AR滤波器程序
本人刚接触这方面的知识，请教如何设计一个AR滤波器呀，具体程序谢谢！ 不明白楼主的AR滤波器是指什么，是在已知AR系数后进行反滤波（白化滤波）？ 就是白化滤波 本帖最后由 wdhd 于 2016-9-14 10:19 编辑原帖由 yll 于 2009-2-19 16:40 发表
就是白化滤波
下面给出了一个是从语音工具箱中得到的已知AR系数的反滤波函数，仅供参考：
function u=lpcifilt(s,ar,t,dc,fade)
%LPCIFILT Apply inverse filter to speech signal U=(S,AR,T,DC,FADE)
%
% Inputs: S speech signal
% AR(nf,p+1) array of ar coefficients; one row per frame
% T column vector giving the index of the first sample in each frame
% DC(nf) optional dc component will be subtracted from the signal
% FADE AR coefficients will be linearly interpolated for FADE samples
% either side of frame boundaries
%
% Example: estimate the 2nd derivative of glotttal flow from a speech signal sp with sample freq fs
%
% spp=filter(,1,sp); % preemphasis zero is at 50 Hz
% =lpcauto(spp,lpcord,floor(*fs)); % 20ms frame with 10ms frame increment
% overlap=k(1,2)-k(2,1)+1; % overlap between adjacent frames
% u=lpcifilt(sp,ar,k(:,1)+floor(overlap/2),0,overlap/4);% do inverse filtering
% Copyright (C) Mike Brookes 1997
% Version: $Id: lpcifilt.m,v 1.5 2007/07/18 17:41:49 dmb Exp $
%
% VOICEBOX is a MATLAB toolbox for speech processing.
% Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% This program is free software; you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation; either version 2 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
% GNU General Public License for more details.
%
% You can obtain a copy of the GNU General Public License from
% http://www.gnu.org/copyleft/gpl.html or by writing to
% Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
=size(ar);
if nargin<4 | isempty(dc)
dc=zeros(nf,1);
elseif length(dc)==1
dc=dc(ones(nf,1));
end
if nf==1
u=filter(ar,1,s-dc);
else
p=p1-1;
ns=length(s);
if nargin<5 | isempty(fade)
fade=0;
if nargin<3 | isempty(t)
t=p1+(0:nf-1)*(ns-p)/nf;
end
end
u=zeros(ns,1);
if fade<1
x0=(max(1,ceil(t(nf)-p)):ns)';
u(x0)=filter(ar(nf,:),1,s(x0)-dc(nf));
for i=nf-1:-1:2
x0=(max(1,ceil(t(i)-p)):ceil(t(i+1)-1))';
u(x0)=filter(ar(i,:),1,s(x0)-dc(i));
end
x0=(1:ceil(t(2)-1))';
u(x0)=filter(ar(1,:),1,s(x0)-dc(1));
else
tb=min(t(nf)+fade,(t(nf)+ns)/2);
ta=max(t(nf)-fade,(t(nf-1)+t(nf))/2);
t0=max(1,ceil(ta)-p);
x0=(t0:ns)';
xb=x0-tb;
u(x0)=filter(ar(nf,:),1,s(x0)-dc(nf)).*max((1+(xb-abs(xb))/(2*(tb-ta))),0);
for i=nf-1:-1:2
td=tb;
tc=ta;
tb=min(t(i)+fade,ta);
ta=max(t(i)-fade,(t(i-1)+t(i))/2);
t1=floor(td);
t0=max(1,ceil(ta)-p);
x0=(t0:t1)';
xb=x0-tb;
xc=x0-tc;
u(x0)=u(x0)+filter(ar(i,:),1,s(x0)-dc(i)).*max((1+(xb-abs(xb))/(2*(tb-ta))-(xc+abs(xc))/(2*(td-tc))),0);
end
t1=floor(tb);
x0=(1:t1)';
xc=x0-ta;
u(x0)=u(x0)+filter(ar(1,:),1,s(x0)-dc(1)).*(1-(xc+abs(xc))/(2*(tb-ta)));
end
end
回复
谢谢！AR滤波器都有什么功能？
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