecondarychipaddsapulsetotheBOCsignal'sedges,resultinginanasymmetricwaveform.Thisallowsforbettersignaltrackingandreducesinter-modulationbetweensignals. MBOCmodulationwasintroducedtoGalileoin2003andtoGPSin2007.Thesignalspecificationwasagreeduponbythetwosystemstofacilitatecoexistenceandinteroperability. 3.BenefitsofMBOCforGPSandGalileo TheuseofacommonsignalmodulationforGPSandGalileoprovidesseveralbenefits.Firstly,itensuresthatbothsystemscanoperateinthesamefrequencybandwithoutinterference.Secondly,itfacilitatessignalinteroperability,whichisbeneficialforequipmentmanufacturers,whocanproducereceiversthatcanreceivebothGPSandGalileosignals.Thirdly,theuseofMBOCimprovessignaltrackinginmultipathandurbancanyonenvironments,whichcanenhanceaccuracyandavailabilityofpositioninginformation. 4.LimitationsofMBOCforGPSandGalileo However,theuseofMBOCmodulationdoescomewithsomelimitations.Onesignificantlimitatio