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author
Daniele Nicolodi <nicolodi@science.unitn.it>
date
Mon, 05 Dec 2011 16:20:06 +0100 (2011-12-05)
parents
f0afece42f48
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+ − % PFALLPSYMZ2 all pass filtering to stabilize TF poles and zeros.
+ − %
+ − %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ − % DESCRIPTION:
+ − %
+ − % All pass filtering in order to stabilize transfer function poles and
+ − % zeros. It inputs a partial fraction expanded discrete model and
+ − % outputs a pole-zero minimum phase system
+ − %
+ − % CALL:
+ − %
+ − % resp= pfallpz2(ip,mresp,f,fs)
+ − %
+ − % INPUTS:
+ − %
+ − % ip: is a struct with fields named poles
+ − % mresp: is a vector with functions response
+ − % f: is the frequancies vector in (Hz)
+ − % fs: is the sampling frequency in (Hz)
+ − %
+ − % OUTPUTS:
+ − %
+ − % resp: is the stable functions frequency response
+ − %
+ − % NOTE:
+ − %
+ − %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ − % VERSION: $Id: pfallpz.m,v 1.6 2009/06/10 15:47:00 luigi Exp $
+ − %
+ − % HISTORY: 12-09-2008 L Ferraioli
+ − % Creation
+ − %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ − function varargout = pfallpsymz2(ip,mresp,f,fs)
+ −
+ − [a,b] = size(ip);
+ − if a<b
+ − ip = ip.'; % reshape as a column vector
+ − end
+ −
+ − [a,b] = size(f);
+ − if a<b
+ − f = f.'; % reshape as a column vector
+ − end
+ −
+ − if isempty(fs)
+ − fs = 1;
+ − end
+ − [a,b] = size(fs);
+ − if a ~= b
+ − disp(' Fs has to be a number. Only first term will be considered! ')
+ − fs = fs(1);
+ − end
+ −
+ −
+ − %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ − Nb = numel(ip);
+ − for nn = 1:Nb
+ −
+ − p = ip(nn).poles;
+ −
+ − % stabilizing poles
+ − sp = sym(p);
+ − unst = abs(p) > 1;
+ − sp(unst) = conj(sp(unst));
+ −
+ − pp = sym(p(unst));
+ − psp = sp(unst);
+ − syms z
+ − allpsym = 1;
+ − for jj=1:numel(psp)
+ − allpsym = allpsym.*((z-pp(jj))./(z*psp(jj)-1));
+ − end
+ − funcell{nn} = allpsym;
+ −
+ − end
+ −
+ − fullallprsp = 1;
+ −
+ − for nn = 1:Nb
+ − symexpr = funcell{nn};
+ − nterm = subs(symexpr,z,cos((2*pi/fs).*f) + 1i.*sin((2*pi/fs).*f));
+ − % willing to work with columns
+ − if size(nterm,2)>1
+ − nterm = nterm.';
+ − end
+ −
+ − fullallprsp = fullallprsp.*nterm;
+ −
+ − end
+ −
+ − % dballprsp = double(fullallprsp);
+ − % rallp = real(dballprsp);
+ − % iallp = imag(dballprsp);
+ − % ang = angle(dballprsp);
+ −
+ − for kk=1:Nb
+ − sresp(:,kk) = mresp(:,kk).*fullallprsp;
+ − % resp(:,kk) = mresp(:,kk).*(cos(ang)+1i.*sin(ang));
+ − end
+ −
+ − for kk=1:Nb
+ − resp(:,kk) = double(sresp(:,kk));
+ − end
+ −
+ −
+ − % output
+ − if nargout == 1
+ − varargout{1} = resp;
+ − else
+ − error('Too many output arguments!')
+ − end
+ − end
+ −
+ −
+ −
+ −