# how to contaminate ecg signal with noise

18 views (last 30 days)
sai lakshmi on 16 Nov 2019
Commented: Daniel M on 23 Nov 2019
I am working on the project namely "FALSE ALARM REDUCTION IN ATRIAL FIBRILLATION DETCTION USING DEEP BELIEF NETWORKS".
In this i need to download two databases, namely 07910m.mat{MIT_BIH ATRIAL FIBRILLATION DATABASE} which is attached here,and also the 'em' recording {MIT_BIH NOISE STRESS TEST DATABASE} is attached.
The afib database has Fs=250Hz and 10h in length,and 'em' recording is 30 min and has Fs=360Hz
now i need to make the 'em' recording 10h in length
in the paper its told that i can be done using auto regressive model,iam not knowing how to do it
can anyone suggest me the coding for this
sai lakshmi on 20 Nov 2019
x1=(val(1,:))/200;
n=length(x1);
fs=250;
t=0:1/fs:(n-1)/fs;
%plot(t,x1);
%[qrs_amp_raw,qrs_i_raw,delay]=pan_tompkin(x1,fs,0);
x2=(val(1,:));
Fs=360;
x3=resample(x2,25,36);
figure(1);
subplot(2,1,1);
plot(x2);
subplot(2,1,2);
plot(x3);
[d1,p1,rc] = aryule(x3,20);
for c=1:20
psi(c)=d1(c+1);
end
zmwn=randn(size(x1));
z=double.empty(0,1000000);
for i=1:length(x1)
z(i)=(-1.8909*z(i-1)+1.2973*z(i-2)-0.7229*z(i-3)+0.4524*z(i-4)-0.2636*z(i-5)+0.2620*z(i-6)-0.2307*z(i-7)+0.2164*z(i-8)-0.8175*z(i-9)+0.1536*z(i-10)-0.1285*z(i-11)+0.0878*z(i-12)-0.0736*z(i-13)+0.0682*z(i-14)-0.0679*z(i-15)+0.0487*z(i-16)-0.0268*z(i-17)+0.0249*z(i-18)-0.0153*z(i-19)+0.0026*z(i-20))+zmwn(b);
end
I am getting an error "subscript indices must be either of positive values or logicals"
I understood the occurence for error,but am not recognizing of how to simulate the noise signal in this.

Daniel M on 20 Nov 2019
Edited: Daniel M on 21 Nov 2019
I obviously cannot run this code because I don't have the data nor any of the associated functions. By the way, you are getting an error because you are trying to access z at negative index locations.
Here is an example of how you would plot the equation. Keep in mind the assumptions I've made, which I've tried to comment.
clearvars
clc
sz = [1 1000];
e = randn(sz); % epsilon
X = nan(sz); % preallocate
X(1) = 0; % set first value. Don't know what this should be.
c = 1; % a constant, don't know what this should be
p = 5; % set the order of the model. Don't know what this should be.
% note that p cannot be greater than the iterating variable of the loop
% otherwise, it would try to access negative index locations
% So, either initialize your loop index at a value greater than 2 (and have the starting values of X)
% or do it this way, using increasing values of p, up to n-1
phi = rand(1,p); % your values of phi
for n = 2:sz(2)
ii = 1:min(p,n-1); % see the note above
sigma = dot(phi(ii), X(n-ii)); % sum of the products of the elements
X(n) = c + sigma + e(n);
end
Daniel M on 23 Nov 2019
Did you not see my response that phi must be << than 1? Did you even try it? It works.

sai lakshmi on 21 Nov 2019
I have provided the databases at the top of the question as links,please check it once and provide me with the required coding.
Daniel M on 22 Nov 2019
I think you're looking for a consultant.