电子科大信号与系统期中考试试卷及答案

学院姓名学号任课老师选课号/座位号………密………封………线………以………内………答………题………无………效……第1页共3页电子科技大学二零一零至二零一一学年第一学期期中考试SIGNALSANDSYSTEMS课程考试题卷（120分钟）考试形式：闭卷考试日期2010年月日课程成绩构成：平时10分，期中20分，实验10分，期末60分一二三四五六七八九十合计复核人签名得分签名Attention:eachofthefollowingquestionsmayhaveoneortworightanswers,justifyyouranswersandwriteitintheblank.1.ConsideranLTIsystemwhoseunitimpulseresponsehnaregivenby1nhnaunnan.Theoutputnhnxnyofthissystemis().(a)xn(b)1xn(c)1xn(d)1axn2.32322tetdt().(a)2e(b)212e(c)2e(d)212e3.ConsideranLTIsystemwhoseinputxnandunitimpulseresponsehnaregivenby2,0,1,1,0,1xnn，1,1,3,4,2,3,4,5hnn.Theoutputnhnxnyofthissystemis().(a)2,2,7,9,3,4,0,1,2,3,4,5ynn(b)2,2,7,9,3,4,1,2,3,4,5,6ynn(c)2,2,7,12,3,4,1,2,3,4,5,6ynn(d)2,2,7,9,3,4,1,0,1,2,3,4ynn4.Whichofthefollowingsignalhasthemosthighfrequency.()(a)cos2n(b)cos2n(c)cosn(d)3cos2n5.Thefundamentalfrequencyofthesignal)2sin()3cos()(tttxis().(a)0(b)02(c)30(d)046.Let111xttututand18kxtxttk.TheFourierseriescoefficientsofxtmaybe().(a)andIm0kkkaaa(b)andIm0kkkaaa(c)andRe0kkkaaa(d)andRe0kkkaaa7.ConsideranLTIsystemwithunitimpulseresponsehtillustratedinFigure1，iftheinputisxtut,theoutput1tytis().(a)1(b)-1(c)-0.5(d)0.5110122thtFigure11学院姓名学号任课老师选课号/座位号………密………封………线………以………内………答………题………无………效……第2页共3页8.Theconvolutionintegral2teut().(a)22teut(b)2teut(c)212teut(d)29.Whichofthefollowingsystemsisnotanlinearsystem.()(a)cos3yttxt(b)3tytext(c)lnytxt(d)22tytxd10.Acontinuous-timesignal24xtisillustratedinFigure2,theclosed-formexpressionforxtis().(a)1133xtuttuttut(b)2233xtuttuttut(c)3355xtuttuttut(d)2244xtuttuttut11.Consideracontinuous-timeLTIsystemwhosefrequencyresponseHjisillustratedinFigure3.Iftheoutputis2cos4ytt,theinputxtmaybe().(a)ktk(b)1/42ktk(c)/2ktk(d)1/22ktk12.Determinewhichofthefollowingsignalswithfinitetotalenergy().(a)21xnn(b)txtteut(c)1cos/32nxnnun(d),txtet13.Consideracontinuous-timeLTIsystemwhosefrequencyresponseHjisillustratedinFigure4.Iftheoutput)(tyisidentifiedtotheinputsignal)(tx,i.e.)()(txty,then)(txmaybe().(a)1cos6xtt(b)kkttx)41()((c)1cos3sin6xttt(d)1223kxttk14.Whichofthefollowingsystemsarecausalandstablesystem.()(a)cos2httut(b)2thteut(c)25thteutut(d)2thtteut15.Wearegivenacertainsystemwithunitimpulseresponse0htand000ytxtht.Whichofthefollowingstatementsaretrue.()(a)000xthtyt(b)000xthtyt(c)00022xthtyt(d)000dxtdythtdtdt《信号与系统》半期考试评分标准说明1012t24xtFigure201()Hj3553Figure301()Hj2442Figure4学院姓名学号任课老师选课号/座位号………密………封………线………以………内………答………题………无………效……第3页共3页一参考答案1.(c)2.(b)3.(b)4.(c)5.(a)6.(d)7.(b)8.(d)9.(c)10.(d)11.(a)、(d)12.(b)、(c)13.(a)、(b)14.(c)、(d)15.(b)、(d)二注意：1.本次半期考试总分为100分，评阅标准为：⑴若只填写了1个答案，正确得5分，错误得0分；⑵若填写了2个答案，2个正确得10分，1个正确、1个错误得5分，2个错误得0分；⑶若填写了3个答案，2个正确、1个错误得8分，1个正确、2个错误得3分，3个错误得0分；⑷若填写了4个答案，得0分。2.各位老师阅卷完成后请统计以下三个分段的人数：60分以下、60~80分以及80~100分。并请于三日之内将统计数据报到通信学院教务科。信号与系统课程组2010-10-30