Home > utils > physio > biopac_correct_calibration.m

biopac_correct_calibration

PURPOSE ^

correct a biopac waveform collected with incorrect calibration

SYNOPSIS ^

function EEG = biopac_correct_calibration(EEG,defs)

DESCRIPTION ^

 correct a biopac waveform collected with incorrect calibration
 
   EEG = biopac_correct_calibration(EEG,defs)
 
 This script currently only corrects scr that was not calibrated (i.e. the
 calibration settings were the default settings).
 
 REQUIRES
   EEG - an EEGlab data structure
   defs.biopac_correct_calibration.gain - gain setting of amplifier
   defs.biopac_correct_calibration.channel - name of channel
 
 RETURN
   EEG - an EEGlab data structure, with the given signal having been
   filtered
 
 FB 2009.06.10

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function EEG = biopac_correct_calibration(EEG,defs)
0002 
0003 % correct a biopac waveform collected with incorrect calibration
0004 %
0005 %   EEG = biopac_correct_calibration(EEG,defs)
0006 %
0007 % This script currently only corrects scr that was not calibrated (i.e. the
0008 % calibration settings were the default settings).
0009 %
0010 % REQUIRES
0011 %   EEG - an EEGlab data structure
0012 %   defs.biopac_correct_calibration.gain - gain setting of amplifier
0013 %   defs.biopac_correct_calibration.channel - name of channel
0014 %
0015 % RETURN
0016 %   EEG - an EEGlab data structure, with the given signal having been
0017 %   filtered
0018 %
0019 % FB 2009.06.10
0020 
0021 channel = defs.biopac_correct_calibration.channel;
0022 if iscell(channel), channel = channel{1}; end
0023 cidx = strmatch(channel,{EEG.chanlocs(:).labels});
0024 if isempty(cidx)
0025   error('target channel %s can not be found within EEG.chanlocs\n',...
0026       channel);
0027 elseif length(cidx) > 1
0028   warning('many channels match target channel %s, using first one\n',...
0029       channel);
0030   cidx = cidx(1);
0031 end
0032 
0033 switch channel
0034   case {'scr','gsr'}
0035     try gain = defs.biopac_correct_calibration.gain; catch gain = []; end
0036 
0037     if ~isempty(gain)
0038       EEG.data(cidx,:) = EEG.data(cidx,:)*gain;
0039     else
0040       error('no gain provided for SCR calibration');
0041     end
0042   otherwise
0043     warning('unknown channel %s',channel);
0044 end

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