shiyulisan.txt

仅供学习中的朋友进行matlab实验指导书的教学实验源代码

t=0:0.1: 50;
A=5;
a=0.05;
w0=2*pi;
f0=w0/(2*pi);
fs=5;
Ts=1/fs;
xt=A*exp(-a*t).*sin(w0*t);
subplot(3,1,1);
plot(t,xt);
axis([0 max(t) 1.1*min(xt) 1.1*max(xt)]);
title('原信号');
n=0:Ts:10;
xn=A*exp(-a*n).*sin(w0*n);
subplot(3,1,2);
stem(n,xn,'filled');
axis([0 max(n) 1.1*min(xn) 1.1*max(xn)]);
title('抽样信号');
N=length(n);
n=0:(N-1);
w=linspace(-2*pi,2*pi,100);
Fn=xn*exp(-j*n'*w);
subplot(3,1,3);
plot(w/(2*pi),abs(Fn));
axis([-1 1 1.1*min(abs(Fn)) 1.1*max(abs(Fn))]);
title('抽样信号傅氏变换');
n1=0;n2=10;
n=n1:n2;
xb=[n==0];
subplot(4,1,1);
stem(n,xb,'filled');
axis([n1 n2 0 1.1*max(xb)]);
title('xb(n)=δ(n)');
x1=[(n-1)==0];
x2=[(n-2)==0];
x3=[(n-3)==0];
hb=xb+2.5*x1+2.5*x2+x3;
subplot(4,1,2);
stem(n,hb,'filled');
axis([n1 n2 0 1.1*max(hb)]);
title('hb(n)=δ(n)+2.5δ(n-1)+2.5δ(n-2)+δ(n-3)'); 
y=conv(xb,hb);
n=0:length(y)-1;
subplot(4,1,3);
stem(y,'filled');
title('y(n)=xb(n)*hb(n)');
N=length(y);
n=0:(N-1);
w=linspace(-2*pi,2*pi,500);
Y=y*exp(-j*n'*w);
subplot(4,1,4),plot(w,abs(Y));
title('Y|ejw|');