Find onset time that signal exceed the threshold value 'y0'
ix = vb_trigger_onset_event(y,y0,ymax,twin,Nrate)
--- main input
y : analog signal
y0 : threshold value for 'y'
ymax : max value threshold within 'twin' period
twin : period length
Nrate: y should be larger than ymax for (twin*Nrate) samples
--- condition for onset
if 'twin' is not empty,
'y' shoud exceed 'ymax' for (twin*Nrate) samples within twin period
--- Output
ix : extracted onset time index
2011-12-16 Masa-aki Sato
2012-1-8 Masa-aki Sato
check exceptional cases
condition is changed
Copyright (C) 2011, ATR All Rights Reserved.
License : New BSD License(see VBMEG_LICENSE.txt)0001 function ix = vb_trigger_onset_event(y,y0,ymax,twin,Nrate) 0002 % Find onset time that signal exceed the threshold value 'y0' 0003 % ix = vb_trigger_onset_event(y,y0,ymax,twin,Nrate) 0004 % --- main input 0005 % y : analog signal 0006 % y0 : threshold value for 'y' 0007 % ymax : max value threshold within 'twin' period 0008 % twin : period length 0009 % Nrate: y should be larger than ymax for (twin*Nrate) samples 0010 % --- condition for onset 0011 % if 'twin' is not empty, 0012 % 'y' shoud exceed 'ymax' for (twin*Nrate) samples within twin period 0013 % --- Output 0014 % ix : extracted onset time index 0015 % 0016 % 2011-12-16 Masa-aki Sato 0017 % 2012-1-8 Masa-aki Sato 0018 % check exceptional cases 0019 % condition is changed 0020 % 0021 % Copyright (C) 2011, ATR All Rights Reserved. 0022 % License : New BSD License(see VBMEG_LICENSE.txt) 0023 0024 % find event start (at which signal exceed the threshold) 0025 ix = vb_trigger_start(y,y0); 0026 0027 if isempty(ix), return; end; 0028 if isempty(twin), return; end; 0029 if isempty(ymax), ymax = y0; end; 0030 if nargin < 5 || isempty(Nrate), Nrate = 0.8; end; 0031 0032 N = length(ix); 0033 T = length(y); 0034 0035 % time index for 'twin' period 0036 twin = round(twin); 0037 tt = 1:twin; 0038 0039 % # of samples to exceed 'ymax' within 'twin' period 0040 Ny = zeros(N,1); 0041 0042 for n=1:N 0043 t = min(ix(n) + tt,T); 0044 Ny(n) = sum(y(t) >= ymax); 0045 end 0046 0047 % 'y' shoud exceed 'ymax' for (twin*Nrate) samples within twin period 0048 jj = find(Ny >= Nrate*twin); 0049 0050 ix = ix(jj); 0051 0052 %ix = vb_onset_check(ix,twin); 0053