仪表与量测ppt课件_2

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1、Chapter6ToolsandMethodsofSignalAnalysisI.KollarBasicSignalProcessingMethodsTimeRecordsMeanValueMeanSquareValueandVarianceCorrelationFunctionProbabilityFunctionsSpectraLinearSystemsIntroductionMeasurement-toextractthemaximumamountofinformtionefficientlyandeffectively.Signalanalysisneedbedonedur

2、ingthewholemeasurementtime.Intelligentmicroprocessorprovidessophisticatedsignalprocessingcapability.Profoundunderstandingofthemeasuredresultsisvitalforwhomintendtousethem.Thischapteristoprovidethebasicsofsignalanalysisforthosewhousecomplexinstruments.ThemostimportantsignalprocessingtechniquesaT

3、hebuildingblocksandmainfeaturesoftheinstruments.Theerrorsonrandomsignalandsincewavesarediscussed.BasicSignalProcessingMethodsTherearemanyDSPtechniques.Wewillfocusontheonesthatarealreadycustomarilybuiltintoinstruments.ThepurposeistheanalysisanddesignofDSPproceduresandinstrumentsettings.Studyther

4、elationamongrecordlength,signalbandwidth,andvariancereduction.Signalofinterests:stochasticsignalswithcontinuousspectrum,sinusoidalsignalswithfixedorrandomphases,transientsignalsMeasureiterationstoadaptmodeltoreduceerrors.Approximationisnecessarytoanalyzeerrors,e.g.equivalentbandlimitedwhitenois

5、e(Bendat1971)SignalProcessing-EquivalentBandlimitedWhiteNoiseAutocovariancefunctionCovariancePowerSpectralDensityfunctionFrequencyDomainSubstitutionFrequencyDomainAdvantages:Timedomainconvolution=>frequencydomainmultiplicationSignalandnoisecanbedecomposedintodifferentbandsforveryhighnoisereject

6、ion.Periodwavesarediscreteintimedomain.Attainabledynamicrange(80-100dB)ismuchlarger.Slightnonlinearitiescanbeeasilydetected(harmonics).FFTisaverypowerfultool,hence,correlationismuchfasterviafrequencydomainthendirectlyintimedomain.TimeDomainAdvantages:It’sanaturaltoviewtimedomainsignal.Recursive

7、methodsprovideon-linecalculation.Timevaryingsystemscanbemodeledeasily.TimedomainmethodsarenotsensitivetosignaltypeswhileFdomainhasleakagefornonperiodicsignals.Certainnonlinearityareeasilyrecognized(slipping,slewrate).DSP-Time/Freq