Mercurial > hg > ltpda
diff m-toolbox/classes/@ao/lcohere.m @ 0:f0afece42f48
Import.
author | Daniele Nicolodi <nicolodi@science.unitn.it> |
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date | Wed, 23 Nov 2011 19:22:13 +0100 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/m-toolbox/classes/@ao/lcohere.m Wed Nov 23 19:22:13 2011 +0100 @@ -0,0 +1,139 @@ +% LCOHERE implement magnitude-squadred coherence estimation on a log frequency axis. +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +% +% DESCRIPTION: LCOHERE implement coherence estimation on a log frequency axis. +% The estimate is done by taking +% the ratio of the CPSD between the two inputs, Sxy, divided by +% the product of the PSDs of the inputs, Sxx and Syy, +% and is either magnitude-squared: (abs(Sxy))^2 / (Sxx * Syy) +% or complex value: Sxy / sqrt(Sxx * Syy) +% Here x is the first input, y is the second input +% +% CALL: b = lcohere(a1,a2,pl) +% +% INPUTS: a1 - input analysis object +% a2 - input analysis object +% pl - input parameter list +% +% OUTPUTS: b - output analysis object +% +% <a href="matlab:utils.helper.displayMethodInfo('ao', 'lcohere')">Parameters Description</a> +% +% VERSION: $Id: lcohere.m,v 1.30 2011/04/08 08:56:18 hewitson Exp $ +% +% References: "Improved spectrum estimation from digitized time series +% on a logarithmic frequency axis", Michael Troebs, Gerhard Heinzel, +% Measurement 39 (2006) 120-129. +% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +function varargout = lcohere(varargin) + + % Check if this is a call for parameters + if utils.helper.isinfocall(varargin{:}) + varargout{1} = getInfo(varargin{3}); + return + end + + import utils.const.* + utils.helper.msg(msg.PROC3, 'running %s/%s', mfilename('class'), mfilename); + + if nargout == 0 + error('### lcohere cannot be used as a modifier. Please give an output variable.'); + end + + % Collect input variable names + in_names = cell(size(varargin)); + for ii = 1:nargin,in_names{ii} = inputname(ii);end + + % Collect all AOs + [as, ao_invars] = utils.helper.collect_objects(varargin(:), 'ao', in_names); + + % Apply defaults to plist + pl = applyDefaults(getDefaultPlist, varargin{:}); + + % Throw an error if input is not two AOs + if numel(as) ~= 2 + error('### lcohere only accepts two inputs AOs.'); + end + + % Compute coherence with lxspec + scale_type = find(pl, 'Type'); + switch lower(scale_type) + case 'c' + bs = ao.lxspec(as, pl, 'cohere', getInfo, ao_invars); + case 'ms' + bs = ao.lxspec(as, pl, 'mscohere', getInfo, ao_invars); + otherwise + error(['### Unknown coherence type: [' scale_type ']']); + end + + % Set output + varargout{1} = bs; + +end + +%-------------------------------------------------------------------------- +% Get Info Object +%-------------------------------------------------------------------------- +function ii = getInfo(varargin) + if nargin == 1 && strcmpi(varargin{1}, 'None') + sets = {}; + pl = []; + else + sets = {'Default'}; + pl = getDefaultPlist(); + end + % Build info object + ii = minfo(mfilename, 'ao', 'ltpda', utils.const.categories.sigproc, '$Id: lcohere.m,v 1.30 2011/04/08 08:56:18 hewitson Exp $', sets, pl); + ii.setModifier(false); + ii.setArgsmin(2); +end + +%-------------------------------------------------------------------------- +% Get Default Plist +%-------------------------------------------------------------------------- + +function plout = getDefaultPlist() + persistent pl; + if ~exist('pl', 'var') || isempty(pl) + pl = buildplist(); + end + plout = pl; +end + +function pl = buildplist() + + % General plist for Welch-based, log-scale spaced spectral estimators + pl = plist.LPSD_PLIST; + + % Type + p = param({'Type',['type of output scaling. Choose from:<ul>', ... + '<li>MS - Magnitude-Squared Coherence:<br><tt>(abs(Sxy))^2 / (Sxx * Syy)</tt></li>', ... + '<li>C - Complex Coherence:<br><tt>Sxy / sqrt(Sxx * Syy)</tt></li></ul>']}, {1, {'C', 'MS'}, paramValue.SINGLE}); + pl.append(p); + +end + +% PARAMETERS: +% +% 'Kdes' - desired number of averages [default: 100] +% 'Jdes' - number of spectral frequencies to compute [default: 1000] +% 'Lmin' - minimum segment length [default: 0] +% 'Win' - the window to be applied to the data to remove the +% discontinuities at edges of segments. [default: taken from +% user prefs] +% Only the design parameters of the window object are +% used. Enter either: +% - a specwin window object OR +% - a string value containing the window name +% e.g., plist('Win', 'Kaiser', 'psll', 200) +% 'Olap' - segment percent overlap [default: -1, (taken from window function)] +% 'Type' - type of output scaling. Choose from: +% MS - Magnitude-Squared Coherence (abs(Sxy))^2 / (Sxx * Syy) +% C - Complex Coherence Sxy / sqrt(Sxx * Syy) [default] +% 'Order' - order of segment detrending +% -1 - no detrending +% 0 - subtract mean [default] +% 1 - subtract linear fit +% N - subtract fit of polynomial, order N