fig7_13.m

数字信号处理Matlab演示文件,其中各个文件加放置了不同的matlab子文件

%	Figure 7.13
%       min phase & mixed phase
%
%	BM
%       Oct 1994

clear
clf
colordef(1,'white')

z = zeros(2,4);
z(:,1) = [ 1/2 1/3]';
z(:,2) = [ 1/2 3 ]';
z(:,3) = [ 2 1/3 ]';
z(:,4) = [ 2 3 ]';
p = [ 0 0 ]';

for ii=1:4,
	[b,a] = zp2tf(z(:,ii),p,1);
	num(:,ii) = b';
	den(:,ii) = a';
	sigma = sqrt( num(:,ii)' * num(:,ii) );
	num(:,ii) = num(:,ii)/sigma;
	[h(:,ii),w] = freqz(num(:,ii),den(:,ii),128);
	amp(:,ii) = 10*log10( abs(h(:,ii)));
	phs(:,ii) = angle(h(:,ii))/pi*180;
	end
w = w/pi*.5;
rr = 48:128;
subplot(211),plot(w,amp(:,1))
xlabel('normalised frequency'), ylabel ('gain (dB)')
subplot(212),plot(w,phs(:,1),w,phs(:,2),w,phs(:,3),w(rr),phs(rr,4))
xlabel ('normalised frequency'), ylabel('phase shift (degrees)')
%gtext('min phase')
%gtext('max phase')