1、subplot(4,2,1);stem(n,A,fill);xlabel (时间序列nylabel(Asubplot(4,2,2);stem(n,B,时间序列n Bsubplot(4,2,3);stem(n,C,A+Bsubplot(4,2,4);stem(n,D,A-Bsubplot(4,2,5);stem(n,E,A.*Bsubplot(4,2,6);stem(n,F,A./Bsubplot(4,2,7);stem(n,G,A.B运行结果:(2)用MATLAB实现以下序列。a)x(n)=0.8n 0n15n=0:15;x=0.8.n;stem(n,x, xlabel (x(n)=0.8nb
2、)x(n)=e(0.2+3j)n 0n15x=exp(0.2+3*j)*n);x(n)=exp(0.2+3*j)*n)a)的时间序列 b)的时间序列c)x(n)=3cos(0.125n+0.2)+2sin(0.25n+0.1) 0n151:x=3*cos(0.125*pi*n+0.2*pi)+2*sin(0.25*pi*n+0.1*pi); xlabel(x(n)=3*cos(0.125*pi*n+0.2*pi)+2*sin(0.25*pi*n+0.1*pi)d)将c)中的x(n)扩展为以16为周期的函数x16(n)=x(n+16),绘出四个周期63;x=3*cos(0.125*pi*rem(
3、n,16)+0.2*pi)+2*sin(0.25*pi*rem(n,16)+0.1*pi);x16(n)e)将c)中的x(n)扩展为以10为周期的函数x10(n)=x(n+10),绘出四个周期39;x=3*cos(0.125*pi*rem(n,10)+0.2*pi)+2*sin(0.25*pi*rem(n,10)+0.1*pi);x10(n)d)的时间序列 e)的时间序列(3)x(n)=1,-1,3,5,产生并绘出下列序列的样本。a)x1(n)=2x(n+2)-x(n-1)-2x(n)3;x=1 -1 3 5;x1=circshift(x,0 -2);x2=circshift(x,0 1);x
4、3=2*x1-x2-2*x;stem(x3,x1(n)=2x(n+2)-x(n-1)-2x(n)b)x1=circshift(x,0 1);x2=circshift(x,0 2);x3=circshift(x,0 3);x4=circshift(x,0 4);x5=circshift(x,0 5);xn=1*x1+2*x2+3*x3+4*x4+5*x5;stem(xn,x2(n)=x(n-1)+2x(n-2)+3x(n-3)+4x(n-4)+5x(n-5) a)的时间序列b)的时间序列(4)绘出时间函数的图形,对x轴、y轴图形上方均须加上适当的标注。 a) x(t)=sin(2t) 0t10s
5、 b) x(t)=cos(100t)sin(t) 0t4sclc;t1=0:0.001:10;t2=0:0.01:xa=sin(2*pi*t1);xb=cos(100*pi*t2).*sin(pi*t2);subplot(2,1,1);plot(t1,xa);tx(t)title(x(t)=sin(2*pi*t)subplot(2,1,2);plot(t2,xb);x(t)=cos(100*pi*t2).*sin(pi*t2)(5)编写函数stepshift(n0,n1,n2)实现u(n-n0),n1n0=0;xlable(ylable(u(n-n0)2请输入终点:8请输入阶跃位置:6 (5)
6、运行结果 (6)运行结果(6)给一定因果系统求出并绘制H(z)的幅频响应与相频响应。a=1 -0.67 0.9;b=1 sqrt(2) 1;h w=freqz(b,a);fp=20*log(abs(h);plot(w,fp);xlabel(时间序列t幅频特性xp=angle(h);plot(w,xp);相频特性(右上图)常用典型序列单位采样序列function x,n=impseq(n1,n2,n0) n=n1:n2; x=(n-n0)=0;x,n=impseq(-2,8,2);stem(n,x);电信1201)n0=-2;n=-10:10;nc=length(n);x=zeros(1,nc)
7、;for i=1:nc if n(i)=n0 x(i)=1 endendstem(n,x) ;电信1201 采样序列第二种方法单位阶跃序列function x,n=stepseq(n1,n2,n0) x=(n-n0)x,n=stepseq(-2,8,2);实数指数n=0:x=0.9.n;复数指数序列alpha=-0.1+0.3*j;x=exp(alpha*n);real_x=real(x); image_x=imag(x);mag_x=abs(x); phase_x=angle(x);subplot(2,2,1); stem(n,real_x) ;subplot(2,2,2); stem(n,
8、image_x);subplot(2,2,3); stem(n,mag_x);subplot(2,2,4); stem(n,phase_x);正余弦x=3*cos(0.1*pi*n+pi/3);例: 求出下列波形x1(n)=2x(n-5)-3x(n+4)function y,n=sigadd(x1,n1,x2,n2) n=min(min(n1),min(n2) : max(max(n1),max(n2); y1=zeros(1,length(n); y2=y1; y1(find(n=min(n1)&(n=min(n2)&=max(n2)=1)=x2; y=y1+y2;function y,n=sigshift(x,m,n0) n=m+n0; y=x; n=-2:x=1:7,6:-1:1;x11,n11=sigshift(x,n,5);x12,n12=sigshift(x,n,-4);x1,n1=sigadd(2*x11,n11,-3*x12,n12);stem(n1,x1);已知某一系统方程为:yn-yn-1+0.9yn-2=xn计算并画出脉冲响应h(n),n=(-20,100)n=(-20:100);num=(1); den=1 -1 0.9;x=impseq(-20,100,0);h=filter(num,den,x);stem(n,h)时间序号N脉冲响应h
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