电子科技大学DSP半期考试题目总结PPT课件

精品课件,1,第一类题：序列周期的确定,Arethefollowingsequencesperiodic?Iftheanswerispositive,determinethefundamentalperiodforeachsequence.a)b)c),精品课件,2,第二类题：系统性质的确定,Foreachofthefollowingdiscrete-timesystems,whereynandxnare,respectively,theoutputandtheinputsequences,determinewhetherornoteachsystemis(1)linear,(2)causal,(3)stable,(4)shift-invariant:,精品课件,3,第三类题：DTFT，DFT计算,1.Letxn=n+n-1,a)DeterminetheDTFTofxn.b)Determineandsketchthemagnitudeandphasespectrumofxn.c)Calculatethe4-pointDFTofxn.,2.GivetheDTFTofthefollowingsequences:x1n=3(1/3)n,|n|3;x2n=annn-N;,精品课件,4,第四类题：DTFT、DFT的性质,1.A498-pointDFTXkofarealsequencexnhasthefollowingsamples:X0=2,X11=7+j3,Xk1=-2-j,X112=3-j0.7,Xk2=-4+j,X249=3,X309=-4-j2,X386=3+j0.7,X412=-2+j,andX487=7-j3.ThevaluesofremainingDFTsamplesareassumedtobezero.a)Determinethevaluesoftheindicesk1andk2.b)Determinethevaluesofand.c)Determineandx249.d)Determinetheenergyofxn.,精品课件,5,2.Asequencexnoflength8hastheeight-pointDFTXkshowninFig.Anewsequenceoflength16isdefinedby:LetYkbethe16-pointDFTofyn.PleasechoosethesketchofYkfrominthenextpage,andproveyourresult.,精品课件,6,Solution:AccordingtothedefinitionofDFT,whenk=0,1,7,Yk=Xk;whenk=8,9,15,Yk=Xk-8.OrYk=X8.,精品课件,7,第五类题：圆周卷积和线性卷积,Forthefollowingtwosequences:,Let(linearconvolution),4(circleconvolution),sketchy1n,y2n.,精品课件,8,第六类题：系统响应计算,Ifadiscrete-timeLTIsystemsinputisTheoutputisTrytofindouttheimpulseresponseandfrequencyresponseofthesystem，andgiveitsinput-outputrelation(differenceequation).,精品课件,9,第七类题：信号采样,Ablockdiagramofdiscretetimeprocessingsystemisshownasfig1.TheFToftheinputsignalxC(t)isshownasfig2,with0=2(1000)rad/s.TheDiscretetimesystemisaideallowpassfilterwithfrequencyresponse:(1)Fornoaliasinghappenswhentheinputsignalissampled,whatistheminimumsamplingrateFs=1/T?Andsketchthefrequencyspectrumof