搜索
英文原文ThesimulationandtherealizationofthedigitalfilterWiththeinformationageandtheadventofthedigitalworld,digitalsignalprocessinghasbecomeoneoftoday'smostimportantdisciplinesanddoortechnology.Digitalsignalprocessingincommunications,voice,images,automaticcontrol,radar,military,aerospace,medicalandhouseholdappliances,andmanyotherfieldswidelyapplied.Inthedigitalsignalprocessingapplications,thedigitalfilterisimportantandhasbeenwidelyapplied.1、figuresUniton:AnaloganddigitalfiltersInsignalprocessing,thefunctionofafilteristoremoveunwantedpartsofthesignal,suchasrandomnoise,ortoextractusefulpartsofthesignal,suchasthecomponentslyingwithinacertainfrequencyrange.Thefollowingblockdiagramillustratesthebasicidea.Therearetwomainkindsoffilter,analoganddigital.Theyarequitedifferentintheirphysicalmakeupandinhowtheywork.Ananalogfilterusesanalogelectroniccircuitsmadeupfromcomponentssuchasresistors,capacitorsandopampstoproducetherequiredfilteringeffect.Suchfiltercircuitsarewidelyusedinsuchapplicationsasnoisereduction,videosignalenhancement,graphicequalisersinhi-fisystems,andmanyotherareas.Therearewell-establishedstandardtechniquesfordesigningananalogfiltercircuitforagivenrequirement.Atallstages,thesignalbeingfilteredisanelectricalvoltageorcurrentwhichisthedirectanalogueofthephysicalquantity(e.g.asoundorvideosignalortransduceroutput)involved.Adigitalfilterusesadigitalprocessortoperformnumericalcalculationsonsampledvaluesofthesignal.Theprocessormaybeageneral-purposecomputersuchasaPC,oraspecialisedDSP(DigitalSignalProcessor)chip.TheanaloginputsignalmustfirstbesampledanddigitisedusinganADC(analogtodigitalconverter).Theresultingbinarynumbers,representingsuccessivesampledvaluesoftheinputsignal,aretransferredtotheprocessor,whichcarriesoutnumericalcalculationsonthem.Thesecalculationstypicallyinvolvemultiplyingtheinputvaluesbyconstantsandaddingtheproductstogether.Ifnecessary,theresultsofthesecalculations,whichnowrepresentsampledvaluesofthefilteredsignal,areoutputthroughaDAC(digitaltoanalogconverter)toconvertthesignalbacktoanalogform.Notethatinadigitalfilter,thesignalisrepresentedbyasequenceofnumbers,ratherthanavoltageorcurrent.Thefollowingdiagramshowsthebasicsetupofsuchasystem.Unitreferstotheinputsignalsusedtofilterhardwareorsoftware.Ifthefilterinput,outputsignalsareseparated,theyareboundtorespondtotheimpactoftheUnitisseparated,suchasdigitalfiltersfilterdefinition.Digitalfilterfunction,whichwastoimportsequencesXtransformationintoexportoperationsthroughaseriesY.Accordingtofiguresfilterfunction24-hourliveresponsecharacteristics,digitalfilterscanbedividedintotwo,namely,unlimitedlonglivelonglivethecorrespondingIIRfilterandthelimitedresponsetoFIRfilters.IIRfiltershavetheadvantageofthedigitalfilterdesigncanusesimulationresults,andsimulationfilterdesignofalargenumberoftablesmayfacilitatesimple.Itistheshortcomingsofthenonlinearphase;Linearphaseifrequired,willusetheentirenetworkphase-correction.Imageprocessingandtransmissionofdatacollectionisrequiredwithlinearphasefiltersidentity.AndFIRlinearphasedigitalfiltertoachieve,butanarbitrarymargincharacteristics.Impactfromthedigitalfilterresponseoftheunitscanbedividedintotwobroadcategories:theimpactofthelimitedresponse(FIR)filters,andunlimitednumberofshocksto(IIR)digitalfilters.FIRfilterscanbestrictlylinearphase,butbecausethesystemFIRfilterfunctionextremityfixedattheoriginalpoint,itcanonlyusethehighernumberofbandstoachievetheirhighselectivityforthesamefilterdesignindicatorsFIRfiltercalledbandthanafewhigh-IIR5-10times,thecostishigher,Signaldelayisalsolarger.Butifthesamelinearphase,IIRfiltersmustbenetwork-widecalibrationphase,thesamesectionalsoincreasethenumberoffiltersandnetworkcomplexity.FIRfilterscanbeusedtoachievenon-Diguiway,notinalimitedprecisionofashock,andintothehomesandquantitativefactorsofuncertaintyarisingfromtheimpactoferrorsthanIIRfiltersmallnumber,andFIRfiltercanbeusedFFTalgorithms,thecomputationalspeed.ButunlikeIIRfiltercanfilterthroughthesimulationresults,thereisnoready-madeformulaFIRfiltermustusecomputer-aideddesignsoftware(suchasMATLAB)tocalculate.So,abroaderapplicationofFIRfilters,andIIRfiltersarenotverystrictrequirementsonoccasions.Unitfromsub-functionscanbedividedintothefollowingfourcategories:(1)Low-filter(LPF);(2)high-filter(HPF);(3)belt-filter(BPF);(4)topreventfilter(BSF).Thefollowingchartdottedlinefortheidealsofthefilterfrequencycharacteristics:A1(f)A2(f)10c2fc2f(a)(b)A3(f)A4(f)0c1c2fc1c2f(c)(d)(a)LPF(b)HPF(c)BPF(d)BSF2、MATLABintroducedMATLABisamatrixlaboratory(MatrixLaboratory)isintended.Inadditiontoanexcellentvaluecalculationcapability,italsoprovidesprofessionalsymbolsterms,wordprocessing,visualizationmodeling,simulationandreal-timecontrolfunctions.MATLABastheworld'stopmathematicalsoftwareapplications,withastrongengineeringcomputing,algorithmsresearch,engineeringdrawings,applicationsdevelopment,dataanalysisanddynamicsimulation,andotherfunctions,inaerospace,mechanicalmanufacturingandconstructionfieldsplayinganincreasinglyimportantrole.AndtheClanguagefunctionrich,theuseofflexibility,h