njit-etd2003-081 - New Jersey Institute of Technology

272
B.2.3.4 Program to Generate SympathoVagal Activity Plots Using Wigner
Distribution This .m MATLAB program calculates the vagal tone and sympatho-vagal
ratio. It is an implementation of time-frequency analysis using the Wigner distribution.
The MATLAB code for the program is given below:
function symparl(rawdata,top)
% SYMPAR1(iibi,gtitle)
% iibi is the interpolated interbeat interval calculated
% by pslwsu, either in Matlab or in S-plus. Gtitle is the
% title of the output graphs.
% Written by Sanjay Fernando.
% last revision: 7/16/01 by Douglas Newandee (MATLAB 6.)
rawdata=rawdata(:);
order=5;
freq=0.03;
sample=20;
nfreq=freq/sample;
dtrendata=rawdata;
[row,col]=size(dtrendata);
I=1:row;
I=I(:);
A=(I/sample)/60;
% This part is for testing Janse Kaiser Wigner calculation
% algorithm with no window
fs=1000;
m=512; % The size of the fft we will be computing.
skip=25; % Number of points we skip to get the next segment.
p=60; % The number of freq vals we will be plotting
k=fix((row-m)/skip); % the number of spectra we compute
w=ones(size(1:m)); % window specification. Can be changed.
w=w(:);
x=hilbert(dtrendata); % Forms the analytic function of x
L=m/2;
l=-(L-1):(L-1);
n=L;