** analog **
  Find onset points using analog signal.
  * Slope
    = low_to_high : Find points that analog signal exceed the specified level.
    = high_to_low : Find points that analog signal goes under the specified level.
  * Level
    Threshold value (0-1). The maximum signal value is normalized to 1.

** integer **
  Find onset points using bit pattern.
  * Slope
    = const_start : Find points that the given bit pattern appears.
    = const_end   : Find points that the given bit pattern disappears.
  * Bit pattern
     bit pattern. (e.g. 1010)

  Trigger adjustment parameter <optional>
  * Data offset
    offset value of data(double).
  * Bit mask
    binary mask pattern for data.
       e.g.
         '11111111' : get lower 8 bit (high->low)

** bit **
  Find onset points using bit number.
  * Slope
      = low_to_high : Find points that specified bit turn on.
      = high_to_low : Find points that specified bit turn off.
  * Bit number
     Check Nth-bit(from 0)

  Trigger adjustment parameter <optional>
  * Data offset
    offset value of data(double).
  * Bit mask
    binary mask pattern for data.
       e.g.
         '11111111' : get lower 8 bit (high->low)

** multi channel pattern **
  Find onset points that signal changes to the given multi channel bit pattern.
  Choose channel list from Extra channel list.
  * Slope
    = const_start : Find points that the given channel bit pattern appears.
    = const_end   : Find points that the given channel bit pattern disappears.
  * Channel pattern
    A List of channel name & pattern(ON/OFF)
      e.g. ch430 : ON
           ch431 : OFF
           ch432 : ON
** emg **
  Find onset points using emg signal.

  * Optional parameter
     t_event      : minimum distance from previous onset event   [500 ms]
     t_period     : minimum period that Smoothed EMG > threshold [50 ms]
     status_level : threshold value control rate                 [1.0]

  * Advanced parameter(Usually they need not be changed)
    t_smooth : moving average window length                 [25 ms]
    p_val    : P-value corresponding to threshold value     [0.001] 
               If the signal exceeds the threshold, 
               the probability, that the signal is noise, is less than p_val

  * Suggestion for optional parameters
    (a)If too many EMG onsets are extracted, try to increase 't_event'
    (b)If some of onsets are not extracted, 
       try smaller status_level and/or shorter 't_period'
    (c)If false onsets with small peaks are extracted,
       try larger status_level and/or longer 't_period'

  * Procedure
    1.Smoothed EMG is calculated by moving average of abs(EMG)
      with time window length of 't_smooth' (20ms)
    2.Gamma distribution is fitted to the peak mode of EMG histogram 
    3.Default threshold value (y0) is determined from estimated gamma distribution
    4. Threshold value yh = y0 * status_level
    5. EMG power is calculated by TKE operator
       1) band-pass filtering at 30-300 Hz
       2) y(t) = x(t)^2 - x(t-1)x(t+1)     (TKE operator)
       3) low-pass filtering at 50 Hz 
    6. EMG onsets are extracted where EMG power exceed the threshold value

  * Condition for EMG onset (vb_get_emg_onset_time.m)
    1. Period length that EMG power exceed the threshold is larger than 't_period'
    2. Distance from previous onset should be larger than 't_event'

** voice **
  Find voice onset time that smoothed signal exceed the specified level.

  * Optional parameter
      t_period     : minimum period length that SA exceeds the threshold [100 ms]
      status_level :  threshold value control rate                       [1.0]

  * Advanced parameter
      t_smooth : moving average window length            [10 ms]
      p_val    : P-value corresponding to the threshold  [0.0001]

  * Procedure
    1. Smoothed amplitude (SA) is calculated by moving average of abs(signal) 
       with time window length of t_smooth (10ms : 100Hz)
    2. Gamma distribution is fitted to the SA histgram 
    3. Default threshold value (y0) is determined from estimated gamma distribution
    4. Threshold value yh = y0 * status_level
    5. Voice onsets are extracted where SA exceed the threshold

  * Condition for voice onset (vb_get_voice_onset.m)
    1. Period length that SA exceed the threshold is larger than 't_period'
