《信号与系统》于慧敏著课后习题答案【khdaw_lxywyl】(1)

(P25-28)1.11-521.21)(ttu2]}2[][{−−nunun3)1()1(−−tut4]2[)21(2−−nun5)]1()([−−−tutuet6)2()2sin(π−π−tut(1)(2)(3)(4)(5)(6)1.3153(bdeu(t))(a))1()(2)1()(1−+−+=tutututxabcdef0t0t1n01231n012310.54560t110.3680t21-11t1-11-1x1(t)(a)x'1(t)2课后答案网(b)1||0|,|1)(2−=tttx(c))]1()1(sin[)(3−⋅−π=tuttx)1()1()(2)1()1()(2−−+−++=tutttututtx(d)≤≤−≤≤≤≤=43431110)(4ttttttx;(e)≤≤≤≤−≤≤≤≤=43132421101)(5tttttttx)4()4()3()3()1()1()()(4−−+−−+−−+=tuttuttutttutx)4()3()3()2()24()1()1()()(5−−−−+−−+−−+=tututtuttuttutx1.41-53(a)(b)(d)(e):1.51-541f(2t-1)2f(1-2t)3f(-t/2+1)4f(t)[(t+1)+(t-2)]:(1)(2)−≤≤−−=21)1(210)(01)(ttuttutttf0t13x3(t)(c)t11x4(t)(d)043x'4(t)t11f(2t)02-12t11f(-2t)02-12t11-1x2(t)(b)x'2(t)2t11x5(t)(e)043x'5(t)11t0.5f(2t-1)02-1211.52t11f(t)02-11-541.5t11f(1-2t)0-12课后答案网(3)4f(t)[(t+1)+(t-2)]1.6x(3-2t)1-55x(t)1.7x[n]1-56x(t)1x[n-3]2x[4-n]3x[2n+1]4x[n-3][n-3].1x[n-3]2t11f(t/2)02-14-22t1102-1t11x(-2t)02.5243/2x(-2t)x(2t)t1x(2t)02-2.50.5n-203121-0.5-10.5456tf(-t/2+1)0412-22t11x(3-2t)02241-551.6x(2t)2x(t)t1x(t)02-51-1-34n-2-1031210.5-0.51-561.7课后答案网[4-n]=x[-n+4]x[n]x[-n]x[-n+4]=x[-(n-4)]x[-n]x[-n+4]3x[2n+1]x[2n]()x[2n+1](0.5)41x[n-3][n-3](0)1.81)()sin()(1tuwttx⋅=2)()](sin[)(02tuttwtx⋅−=3)()sin()(03ttuwttx−⋅=4)()](sin[)(004ttuttwtx−⋅−=1)()sin()(1tuwttx⋅=2)()](sin[)(02tuttwtx⋅−=n-2-1031210.5-0.5-112-2n0-112-210.510.50.5-0.5n-203121-0.5-10.5456wtwtn-2-103120.5-0.5-3n2345160.5-0.517890-1课后答案网)()sin()(03ttuwttx−⋅=4)()](sin[)(004ttuttwtx−⋅−=1.91-57)()()(txtxtxoe+=)(txe)]()([21)(txtxtxe−+=)(txo)]()([21)(txtxtxo−−=(1)(2):][][][nxnxnxoe+=][nxe]}[][{21][nxnxnxe−+=][nxo]}[][{21][nxnxnxo−=t0wtt0wtt102x(t)(1)n-2-103121x[n]2-1-3-4(2)t102x(t)(a)x(t)t10-2x(-t)(b)x(-t)t102xo(t)(d)xo(t)-20.5-0.5t02xe(t)(c)xe(t)-20.5课后答案网][nxe][nxo)}1,21,21,12,11,21,12,12,1(21{][−+−+++++−−=nxe={0.50.51.51.511.51.50.50.5})}1,21,21,12,11,21,12,12,1{(21][−−−−−−−+−=nxo={0.51.50.5-0.500.5-0.5-1.50.5}1.10(1))34cos(3)(π+=ttx(2))1()(−=tetxπα(3))(]2[cos)(tuttxπ=(4)4/cos][nnx=(5))278cos(][+=nnxπ(6))2/cos)6/sin(3)4/cos(2][πππnnnnx−+=1242200πππ===wT2a)(tx34410=ωπωπ820=54720=ωπ7=T624=T1.11x1(t)x2(t)T1T2x1(t)+x1(t))(1tx1T)()(111Ttxtx+=)(2tx2T)()(222Ttxtx+=21TTmnTT=21)()(21txtx+21nTmTT==TT1T2n-2-103121x[-n]2-1-3-4(b)x[-n]1-14n-2-103121x[n]2-1-3-4(a)x[n]-1课后答案网=)(2]1[][][−=nxnxny3ddtdxty=)(4]1[]2[][+−−=nxnxny5)()4sin()(txtty=6]4[][nxny=1xtety=)(attbttc)(11)(txety=)(22)(txety=)()()(21)()(21tytyetytxtx+≠=+d)(11)(txety=)()(012ttxtx−=)()(01)()(2012ttyeetyttxtx−===−eMtx)(Mety)(2]1[][][−=nxnxnyan1−nbnnc]1[][][111−=nxnxny]1[][][222−=nxnxny]1[][][−=nxnxny][][][21nxnxnx+=][][])1[]1[])([][(][212121nynynxnxnxnxny+≠−+−+=d]1[][][111−=nxnxny]1[][][222−=nxnxny][][012nnxnx−=][]1[][][0101012nnynnxnnxny−=−−−=eMnx][2][Mny3ddtdxty=)(attxttxdttdxtyt∆−∆+==→∆)()(lim)()(0ttt∆+123456课后答案网)()(δ=0t0)(=thcdttdxty)()(11=dttdxty)()(22=dttdxty)()(=)()()(2211txatxatx+=)()()()()(22112211tyatyadttdxadttdxaty+=+=ddttdxty)()(11=)()(012ttxtx−=)()()()(010122ttydtttdxdttdxty−=−==e)()(tutx=)(tx)()()(tdttdxtyδ==4]1[]2[][++−=nxnxnyan2−n1+nbn1+nnc]1[]2[][111++−=nxnxny]1[]2[][222++−=nxnxny]1[]2[][++−=nxnxny][][][2211nxanxanx+=][][])1[]1[]2[]2[][221122112211nyanyanxanxanxanxany+=++++−+−=d]1[]2[][111++−=nxnxny][][012nnxnx−=][]1[]2[]1[]2[][010101222nnynnxnnxnxnxny−=−++−−=++−=eMnx][Mny2][5)()4sin()(txtty=attbttc)()4sin()(11txtty=)()4sin()(22txtty=)()()(2211txatxatx+=)()()()4sin()()4sin()()4sin()(22112211tyatyatxtatxtatxtty+=+==课后答案网)()4sin()(11txtty=)()4sin()(22txtty=)()(012ttxtx−=)()4sin()(012ttxtty−=)())(4sin()(01001ttxtttty−−=−eMtx)(Mty)(6]4[][nxny=ann4bnn40nn4nc]4[][11nxny=]4[][22nxny=][][][2211nxanxanx+=][][]4[]4[]4[][22112211nyanyanxanxanxny+=+==d]4[][11nxny=][][012nnxnx−=]4[]4[][0122nnxnxny−==)](4[][0101nnxnny−=−eMnx][Mny][1.13x[n]y[n]]2[][][−=nxnxny(1)(2)][nAδA1ny[n]nn-220]2[][]2[][][2=−δδ=−δδ=nnAnAnAny1.14Sx(t)y(t)tjetx2)(=tjety3)(=tjetx2)(−=tjety3)(−=(1)ttx2cos)(1=)(1ty(2))12cos()(2−=ttx)(2tySS课后答案网)(212cos)(221tjtjeettx−+==teetytjtj3cos)(21)(331=+=−2)(21)(21)12cos()(22)12()12(2tjjtjjtjtjeeeeeettx−−−−−+=+=−=)13cos()(21)(332−=+=−−teeeetytjjtjj1.15u[n]1-581-58P271]4[]1[][−−+=nununy2]}5[][{2)1(][−−+=nununny3]7[)142(]5[)28(]2[)24(][)22(][−−+−−+−−++=nunnunnunnunnx1.16(1)∫−−+++442)]1()()[23(dtttttδδ(2)∫−−−πππδdttt)2()cos1((3)∫−+ππδ22)(cos)1(dttt1862)1()0()]1()()[23(442=+=+=−+++∫−ffdtttttδδ21)2()2()cos1(==−−∫−ππδππfdttt34)1()1()1()1()(cos)1(23222322=+++++++=+−=−===−∫ππππππδttttttttdttt1.17)(21)2(ttδ=δ10≠t02≠t0)2(=tδ221)(21)2()()2(111121===∫∫∫∞∞−∞∞−=∞∞−dtttdtdttttδδδt=0)(21)2(ttδδ=1.18LTI)()(tutx=)1()()(tutuetyt−−+=−1-59)(tx)()(tutx=)1()()(tutuetyt−−+=−课后答案网)2()1()(1−−−=tututxLTI)2()1()(1−−−=tytyty)1()2()()1()()2()1(1tutuetutuetytt−−−−−+−=−−−−1.19LTI1-60a)(1tx)(1ty1-60b1-60c1-60d)(2tx)(3tx11-60c)2()()(112−−=txtxtxLTI)2()()(112−−=tytyty1-60c’21-60d)()1()(113txtxtx++=1)()1()(113tytyty++=1-60d’t102x1(t)1-60at202y1(t)1-60b12t10x2(t)1-60c42t11x3(t)02-11-60d1-60