fg_07_18a.m

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

% fg_07_18         PDS of filtered Gaussian noise - changing K.
sp_fig(1);
set(gcf,'defaultaxesfontname','times');
set(gcf,'defaultaxesfontsize',16);

N=2^10; NH=500; y2=2; K=[64,32,16];
randn('seed',12345);
x=randn(1,N);
[b,a]=ch_weights(3,8,-40,.1,.4);
H=abs(gain(b,a,NH)).^2;
y=filters(b,a,x);

subplot(1,3,1); k=K(1);
[p,Nsg]=pds(y,y,k,1,.95);
bar2([0:k/2]/k,p(1:k/2+1),'k'); grid on;
h=line([0:NH-1]*.5/NH,H,'color','k','linewidth',1.5);
axis([0 .5 0 y2]);
xlabel('\nu (Hz-s)'); ylabel('Power density, P_y(\nu)');
title(['K=',int2str(k)]);

subplot(1,3,2); k=K(2);
[p,Nsg]=pds(y,y,k,1,.95);
bar2([0:k/2]/k,p(1:k/2+1),'k'); grid on;
h=line([0:NH-1]*.5/NH,H,'color','k','linewidth',1.5);
axis([0 .5 0 y2]);
xlabel('\nu (Hz-s)'); title(['K=',int2str(k)]);

subplot(1,3,3); k=K(3);
[p,Nsg]=pds(y,y,k,1,.95);
bar2([0:k/2]/k,p(1:k/2+1),'k'); grid on;
h=line([0:NH-1]*.5/NH,H,'color','k','linewidth',1.5);
axis([0 .5 0 y2]);
xlabel('\nu (Hz-s)'); title(['K=',int2str(k)]);