mtm.m

多频道功率谱计算程序

function [S,c]=mtm(x,W, method, conf); 
% Syntax: [S,c]=mtm(x,W); [S,C]=mtm(x,W,method,conf); 
% Mtm is a shell function, which implements the Thomson 
% multiple-taper method of spectral estimation for the 
% time series x, for window width W. W should be specified 
% as e. g. 2, 5/2, 3, 7/2, etc. W=4 is often a good choice 
% for the bandwidth - this is the default. 
% 
% There are two options for the estimation method ("method"): 
%   'lin'  : simple estimate with linear weights. 
%   'dap' : adaptively-weighted estimate. (default) 
% 
% The confidence level for the confidence limits can be 
% specified in 'conf'. The default is .95 (95%). 
% 
% Output: The spectral estimate is returned in S, 
%         and confidence limits are returned in c. 
% 
% For more details, see dpss.m, dpssint.m, dpsscalc.m, 
% mtmlin.m, and mtmadap.m 
% 
% Written by Eric Breitenberger, version date 10/1/95. 
% Please send comments and suggestions to [e-mail] 
% 
 
if nargin==1, W=4; method='dap'; conf=.95; 
elseif nargin==2 
  if isstr(W), method=W; W=4; conf=.95; 
  elseif W<1, method='dap'; conf=W; W=4; 
  else method='dap', conf=.95; 
  end 
elseif nargin==3,  
  if ~isstr(method) 
    conf=method; method='dap'; 
  else, conf=.95; 
  end 
end 
 
% Get the dpss, one way or another: 
N=length(x); 
[E,V]=dpss(N,W); 
 
if method=='lin', 
  [S,c]=mtmlin(x,E,V); 
elseif method=='dap', 
  [S,c]=mtmadap(x,E,V); 
else 
  error('Improper specification of method.') 
end