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UWBCHIRP信号的多径时延频域提取方法.docx

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UWBCHIRP信号的多径时延频域提取方法 Introduction UWB(Ultra-Wideband)technologyiswidelyusedinvariousapplications,suchasradar,communication,andpositioning,duetoitsadvantagesinhighdatarate,low-powerconsumption,andaccuratedistancemeasurement.However,thepropagationofUWBsignalsisaffectedbymultipathfading,whichleadstoadegradedsignalqualityandreducedpositioningaccuracy.Therefore,theaccurateextractionofmultipathinformationiscriticalforUWB-basedsystems.Inthispaper,weproposeafrequency-domainmethodforextractingmultipathdelayinformationfromUWBCHIRPsignals. UWBCHIRPSignals UWBCHIRPsignalsaretransmittedbysweepingthroughawidefrequencyrangeinashorttime,anditsfrequencycomponentsareconcentratedinanarrowbandwidth,whichmakesitresistanttointerferenceandallowsforahigh-resolutiondelayestimation.ThereceivedUWBCHIRPsignalcanberepresentedas: where,A(t)istheamplitudeofthetransmittedsignal,Tistheperiodofthesignal,f(t)isthefrequencymodulationfunction,andn(t)isthenoise.Thefrequencymodulationfunctionf(t)isalinearchirpsignalwithaconstantsweeprate,whichcanbeexpressedas: Wheref0isthecenterfrequencyofthechirpsignal,αisthefrequencymodulationrate,andτisthestartingtimeofthechirpsignal. MultipathPropagationModel ThemultipathpropagationmodelofUWBCHIRPsignalsisasumofdelayedandattenuatedversionsoftheoriginalsignal.Itcanbeexpressedas: Wheretiisthedelaytimeoftheithpath,hiisthecomplexchannelgain,andMisthetotalnumberofpropagationpaths.Assumethatthedelaytimesandchannelgainsofeachpathareknown,thereceivedsignalinthefrequencydomaincanberepresentedas: WhereH(f)isthefrequencyresponseofthechannel,andF(f)istheFouriertransformofthetransmittedsignal. Frequency-DomainMethodforMultipathDelayExtraction Theproposedmethodisafrequency-domainapproachthatestimatesthedelaytimesofeachmultipathcomponentbyanalyzingthespectrumofthereceivedsignal.Thestepsoftheproposedmethodcanbesummarizedas: Step1:Acquisitionofthereceivedsignal ThereceivedUWBCHIRPsignalissampledandstoredinthetimedomain. Step2:Frequency-domaintransformation TheFouriertransformisappli