文档介绍：n=l:l:50;x=cos(*pi*n);y=cos(*pi*n)+*randn(1,50);subplot(2,2,l)stem(n,x)subplot(2,2,2)stem(n,y)l=l:l:5;xl=2*nl-l;n2=2:l:6;x2=2*n2・2;[y1,n3]=sigadd(xLn1,x2,n2);[y2,n4J=sigmult(xl,n1,x2,n2);n0=2;[y3,n5]=sigshift(x1,n1,n0);[y4,n6]=sigfold(x2,n2);subplot(2,2,l)stem(n3,yl)subplot(2,2,2)stem(n4,y2)subplot(2,2,3)stem(n5,y3)subplot(2,2,4)stem(n6,y4)function[Xzw]=ftl(x,n,k)w=(pi/abs(max(k)/2))*k;X=x*(exp(-j*pi/abs(max(k)/2))).A(n'*k);function[y,ny]=ft2(x,nx,z,nz)%定义通用卷积函数ft2nys=nx(1)+nz(1);nyf=nx(end)+nz(end);y=conv(x,z);ny=nys:nyf;x=-10:10;x=(-*exp(li*pi*4/3)).Anx;k=-200:200;[Xzw]=ftl(x,nx,k);subplot(3,1,1)plot(w/pi,X)gridxlabel(rfrequencyinpiunits1)ylabel('/X/')title(1X(e(j*w)1)nyl=nx;wO=pi;yl=x.*exp(j*wO*nyl);[Ylzw]=ftl(yl,nyl,k);subplot(3,1,2)plot(w/pi,Yl)gridxlabel(1frequencyinpiunits1)ylabel('/Yl/')title(fX(e(j*(w-wO)1)[y,ny]=ft2(x,nx,yl,nyl);[Y,w]=ftl(y,ny,k);subplot(3,1,3)plot(w/pi,Y)gridxlabel(1frequencyinpiunits1)ylabel('/Y/')title(-时域卷积后的频域特性')=[1,--];b=[,];subplot(2,2,1);若绘制单位取样响应图impz(bza);subplot(2,2,2);%绘制零极点图zplane(bza);[Hzw]=freqz(b,a);%计算频率响应subplot(2,2,3);plot(w/pi,abs(H));gridxlabel(1frequencyinpiunits1)title(*幅频响应,)ylabel(1Magnitude1)subplot(2,2,4)plot(w/pi,angle(H));gridxlabel(1frequencyinpiunits1)title('相频响应')ylabel(1Radians1)=[10,50,100];forr=l:3fs=fsO(r);f=20;n=(0:1/fs:1)';x=cos(2*pi*f*n+pi/2);t=linsp