sy14.m

数字信号处理工具箱

t=0:0.001:0.8;
x=sin(2*pi*50*t)+sin(2*pi*120*t);
y=x+1.5*randn(1,length(t));
plot(t,y);title('press any key ,continue');ylabel('时域波形');pause;
Y=fft(y,512);
P=Y.*conj(Y)/512;
f=1000*(0:255)/512;
plot(f,P(1:256));title('信号功率谱密度');xlabel('频率:Hz')