vb_get_emg_onset

 Find EMG onset time using smoothed EMG signal
    [ix ,zd, z] = vb_get_emg_onset(y, parm)
    [ix ,zd, z, ix_y, yd, ix_z, ix_s] = vb_get_emg_onset(y, parm)
 --- Input
 y             : EMG signal
 parm  : parameter structure
 parm.fsamp    : sampling frequency [Hz]
 --- Optional parameter for EMG onset
 parm.t_event  : minimum distance from previous onset event [500 ms]
 --- Usually following parameters need not be changed
 parm.t_smooth : moving average window length                 [10 ms]
 parm.t_period : minimum period that Smoothed EMG > threshold [50 ms]
 parm.p_val : P-value corresponding to the threshold for [smooth(EMG)] 
             =  [0.001] 
 --- Condition for EMG onset
 1. Smoothed EMG (yave) should exceed 'z0' more than 't_period' length
 2. Distance from previous onset should be larger than 't_event'

 --- Output
 ix   : extracted onset time index
 zd   : smoothed EMG threshold value
 z    : smoothed EMG by moving average
 ix_y : abs(EMG) onset time index
 yd   : threshold for abs(y)     
 ix_z : smoothed EMG onset     
 ix_s : start & end of slope estimation region at jx

 2009-09-05 Masa-aki Sato
 2012-2-18  Masa-aki Sato 
   Use TKE operator EMG filter
 2012-2-22  Masa-aki Sato 
   threshold determination is changed

 Copyright (C) 2011, ATR All Rights Reserved.
 License : New BSD License(see VBMEG_LICENSE.txt)

0001 function    [ix ,zd, z, ix_y, yd, ix_z, ix_s] = vb_get_emg_onset(y,parm)
0002 % Find EMG onset time using smoothed EMG signal
0003 %    [ix ,zd, z] = vb_get_emg_onset(y, parm)
0004 %    [ix ,zd, z, ix_y, yd, ix_z, ix_s] = vb_get_emg_onset(y, parm)
0005 % --- Input
0006 % y             : EMG signal
0007 % parm  : parameter structure
0008 % parm.fsamp    : sampling frequency [Hz]
0009 % --- Optional parameter for EMG onset
0010 % parm.t_event  : minimum distance from previous onset event [500 ms]
0011 % --- Usually following parameters need not be changed
0012 % parm.t_smooth : moving average window length                 [10 ms]
0013 % parm.t_period : minimum period that Smoothed EMG > threshold [50 ms]
0014 % parm.p_val : P-value corresponding to the threshold for [smooth(EMG)]
0015 %             =  [0.001]
0016 % --- Condition for EMG onset
0017 % 1. Smoothed EMG (yave) should exceed 'z0' more than 't_period' length
0018 % 2. Distance from previous onset should be larger than 't_event'
0019 %
0020 % --- Output
0021 % ix   : extracted onset time index
0022 % zd   : smoothed EMG threshold value
0023 % z    : smoothed EMG by moving average
0024 % ix_y : abs(EMG) onset time index
0025 % yd   : threshold for abs(y)
0026 % ix_z : smoothed EMG onset
0027 % ix_s : start & end of slope estimation region at jx
0028 %
0029 % 2009-09-05 Masa-aki Sato
0030 % 2012-2-18  Masa-aki Sato
0031 %   Use TKE operator EMG filter
0032 % 2012-2-22  Masa-aki Sato
0033 %   threshold determination is changed
0034 %
0035 % Copyright (C) 2011, ATR All Rights Reserved.
0036 % License : New BSD License(see VBMEG_LICENSE.txt)
0037 
0038 [yd, zd, z] = vb_get_emg_threshold(y, parm);
0039 
0040 if isempty(parm.status_level)
0041     zd = yd;
0042 else
0043     zd = yd * parm.status_level;
0044 end
0045 
0046 [ix ,ix_y, ix_z, ix_s] = vb_get_emg_onset_time(y , z ,yd, zd, parm);
0047 
0048 %[ix] = vb_emg_spectral_check(y,ix,parm);
0049 
0050 
0051 return