用Matlab繪制波形

N=1024;

fs=1024;

t=0:1/fs:(N-1)/fs;

x=sin(200*pi*t);

%原始波形

figure

plot(t,x)%%%波形

set(gca,'xlim',[0,0.2],'ylim',[-1.3,1.3])

title('原始波形圖')

%頻譜分析

a=fft(x);

a=abs(a)*2/N;

f=0:fs/N:(N-1)*fs/N;

figure

plot(f,a)

title('幅頻譜圖')

%逆變換後時域圖

b=ifft(a)*N/2;

figure

plot(t,b)

set(gca,'xlim',[0,0.2],'ylim',[-1.3,1.3])

title('反變換後波形')