【精品】《信号与系统》习题答案

《【精品】《信号与系统》习题答案》由会员上传分享，免费在线阅读，更多相关内容在工程资料-天天文库。

1、Chapter1ProblemsLISketchthewaveformoffollowingsignals.1.f(t)=(2-e~l)u(t)cos^r[u(t-l)-u(t-2)]4.f(t)=e~2M1-2below.1.allwareformshownasf(t)=—f+1[w(/+2)—u(t—2)]i-IoosLGf(t)=u(t+1)+u(t-0.5)+火一1.5)炉（£一圮）e（g-J+/£）7jt3=e（t7+D°；hee（t7+z）0/：Jp0；：；，卜祕7=炉（°；T）0/丁£0>勺0

2、（°J一“£（彳）并（二卩（°/一丿）。（彳一J.乙lj88f=卩（必（勺-"/Ji•iej§a）ui8沖joanjBA8P«HS-I•

3、^uoSoqyojouojb心屮[10]1BAJ9JUI。屮UOW屮os认o°'T=i血or="Pi,:JOOJd•[VO]代心遡叫aqiuouoipunjjEuoSoqyoajex6x仪气JdqpqAiSuiuiJ^dQ{?•[vCU=IUU主IU:JOOJJ0乙ipi（u一w/）soo+K"+必）so。]I—=jpjusoomisoof竝J[I•（n乙'o）lBAJ9）u!uouoipunjleuo

4、Soqjjooje）uso"・・・6）so3£oipJdqpqAiSuiuijapQ£・【[匕-7）刃-（为]令=IL[（丄一加一（》7]o）y=（“/i-=7〃=丄”用屮OS=J£(3r2+r-5)J2^r-

5、jdt=丄匸⑶$+—5)/(/-3)力=-[3—+--5]24213TE-加tfe[5(/十丄)+5(/—』)]df22=2cos—L2o1-6Thevvareformoff(t)isdepictedasbelow,pleasesketchthewaveformoff(t-3),f(-2t-l).Solution:f(-2t-l)1

6、-7f(t)asshownasFig•Tryingtosketchthewaveformoffollowingsignals.1.f(3t)2.3.中⑴4.L8Plotthewareformofgivendiscretesignals.ioJ_."o'Lul122.（—2门心）3.n-w(n)z*A4.s45zn兀71、cos()105/o*//X/♦■■、S、、■■1厂1//■■••丿2乡耳与占—、X、丄y/1-9Calculatetheconvolutionoff}(t)andf2(t)1./e=u(t),f2(t)=u(t)Z(O*

7、72(0=rfi(M(t-r)drJ—oo=£U(T)U(t-T)dlu{t)=fidru(t)Jo=tu(t)2.ZW=u(t),/；(/)=严火)川r(甘匸加-必如=Je~aTu(T)u(t-r)dr=^e~aTdrw(r)0=—e~aTu(t)at—JTw(r)-w(r-3)Ju{t—T)dT=2J。e~rdru(t)一2[e~Tdru(t-3)=2—e2〔幺'_e1Ju(t—3)2-2e'r2(1-/)0

8、X(n)=cos—n2071LetX⑺+AQ二cos两(/?+N)(兀71Kr.=cos(—n-N)202071N=40=cos—n20=X(n)SotheperrodisN=40,,nJT7T2X(n)=Sa(——+_)402LetX(ri+N)—sin(11)40240SotheperiodisN=801-11Findthewaveformofthefi【(t)J17T71、=sin(1——)402f2(t)(a)Solution:f1(t)=u(t)-u(t-1),fi(t)*f2(t)=J2f2(r)ff(t-T)dr=JT[u(

9、z)-u(r-2)][u(t-2)-u(t-r-1)]dTf—1TdTu(t-l)-TdTu(t-2)+=I{Jordru(t)・TdTu(t-3)}上[liu(t).曰帕)•(匚2)吩2)]+[凹・2]u(H)22222OrcalculatebymeansofgraghWesee(1)0

10、

11、

12、t

13、〈1andf2(t)=g(t+2)+5(t-2)bytheconvolutiondefining,wehavefi(t)*f2(t)=[fo(t+2)+fo(t-2)]*[力