tfrpwv.rar_Cohen 时频_raise976_wigner cohen_牵制

function [tfr,t,f] = tfrpwv(x,t,N,h,trace); %TFRPWV Pseudo Wigner-Ville time-frequency distribution. % [TFR,T,F]=TFRPWV(X,T,N,H,TRACE) computes the Pseudo Wigner-Ville % distribution of a discrete-time signal X, or the % cross Pseudo Wigner-Ville representation between two signals. % % X : signal if auto-PWV, or [X1,X2] if cross-PWV. % T : time instant(s) (default : 1:length(X)). % N : number of frequency bins (default : length(X)). % H : frequency smoothing window, in the time-domain, % H(0) being forced to 1 (default : Hamming(N/4)). % TRACE : if nonzero, the progression of the algorithm is shown % (default : 0). % TFR : time-frequency representation. When called without % output arguments, TFRPWV runs TFRQVIEW. % F : vector of normalized frequencies. % % Example: % sig=fmlin(128,0.1,0.4); tfrpwv(sig); % % See also all the time-frequency representations listed in % the file CONTENTS (TFR*) % F. Auger, May-August 1994, July 1995. % Copyright (c) 1996 by CNRS (France). % % 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 should have received a copy of the GNU General Public License % along with this program; if not, write to the Free Software % Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA [xrow,xcol] = size(x); if (nargin < 1), error('At least 1 parameter is required'); elseif (nargin <= 2), N=xrow; end; hlength=floor(N/4); hlength=hlength+1-rem(hlength,2); if (nargin == 1), t=1:xrow; h = tftb_window(hlength); trace=0; elseif (nargin == 2)|(nargin == 3), h = tftb_window(hlength); trace=0; elseif (nargin == 4), trace = 0; end; if (N<0), error('N must be greater than zero'); end; [trow,tcol] = size(t); if (xcol==0) | (xcol>2), error('X must have one or two columns'); elseif (trow~=1), error('T must only have one row'); elseif (2^nextpow2(N)~=N & nargin==5), fprintf('For a faster computation, N should be a power of two\n'); end; [hrow,hcol]=size(h); Lh=(hrow-1)/2; h=h/h(Lh+1); if (hcol~=1)|(rem(hrow,2)==0), error('H must be a smoothing window with odd length'); end; tfr= zeros (N,tcol) ; if trace, disp('Pseudo Wigner-Ville distribution'); end; for icol=1:tcol, ti= t(icol); taumax=min([ti-1,xrow-ti,round(N/2)-1,Lh]); tau=-taumax:taumax; indices= rem(N+tau,N)+1; tfr(indices,icol) = h(Lh+1+tau).*x(ti+tau,1).*conj(x(ti-tau,xcol)); tau=round(N/2); if (ti<=xrow-tau)&(ti>=tau+1)&(tau<=Lh), tfr(tau+1,icol) = 0.5 * (h(Lh+1+tau) * x(ti+tau,1) * conj(x(ti-tau,xcol)) + ... h(Lh+1-tau) * x(ti-tau,1) * conj(x(ti+tau,xcol))) ; end; if trace, disprog(icol,tcol,10); end; end; tfr= fft(tfr); if (xcol==1), tfr=real(tfr); end ; if (nargout==0), tfrqview(tfr,x,t,'tfrpwv',h); elseif (nargout==3), f=(0.5*(0:N-1)/N)'; end;