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Lesson14SpectrumAnalyzers《电子技术专业英语教程》冯新宇主编电子工业出版社《电子技术专业英语教程》2Lesson14SpectrumAnalyzers•Backgrounds•Texttour•Languageinuse–Vocabulary–Structure–Reading/writingtechniques2020/1/30《电子技术专业英语教程》3•Terminology–FCC•FederalCommunicationsCommission联邦通信委员会–radiofrequency•射频–spectrumanalysis•频谱分析–hertz•n.【电】赫，赫兹(频率单位，周/秒简作Hz.)–predetection•预检波；检波前的Backgrounds2020/1/30《电子技术专业英语教程》4•Terminology–mixer•混频器–R&D•=ResearchandDevelopment研究与开发–CATV•=CommunityAntennaTV(system)共用天线电视(系统)；【计】电缆电视，有线电视–TRF•=TunedRadioFrequency调谐射频Backgrounds2020/1/30《电子技术专业英语教程》5Texttour•Outline–WhatisaSpectrumAnalyzer?–TheapplicationsandfunctionofSpectrumAnalyzer–Manyforcesareimpactingtheusesandneedsforsignalanalyzers–Timeversusfrequencydomain–BasicSpectrumAnalyzerOperation–SweptSuperheterodyneSpectrumAnalyzer•Filterbankreal-timeanalyzers•FastFourierTransformanalyzers2020/1/30《电子技术专业英语教程》6WhatisaSpectrumAnalyzer?•Spectrumanalysisisaquickmethodtoobserveandmeasuresignallevelsandsignaldistortions.•ThedisplaygivestheuseravisualrepresentationofthemagnitudeoftheFouriertransformoftheinputsignals.aSpectrumAnalyzer2020/1/30《电子技术专业英语教程》7TheapplicationsandfunctionofSpectrumAnalyzer•Spectrumanalysisisessentiallytheexaminationofamplitudevs.frequencyofagivensignalsource,antenna,orsignaldistributionsystem.•Thisanalysiscanyieldimportantinformationaboutthesignalssuchasstability,distortion,amplitude,andtypesandqualityofmodulation.•ThemodernspectrumanalyzerhasfoundmanycomplexusesrangingfromtheR&Dlabtomanufacturingandfieldservice.–Thesignalanalyzerhasbeenalaboratoryinstrumentofgreatvalue.ThequickabilitytoviewwidespectrumwidthsandthenquicklyzoomintocloselyexaminesignalsofinteresthasbeenhighlyvaluedbytheR&Dengineer.–Inthemanufacturingarea,thespeedofmeasurementscombinedwiththeabilitytoaccessthesedatathroughcomputershasallowedverycomplexmeasurementstobemadequickly,accurately,andrepeatable.2020/1/30《电子技术专业英语教程》8Manyforcesareimpactingtheusesandneedsforsignalanalyzers(1)•Thegreatproliferationofhigh-speeddigitalcomputershascreatedtheneedforwidefrequencyrangediagnosticinstruments.–ThesetoolsallowthedesignerstoscanquicklyforpossibleproblemsthatmayviolateregulatoryrequirementssuchasthosefromtheFederalCommunicationsCommission(FCC).•Therapidriseinradio-frequencytelecommunicationshasgivenrisetoevenmoretestingtoverifyregulatoryrequirementsfortransmissionmodes.–Currentrequirementsarestrictformobileradiotelephones.Theseincludemeasurementsofspectrumoccupancy,powerlevels,timedomainresponses,andotherspuriousemissions.Cabletelevisionandbroadcastvideoservicesalsoprovideopportunitiesforthesignalanalyzertobeused,modulationbandwidth,signaltonoise,carrierlevel,andharmonicsareexamples.2020/1/30《电子技术专业英语教程》9Manyforcesareimpactingtheusesandneedsforsignalanalyzers(2)•Theworldofradiofrequency(RF)ormicrowavefrequencyuseisconstantlyplacingincreasingdemandsuponboththeenduseequipmentandthetestequipment.–Justasequipmentneedsforeachoftheendusersvary,sodotherequirementsfortheassociatedsignalanalyzersvary.Thusacompleteunderstandingoftheintendedapplicationisneededbeforeitispossibletoselectanappropriatespectrumanalyzer.Asthemeasurementneedsofaspecifictypebecomemoreintense,findingasignalanalyzerspecificallytailoredtothatapplicationmaybepossible.–Assignalanalyzershavebeendesignedforuseinspecificapplicationareas,theydonotsimplydisplayrawfrequencyandamplitudemeasurementsbuttranslatethosemeasurementsintomorecompletesolutions.–Spectrumanalyzersmaynowbeobtainedtoassistthedigitaldesignerindiagnosingandimprovingtheradio-frequencyinterference(RFI)performanceoftheirhigh-speeddigitalsystems.–Theseanalyzers“speak”thelanguageoftheapplicationandaremoreeasilyoperatedandunderstoodbyelectromagneticinterferenceengineers.–Therearesimilarexamplesformanyotherareas,suchasrfmobiletelecommunicationsandtheCATVorbroadcastvideomarketplaces.2020/1/30《电子技术专业英语教程》10Timeversusfrequencydomain•Theusefulnessofthistoolmaybebestshowninacomparisonoftimedomainandfrequencydomainanalysisofasimplesignal.Thetimedomainoscilloscopeprovidesadisplayofamplitudevs.time(Figure14-1(a)).Theverticalaxisofthisdisplayisrepresentativeoftheamplitudeofthesignal,whilethehorizontalaxisisthatoftime,increasingfromlefttoright.Inthespectrumanalyzer,theinstrumentprovidesadisplayofamplitudeversusfrequency(Figure14-1(b)).Theverticalaxisofthisdisplayisalsorepresentativeoftheamplitudeofthesignal,whilethehorizontalaxisisfrequency,increasingfromlefttoright.Figure14-1(c)depictstherelationshipsoftheseanalysistechniques.Thespectrumanalyzerresolvesthespectralmakeupofthesignalanddisplaysitinawideamplitudeandfrequencyrange.Figure14-1Therelationshipbetweentimedomainandfrequencydomainanalysis2020/1/30《电子技术专业英语教程》11BasicSpectrumAnalyzerOperation•Theseparationofthefrequencycomponentsofsignalsmaybeattainedinseveralways.Themostbasicformofspectrumanalysis,calledtunedrf(TRF)analysis,issimplyaccomplishedthroughtheuseoftunablefilterswherethecenterfrequencyofthefilterisadjustableandisfollowedbybroadbanddetectors.•TheseTRFanalyzersaresomewhatdi