www.gusucode.com > 语音信号处理工具箱 - Voicebox源码程序 > Voicebox\lpcar2db.m
function db=lpcar2db(ar,np) %LPCAR2DB LPC: Convert AR coefs to power spectrum in dB DB=(AR) % Copyright (C) Mike Brookes 1998 % % Last modified Fri Apr 3 14:57:15 1998 % % VOICEBOX 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 % ftp://prep.ai.mit.edu/pub/gnu/COPYING-2.0 or by writing to % Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% [nf,p1]=size(ar); if nargin<2 np=p1-1; end ff=rfft(ar.',2*np+2).'; db=-10*log10(real(ff.*conj(ff))); if nargout==0 plot((0:np+1)/(2*np+2),db.'); ylabel('dB'); end