%fft的應(yīng)用
t=0:0.01:1;         %采用周期為0.001s,即采樣頻率為1000Hz
%產(chǎn)生受噪聲污染的正弦波信號(hào)
x=sin(2*pi*100*t)+sin(2*pi*200*t)+rand(size(t));
subplot(2,1,1),plot(x(1:50));
Y=fft(x,512);
f=1000*(0:256)/512;
subplot(2,1,2),plot(f,Y(1:257));