信号与系统陈后金版答案.ppt

21:(1)x()=[(t+1)-a()]-[()-(t-21:(2)x()=r(t+1)-r(t-1)-(t-1)+(t+1)x(t)x(t)2-1:(7)x()=e[u(t)-u(t-4)22:(2)x(t)=sin(xt/2)m(-123:(2)(r+22+3)6(t-2)=(8+8+3)6(-2)x(1)196(t-2)24:(4)sin(t)(t-T/4)dt=sin(t)ler/24:(5e-s(+)-0(-m)h=c-c-2jsin(aoT2-5:(4)x(t+1)x(t/3+12-9:x(1)=e[u(-1)-u(-2)+t6(t-3,求x(t),x(t)(1)=e[u(-1)-l(t-2)]+36(t-3()={e[(z-1)-u(x-2)+36(z-3)dx()=」ca(--u(z-2)z+3m(-3)0,t<1(z-1)-u(z-2)ddI1<t<2dIt>20,t<1,1<t<2t>2x-(1)=(el-e)[a(t-1)-u(t-2)+(el-e2)u(t-2)+3(-3)2-9)=1--2+13,x(,x(x()=eb(t-1)-0t-2)-e(t-1)-u(-2)+368(t-3)x'()=ebt-1)-e26(t-2)-e{u(-1)-l(t-2)+36(t-3)e[(t-1)-(t-2)+e6(-1)-c26(1-2)+36(-3)2-11:(3)x{k]=%{uk]-a[k-5]}=,0≤k≤4213:(3)x3k2-13:(43-2g(t)=r(t)-2r(t-1)+r(t-2)(t)=r(t)-r(t-1)g()=x"(t)根据系统积分特性:输入信号积分,输出也积分,有:(t)=y"()-y(t-1)=[(t+1)+u(t+2)-[(t-1)+u(t[(t+1)-[(t-1)+[u(t-2)-l(t-3)]yg(t)233-4已知离散时间LT系统输入xk=k-时,输出;yk]=()u4k-1],求当输入x2[k]=2k]+u{k时系统响应y2kxk]=2xk+1∑xk=2k+1]+∑xn+1y2k]=2yk+11+∑yn+y2k]=2()小+∑()dny2k=2()k+∑()”=[2+()1dkl3-14(1)6(t+1)+206(t-1)*[6(t-1)-6(-3)=6(t)+26(t-2)-6(t-2)-26(t-4)3-14(2)(t)-u(t-1)]*[(-2)-(t-3=r(-2)-r(t-3)-r(t-3)+r(t-4)r(t-2)-2r(-3)+r(t-4)3-20:y"(t)+7y(t)+10y(t)=2x(t)+3x(t);x(t)=eu(t);y(0)=1,y(O)=1解:1:求冲激响应h():输入x(t)=6(t),有:h"(t)+7h'(t)+10h(1)=2(t)+36(1),t≥0特征根为s1=-2,s2=-5,又因为n>m,所以:Wlh(t)=Keu(t)+K,eu(t)h(t)=-2Keu(t)+KS(t)-5Keu(t)+k,o(t)2ke(t)-5K2el(t)+(K1+K2)(t)h"(t)=4K1e(t)-2K1d(t)+25K2e(t)-5k2(t+(K1+K2)O()代入方程有:2K2()+5k∴K2=73:kx1=-1/32()+30(