%產(chǎn)生信號(hào)序列
n=linspace(-pi,pi,1024);
x=2*sin(n*40)+cos(n*100);
figure,plot(x);
title('輸入信號(hào)');
%計(jì)算序列的DFT
y1=fft(x);
figure,plot(abs(y1));
grid on
title('頻譜');
%計(jì)算序列的PSD
y2=conj(y1);
Ppw=y1.*y2/length(n);
%繪圖
figure,plot(Ppw);
grid on
title('周期圖法功率譜估計(jì)(直接法)');