信号与系统signal-and-system英文版往年考试题1

Test（Chapter1,2,3,4）参考答案I.Blankfilling(Totalscores60,eachscores5.)1、)0(1fa（70％）2、2/1（96％）3、)()(ttuet（92％）4、Piecewisefunctioncanbecomprisedbyrectangularwindowfunctions(可以用矩形窗函数构造分段函数).Considerasignal)]1()([)(tututtf，theevencomponentof)(tfis)(tfe＝，theoddcomponentof)(tfis)(tfo＝)]1()1()(2[2tututut（46％）)]1()1([2tutut（92％）5、Considerasignal)]1()([)(tututte，and)]1()([)(tutuetht，so)(*)(thte。(ExpressyouranswerbyrectangularwindowfunctionlikeI.4)先做微分其他,021),2(10,1)(1ttetettyt121e（76％）6、Necessaryandsufficientconditionsforstabilityofthesystemisitsimpulseresponse)(thshouldbe【int(f(x),-inf,inf)＝dxxf)(】dtth)(（37％）7、considerasignal)1()()(tutute，则)(*)(tete(ExpressyouranswerbyrectangularwindowfunctionlikeI.4))]2()1()[2()]1()([tututtutut（87％）,012,120,ttttothers8、KnownFouriertransformoff(t)is)(jF，sotheFouriertransformof)4(tfis。)(4jFej（71％）9、TheFouriertransformof)('2tetjis)2()(')('1)(2jtejtttj（83％）10、AsystemSwithinput][nxandoutput][nyrelatedby]}2[][]{[][ngngnxnyistimeinvariantwhile][ng=.Constant（6％）11、dxtyTtTttxt)()(),()()(,thenEof)(tyis2T（73％）II.Singlechoice(Totalscores24,eachscores6.)1.Theequivalentexpressionof)4(2tis(D)A：)2(21tB：)]2()2([21tt＋C：)2(41tD：)]2()2([41tt＋)0(0)(1)(ttdtt2.RefertotheFouriertransformof)()(tuetxat,todetermine)(tfwhentheFouriertransformof)(tfis)2(51j,then)(tfis(B)A：)()25(tuetjB：)()25(tuetjC：tje)25(D：tje)25(jatueat1)(3.Theinpute(t)andoutputr(t)ofacontinuoussystemisregulatedbyr(t)=e(t+2),thenthesystemis(D)A：causal,time-variant,linear,stableB：causal,time-invariant,nonlinear,unstableC：non-causal,time-variant,linear,stableD：non-causal,time-invariant,linear,stable4.Theinputf(t)andoutputr(t)ofasystemisgovernedbydeftr)()(,thenthesystemis(B)A:Linearandtime-invariantsystemB:Linearandtime-variantsystemC:Nonlinearandtime-invariantsystemD:Nonlinearandtime-variantsystemIII.TrueorFalse.(Totalscore16,eachscores2.)1.Ifsysteminputis)(tx,thenthesystem)()(ttxtyislinear.T2.Ifknh][(foranyn),andkisaknownconstant,thentheLTIsystemwithunitimpulseresponseh[n]isstable.F3.TheFouriertransformofrealevensignalisalsoarealevenfunction.T4.Foranysystem,theimpulseresponsecompletelydescribesitsbehavior.F5.Ifh(t)istheunitimpulseresponseofaLTIsystem,andh(t)isperiodicandnon-zero,thenthesystemisunstable.T6.Thesummationoftwoperiodicsignalsisalsoaperiodicsignal.F7.LTIsystemmustbecausal.F8.TheFouriertransformofarealoddsignalisapurelyimaginaryandoddfunctionoffrequency.T