Mean absolute value for ecg signal

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swetha r
swetha r 2020-5-10
编辑： Little Flower 2022-8-25
I have an ecg signal of total length 2500 samples with 250Hz sampling frequency. Now i need to find the Mean absolute value for the signal with 8s analysis window using the formula MAV =1/N summation ( 0 to N-1) of x(n). Can anyone help me with the code.
N=length(xrec); %xrec is my ecg signal
A=N/8;
Y=0;
for i=1:A
Y=Y+max(abs(xrec(i)));
end
MAV=(1/A)*Y;

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回答（1 个）

Thiago Henrique Gomes Lobato
Your code is okay with exception of the length. If you have a sampling rate of 250 Hz (or, in another way of expression, values per second) you need to multiply it by the number of seconds you want to obtain the signal length. Fixing your code look like this (also, repare in the lower implementation for a more efficient way to do it with matlab):
xrec = randn(2500,1);
Fs = 250;
N=length(xrec); %xrec is my ecg signal
A= 8*Fs; % 8 seconds times Fs
Y=0;
for i=1:A
Y=Y+max(abs(xrec(i)));
end
MAV=(1/A)*Y;
% more efficient way
MAV = mean(abs(xrec(1:A)));
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Thiago Henrique Gomes Lobato
Thiago Henrique Gomes Lobato 2020-5-10
The only thing missing from my first answer and your command is the normalization (step 2):
xrec = randn(2500,1); % replace for your signal and Fs
Fs = 250;
N=length(xrec); %xrec is my ecg signal
A= 8*Fs; % step 1
seg = xrec(1:A);
seg = seg/max(abs(seg)); % step 2
% Step 3
Y=0;
for i=1:A
Y=Y+max(abs(seg(i)));
end
MAV=(1/A)*Y;
% more efficient Step 3
MAV = mean(abs(seg(1:A)));
Little Flower
Little Flower 2022-8-25
编辑：Little Flower 2022-8-25
@Thiago Henrique Gomes Lobato
How to calculate Mean absolute value slope (MAVS) of a signal? It was given as the difference between the adjacent segments of mean absolute value (MAV). What does it mean ? Thanks in advance

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