信号与系统课后答案(西南交大).pdf

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1、习题1参考答案1.1①非周期信号②周期信号，周期为2③非周期信号④非周期信号2⑤周期信号，周期为0.5⑥周期信号，周期为π3⑦周期信号，周期为1⑧非周期信号11.2①功率信号P=②功率信号P=1③既不是功率信号也不是能量信号2④能量信号E=1⑤功率信号P=1⑥功率信号P=11.5(a)f(t)=u(t)+(t−1)u(t−1)+(4−2t)u(t−2)+(t−3)u(t−3)−u(t−4)(b)f(t)=tu(t)+(1−t)u(t−1)+(3−t)u(t−3)+(t−4)u(t−4)π(c)f(t)=f(t)[u(t−1)−u(t−2)],其中f

2、(t)=10cos(πt+)112(d)f(t)=tu(t)−2u(t−1)+(2−t)u(t−2)(e)f(k)=3[u(k+1)−u(k−5)]k(f)f(k)=(−1)[u(k+1)−u(k+5)]−100aδ(t)1.7①δ(t−2)②eδ(t−10)③④-1⑤0⑥421.10①线性系统②非线性系统③线性系统④线性系统⑤非线性系统⑥非线性系统⑦线性系统⑧非线性系统1.11①时变系统②非时变系统③时变系统④时变系统⑤非时变系统1.12①非线性，非时变，因果系统②线性，时变，因果系统系统③线性，时变，因果系统系统④线性，非时变，因果系统−2t1

3、.13y(t)=−2e+sin3tt≥0−2t−t1.14①y(t)=−6e+5et≥0f−2t−t②y(t)=−11e+10et≥0习题2参考答案2p+2p+1p+12.1①H(p)=②H(p)=322p+4p+5p+2p+5p+62.2①y′′′(t)+3y′′(t)+2y′(t)=f′(t)+4f(t)②y′′′(t)+4y′′(t)+8y′(t)=3f′(t)+f(t)2p+p+12.3H(p)=32p+2p+3p+22p+3p+22.4H(p)=22p+3p+23p2.5H(p)=2p+4p+4p(p+3)2.6H(p)=32p(p+2p

4、+2p+3)−t−2t−2t2.7y(t)=2e−2e−2tet≥0−t−3t−t2.8①y(t)=e−et≥0②y(t)=(1+t)et≥0xx−2tππ③y(t)=2ecos(2t−)t≥0④y(t)=2cos(3t−)t≥0xx44−t−2t⑤y(t)=20e−(17+10t)et≥0x−t−2t−t−3t2.9①y(t)=7e−5et≥0②y(t)=6e−(4+5t)et≥0xx−t−2t③y(t)=1.5−2e+0.5et≥0x−t−3t−t2.10①h(t)=(0.5e+0.5e)u(t)②h(t)=teu(t)3−2t1−t−2t−2

5、t③h(t)=esin(2t)u(t)④h(t)=sin(3t)u(t)⑤h(t)=(e−te−e)u(t)23−t−2t−3t2.11①h(t)=(−2e+2e)u(t)+δ(t)②h(t)=teu(t)−t−2t③h(t)=(2−3e+e)u(t)−2t−3t2.12①y(t)=2e−2et≥0x2−3t1-2t1y(t)=−e+e+t≥0f3268−3t5-2t1y(t)=−e+e+t≥0326−2t-3t②y(t)=2e−2et≥0x−2t−2t-3ty(t)=−te+2e−2et≥0f−2t-2t−3ty(t)=−te+4e−4et≥0⎧

6、12⎧12t1t0≤t<1t++-1≤t<0⎪⎪4636⎪⎪⎪2t−1⎪2t+12.14①⎨1≤t<2②⎨0≤t<2⎪4⎪622⎪−t+2t+3⎪−t+92≤t<32≤t<3⎪⎩4⎪⎩6−t-2t2.15①y(t)=3e−3et≥0x−t−2t②h(t)=(2e−e)u(t)+δ(t)1−2t-t5③y(t)=e−2e+t≥0f22−t5-2t5④y(t)=e−e+t≥022−t2.16①y(t)=1+3tet≥0−t②y(t)=1+(2+7t)et≥0−t③y(t)=(1+4t)et≥0−t④y(t)=(2+5t)et≥0−t1−2t52.17①

7、y(t)=2t+3e−e−t≥02223−t−2t1−3t②y(t)=−e+e−et≥0326−t−t2.18y(t)=−2te−e+t+1t≥012t1−t2.19y(t)=eu(−t)+eu(t)f3312t4−t−2t2.20y(t)=eu(−t)+(e−e)u(t)f33−t2.21y(t)=eu(t)f3111−2t2.22①tu(t)②∞③(t−+e)u(t)244sint+cost1−tt−2④(−e)u(t)⑤eu(t−3)+eu(3−t)⑥cos(ωt+45°)221−cosπtcosπt−112122.23①u(t)+u(t−2

8、)②tu(t)−(t−1)u(t−1)ππ2226−2t+10t+4t+3e−e③u(t+1)④u(t−2)22t2t⑤t