JOSS_STEP_1.m

function [BPM, SSRsig, S, C] = SSR_JOSS(y, Fs, N)

if (nargin == 2)
% resolution is set to 1 BPM
N = 60*Fs;
end
Y=[y(1,:); y(3,:); y(4,:); y(5,:)];
Y=transpose(Y);
L = size(Y,2);
S = zeros(N,L);
for i = 1:L
[BPM, SS] = SSR(Y(:,i), Fs, N);
% normalize spectra
SS = SS / max(SS);
S(:,i) = SS;
end
aggression = 0.99;
C = zeros(1,N);
SSRsig = S(:,1);
for i = 1:length(BPM)
% max of acceleration at f_i
C(i) = max([S(i,2),S(i,3),S(i,4)]);
% spectral subtraction
SSRsig(i) = SSRsig(i) - aggression*C(i);
end
% set values smaller than 1/5-th of the max to 0
p_max = max(SSRsig);
SSRsig(SSRsig < p_max / 5) = 0;
end