滤波器英文.docx

滤波器英文.docx

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滤波器英文

Thesimulationandtherealizationofthedigitalfilter

Withtheinformationageandtheadventofthedigitalworld,digitalsignalprocessinghasbecomeoneoftoday'smostimportantdisciplinesanddoortechnology.Digitalsignalprocessingincommunications,voice,images,automaticcontrol,radar,military,aerospace,medicalandhouseholdappliances,andmanyotherfieldswidelyapplied.Inthedigitalsignalprocessingapplications,thedigitalfilterisimportantandhasbeenwidelyapplied.

1、figuresUniton:

Analoganddigitalfilters

Insignalprocessing,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:

A

（f）A

（f）

11

0f

f0f

f

（a）（b）

A

（f）A

（f）

11

0f

f

f0f

f

f

（c）（d）

（a）LPF（b）HPF（c）BPF（d）BSF

2、MATLABintroduced

MATLABisamatrixlaboratory（MatrixLaboratory）isintended.Inadditiontoanexcellentvaluecalculationcapability,italsoprovidesprofessionalsymbolsterms,wordprocessing,visualizationmodeling,simulationandreal-timecontrolfunctions.MATLABastheworld'stopmathematicalsoftwareapplications,withastrongengineeringcomputing,algorithmsresearch,engineeringdrawings,applicationsdevelopment,dataanalysisanddynamicsimulation,andotherfunctions,inaerospace,mechanicalmanufacturingandconstructionfieldsplayinganincreasinglyimportantrole.AndtheClanguagefunctionrich,theuseofflexibility,high-efficiencygoalsprocedures.Highlanguagebothadvantagesaswellaslowlevellanguagefeatures.Therefore,Clanguageisthemostwidelyusedprogramminglanguage.AlthoughMATLABisacomplete,fullyfunctionalprogrammingenvironment,butinsomecases,dataandprocedureswiththeexternalenvironmentoftheworldisverynecessaryanduseful.FilterdesignusingMatlab,couldbeadjustedwiththedesignrequirementsandfiltercharacteristicsoftheparameters,visualsimple,greatlyreducingtheworkloadforthefilterdesignoptimization.

Intheelectricitysystemprotectionandsecondarycomputercontrol,manysignalprocessingandanalysisarebasedonarecertaintypesYeroskipouandthesecondharmonicsofthesystemvoltageandcurrentsignals（especiallyatDprocess）,aremixedwithavarietyofcomplexcomponents,thefilterhasbeeninstalledpowersystemduringthecriticalcomponents.Currentcomputerprotectionandtheintroductionoftwodigitalsignalprocessingsoftwaremainfilter.Digitalfilterdesignusingtraditionalcumbersomeformula,theneedtochangetheparametersafterrecalculation,especiallyinhighfilters,filterdesignworkload.UsesMATLABsignalprocessingboxescanachieverapidandeffectivedigitalfilterdesignandsimulation.

MATLABisthebasicunitofdatamatrix,withitsdirectivesBiaodashimathematics,engineering,commonlyusedformisverysimilar,itisusedtosolveaproblemthaninMATLABC,FortranandotherlanguagesEndprecisionmuchthesamething.ThepopularMATLAB5.3/Simulink3.0includinghundredsofinternalfunctionwiththemainpackand30typesoftoolkits（Toolbox）.kitscanbedividedintofunctionaltoolkitsanddisciplinestoolkit.MATLABtoolkitusedtoexpandthefunctionalsymbolsterms,visualizationsimulationmodelling,wordprocessingandreal-timecontrolfunctions.professionaldisciplinestoolkitisastrongertoolkits,toolkitscontrol,signalprocessingtoolkit,toolkits,etc.belongingtosuchcommunications

MATLABuserstoopenwidelywelcomed.Inadditiontotheinternalfunction,allthepackagesMATLABtoolkitsarereadabledocumentandthedocumentcouldbeamended,modifiedorusersthroughYuanchengxutheconstructionofnewprocedurestopreparethemselvesforkits.

3、Digitalfilterdesign

Digitalfilterdesignofthebasicrequirements

Digitalfilterdesignmustgothroughthreesteps:

（1）Identificationofindicators:

Inthedesignofafilter,theremustbesomeindicators.Theseindicatorsshouldbedeterminedonthebasisoftheapplication.Inmanypracticalapplications,digitalfiltersareoftenusedtoachievethefrequencyoperation.Therefore,indicatorsintheformofgeneraljurisdictiongivenfrequencyrangeandphaseresponse.Marginskeyindicatorsgivenintwoways.Thefirstisabsoluteindicators.ItprovidesafunctiontorespondtothedemandsofthegeneralapplicationofFIRfilterdesign.Thesecondindicatoristherelativeindicators.Itsvalueintheformofanswerstodecibels.Inengineeringpractice,themostpopularofsuchindicators.Forphaseresponseindicatorsforms,usuallyinthehopethatthesystemwithalinearphasefrequencybandshuman.Usinglinearphasefilterdesignwiththefollowingresponsetotheindicatorsstrengths：

①itonlycontainsafewalgorithms,nopluraloperations；②thereisdelaydistortion,onlyafixedamountofdelay;③thefilterlengthN（numberofbandsforN-1）,thevolumecalculationforN/2magnitude.

（2）Modelapproach:

Onceidentifiedindicatorscanuseapreviousstudyofthebasicprinciplesandrelationships,afiltermodeltobeclosertothetargetsystem.

（3）Achieved:

theresultsoftheabovetwofilters,usuallybydifferentialequations,systemfunctionorpulseresponsetodescribe.Accordingtothisdescriptionofhardwareorsoftwareusedtoachieveit.

4、IntroducedFPGA

Programmablelogicdeviceisagenericlogiccanuse