phaselock.m

Matlab时频分析工具箱,希望能对大家有所帮助啊

function cout = phaselock(cin,a)
%PHASELOCK  Phaselock Gabor coefficients
%   Usage:  c=phaselock(c,a);
%
%   PHASELOCK(c,a) phaselocks the Gabor coefficients c. The coefficient must
%   have been obtained from a DGT with parameter a.
%
%   Phaselocking the coefficients modifies them so as if they were obtained
%   from a time-invariant Gabor system. A filter bank produces phase locked
%   coefficients.
%
%   Phaselocking of Gabor coefficients correspond to the following transform:
%   Consider a signal f of length L and define N=L/a and b=L/M.
%   The output from c=PHASELOCK(DGT(f,g,a,M),a) is given by
% 
%                  L-1 
%     c(m+1,n+1) = sum f(l+1)*exp(-2*pi*i*(m*b-n*a)*l/L)*conj(g(l-a*n+1)), 
%                  l=0  
% 
%   where m=0,...,M-1 and n=0,...,N-1 and l-an is computed modulo L.

% 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 3 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, see <http://www.gnu.org/licenses/>.

%
%   SEE ALSO: DGT IPHASELOCK SYMPHASE
%
%R  puc95

%   AUTHORS : Peter Balazs
%             Peter Soendergaard.

error(nargchk(2,2,nargin));

if  (prod(size(a))~=1 || ~isnumeric(a))
  error('a must be a scalar');
end;

if rem(a,1)~=0
  error('a must be an integer');
end;

M=size(cin,1);
N=size(cin,2);
L=N*a;
b=L/M;

if rem(b,1)~=0
  error('Lattice error. The a parameter is probably incorrect.');
end;

TimeInd = (0:(N-1))*a;
FreqInd = (0:(M-1))/M;

phase = FreqInd'*TimeInd;
phase = exp(2*i*pi*phase);

% Handle multisignals
cout=zeros(size(cin));
for w=1:size(cin,3)
  cout(:,:,w) = cin(:,:,w).*phase;
end;