Project_scripts

% Essential parameters
fs = 240;
Ts = 1/fs;
data = load ('ECG1.txt');

% Time vector
t = 0 : Ts : ((length(data)-1)*Ts);

% Noise
fNoise = 50;    % Frequency [Hz]
aNoise = 0.25;  % Amplitude
noise  = aNoise*sin(2*pi.*t.*fNoise);

% Loading data from the file

x = data(:, 1)';
y = data(:, 2)';

%Addition of the noise to the original signal

signalNoise = y + noise;

% Plot of noisy signal

figure(1)
subplot(2,1,1)
plot(x, signalNoise, ';Signal with noise ;');
title('ECG Signal', 'FontSize', 20);
xlabel('Time', 'FontSize', 20);
ylabel('Voltage', 'FontSize', 20);
grid on;
subplot(2,1,2)
signalNoise_fft = fft(signalNoise);
stem(abs(signalNoise_fft)(1:250))
title('ECG Signal', 'FontSize', 20);
xlabel('Frequency', 'FontSize', 20);
ylabel('Magnitude', 'FontSize', 20);
set(gca, 'xTickLabel', 0:24:120);

% Plot of original signal

figure(2)
subplot(2,1,1)
plot(x, y, ';Original signal;');
title('ECG Signal', 'FontSize', 20);
xlabel('Time', 'FontSize', 20);
ylabel('Voltage', 'FontSize', 20);
grid on;
subplot(2,1,2)
y_fft = fft(y);
stem(abs(y_fft)(1:250))
title('ECG Signal', 'FontSize', 20);
xlabel('Frequency', 'FontSize', 20);
ylabel('Magnitude', 'FontSize', 20);
set(gca, 'xTickLabel', 0:24:120);

% Comparison of noisy and original signal

figure(3)
plot(x, signalNoise, ';Signal with noise ;');
hold on
plot(x, y, ';Original signal;');
title('ECG Signal', 'FontSize', 20);
xlabel('Time', 'FontSize', 20);
ylabel('Voltage', 'FontSize', 20);
grid on;
hold off;

% Plot of Notch filter

figure(4)
fs2 = fs / 2;
[b,a] = pei_tseng_notch (50 / fs2, 2/fs2);
filtered = filter(b,a,signalNoise);
subplot (2,1,1)
plot(filtered, ';Notch filter;');
title('ECG Signal', 'FontSize', 20);
xlabel('Time', 'FontSize', 20);
ylabel('Voltage', 'FontSize', 20);
grid on;
subplot (2,1,2)
notch_fft = fft(filtered);
stem (abs(notch_fft)(1:250))
title('ECG Signal', 'FontSize', 20);
xlabel('Frequency', 'FontSize', 20);
ylabel('Magnitude', 'FontSize', 20);
set(gca, 'xTickLabel', 0:24:120);

% Plot of FIR filter

figure(5)
f1 = 50/(fs/2) - 0.03;
f2 = 50/(fs/2) + 0.03;
c = fir1(100,[f1 f2], "stop" );
filtered2 = filter(c,1,signalNoise);
subplot (2,1,1)
plot(filtered2(1,50:500), ';FIR filter;');
title('ECG Signal', 'FontSize', 20);
xlabel('Time', 'FontSize', 20);
ylabel('Voltage', 'FontSize', 20);
grid on;
subplot (2,1,2)
fir_fft = fft (filtered2);
stem (abs(fir_fft)(1:250));
title('ECG Signal', 'FontSize', 20);
xlabel('Frequency', 'FontSize', 20);
ylabel('Magnitude', 'FontSize', 20);
set(gca, 'xTickLabel', 0:24:120);

% Comparison of Notch and FIR filter

figure(6)
plot(filtered2(1,50:500), ';FIR filter;');
title('ECG Signal', 'FontSize', 20);
xlabel('Time', 'FontSize', 20);
ylabel('Voltage', 'FontSize', 20);
grid on;
hold on
plot(filtered, ';Notch filter;');
title('ECG Signal', 'FontSize', 20);
xlabel('Time', 'FontSize', 20);
ylabel('Voltage', 'FontSize', 20);
hold off