Matlab EMG信号处理：on/off检测算法

function onoff = emgonoff(rawemg, fs, ws, sd)
% EMGONOFF - Find on/off times and indicies of raw EMG data.
% Calculate average(mean) value of resting EMG
% Define "on" EMG as the sample where average value of EMG in a given window
% range around the sample is a given # of std. dev. above avg. resting EMG.
%
% onoff = emgonoff(rawemg, fs, ws, sd)
%
% Use the mouse to select two ranges of "resting" EMG from a graph of the
% full-wave rectified EMG data.  Click four times: start and end of 1st
% resting range, and start and end of 2nd resting range.  Mouse clicks need
% to be consecutive and in order of increasing time (i.e. left-to-right on
% the graph).  The first range should precede the EMG burst associated with
% the muscle contraction under consideration.  The sedond range should be 
% the resting EMG data immediately following the EMG burst.
%
% rawemg = input file raw emg data (1-column vector)
% fs = sampling rate of raw EMG data in Hz
% ws = window size in milliseconds (50ms @ 2400Hz = 120 samples)
% sd = number of std. deviations above resting rms emg to trigger an "ON"
% Default values: 
%   ws = 50ms
%   sd = 1

% Algorythm for EMG onset & offset taken from 
% Hodges, P.W. and B.H. Bui, _A comparison of computer-based methods for 
% the determination of onset of muscle contraction using electromyography._ 
% Electroencephalography & Clinical Neurophysiology, 1996. 101(6): p. 511-9
%
% Created by: Kieran A. Coghlan, BSME, MSES