fg_07_11.m

英文书《Digital Signal Processing with Examples in MATLAB》附带的MATLAB实例

% fg_07_11          Periodogram (bar version)
sp_fig(1,9,4);
N=100; M=50;
set(gcf,'defaultaxesfontsize',16);
set(gca,'position',[0.11 0.2 0.85 0.7]);

m=0:M-1; n=0:N-1;
b=exp(-m*4/M).*cos(2*pi*9*m/(2*M));
x=b*sin(2*pi*m'*(n-N/2)/N);
x=x/(1.1*max(x));

P=fftshift(abs(fft(x)).^2/N);
bar2(-1/2:1/N:1/2-1/N,P,'r'); grid on;
axis([-.5 .5 0 1.1*max(P)]);
xlabel('Frequency \nu (Hz-s)'); ylabel('         P(\nu)'); 
grid on;

dnu=1/N;
EP=sum(P*dnu)
Ex2=sum(x.^2)/N