《李贵阳外文翻译》word版

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1、IIRDigitalFilterDesignAnimportantstepinthedevelopmentofadigitalfilteristhedeterminationofarealizabletransferfunctionG(z)approximatingthegivenfrequencyresponsespecifications.IfanIIRfilterisdesired,itisalsonecessarytoensurethatG(z)isstable.Theprocessofderivingthetransferfun

2、ctionG(z)iscalleddigitalfilterdesign.AfterG(z)hasbeenobtained,thenextstepistorealizeitintheformofasuitablefilterstructure.Inchapter8,weoutlinedavarietyofbasicstructuresfortherealizationofFIRandIIRtransferfunctions.Inthischapter,weconsidertheIIRdigitalfilterdesignproblem.T

3、hedesignofFIRdigitalfiltersistreatedinchapter10.Firstwereviewsomeoftheissuesassociatedwiththefilterdesignproblem.AwidelyusedapproachtoIIRfilterdesignbasedontheconversionofaprototypeanalogtransferfunctiontoadigitaltransferfunctionisdiscussednext.Typicaldesignexamplesareinc

4、ludedtoillustratethisapproach.WethenconsiderthetransformationofonetypeofIIRfiltertransferfunctionintoanothertype,whichisachievedbyreplacingthecomplexvariablezbyafunctionofz.Fourcommonlyusedtransformationsaresummarized.Finallyweconsiderthecomputer-aideddesignofIIRdigitalfi

5、lter.Tothisend,werestrictourdiscussiontotheuseofmatlabindeterminingthetransferfunctions.9.1preliminaryconsiderationsTherearetwomajorissuesthatneedtobeansweredbeforeonecandevelopthedigitaltransferfunctionG(z).Thefirstandforemostissueisthedevelopmentofareasonablefilterfrequ

6、encyresponsespecificationfromtherequirementsoftheoverallsysteminwhichthedigitalfilteristobeemployed.ThesecondissueistodeterminewhetheranFIRorIIRdigitalfilteristobedesigned.Inthesection,weexaminethesetwoissuesfirst.NextwereviewthebasicanalyticalapproachtothedesignofIIRdigi

7、talfiltersandthenconsiderthedeterminationofthefilterorderthatmeetstheprescribedspecifications.Wealsodiscussappropriatescalingofthetransferfunction.9.1.1DigitalFilterSpecificationsAsinthecaseoftheanalogfilter,eitherthemagnitudeand/orthephase(delay)responseisspecifiedforthe

8、designofadigitalfilterformostapplications.Insomesituations,theunitsampleresponseorstepresponsema