jo_freqz.m

这是一个用于语音信号处理的工具箱

function [h,w] = johnfreqz(b,a,n,radius)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%	jmw
%	
%	sometime in early 1994 ...
%
%	a variation of freqz that calculates frequency response on a circle
%	that may or may NOT have a unit radius.
%
%	used in the McCandless Algorithm to "home in" on pole positions
%	by iteratively reducing the size of the circle that the 
%	frequency response is calculated on in the Z plane.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
a = a(:).';
b = b(:).';
na = max(size(a));
nb = max(size(b));
nn = max(size(n));
s = 2;

if nn == 1
	w = (2*pi/s*(0:n-1)/n)';
else
	w = n;
	n = nn;
end

a = [a zeros(1,nb-na)];  % Make sure a and b have the same length
b = [b zeros(1,na-nb)];
s = radius*exp(sqrt(-1)*w);
h = polyval(b,s) ./ polyval(a,s);