I would like to calculate heart rate by determining threshold for amplitude

I'd like to determing the QRS complex and draw rectange pulse and calculating hart rate

this code is what i write,

ecg =importdata ('ecg.txt');

sig=ecg(1:1400);

th=0.5;

count=0;

while (ecg> th)

count=count+1

end

[Star Strider]

The file contains only what appears to be a Lead II EKG, without an accompanying time vector or sampling frequency.

How are you going to calculate the heart rate without knowing the sampling times of the EKG trace?

[mary keshtkar]

I have no more information.

What if I just detect the QRS complex and count them?

[Star Strider]

See my Answer to your other Question. (There are still problems.)

Answer 1

[Image Analyst]

Try this:

% Optional initialization steps
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 18;
ecg = importdata ('ecg.txt');
% Plot it
hFig = figure('Name', "Mary's ECG Signal", 'NumberTitle','off');
plot(ecg, 'b-', 'LineWidth', 2);
grid on;
xlabel('Sample Number', 'FontSize',fontSize);
ylabel('Signal Value', 'FontSize',fontSize)
title("Mary's ECG Signal", 'FontSize',fontSize)
% Define threshold
threshold = 0.5;
% Draw red lines across the thresholds.
yline(threshold, 'Color','r', 'LineWidth', 2);
yline(-threshold, 'Color','r', 'LineWidth', 2);
% Detect samples above threshold
inAPositivePeak = ecg > threshold;
% Count the number of positive peaks using bwlabel() in the Image Processing Toolbox.
[~, numPositivePeaks] = bwlabel(inAPositivePeak)
% Detect samples below a threshold
inANegativePeak = ecg < -threshold;
% Count the number of positive peaks using bwlabel() in the Image Processing Toolbox.
[~, numNegativePeaks] = bwlabel(inANegativePeak)

numPositivePeaks =

67

numNegativePeaks =

67