my6.m

DFT进行频谱分析时的三种现象 1、混叠：对连续信号采样

n=[0:1:29];
xn=cos(3*pi/20*n);
gn=[xn,zeros(1,30)];
N=length(n);
M=N+30;
m=[0:1:M-1];
Xk=fft(xn,30);
Gk=fft(gn,60);
subplot(2,1,1);
stem(n,abs(Xk));
title('frequence domain signal(n=30)');
axis([0,60,0,10]);
subplot(2,1,2);
stem(m,abs(Gk));
title('frequence domain signal(n=60)');