Development of Electrocardiograph Monitoring System

Electrocardiograph (ECG) monitoring system is one of the diagnostic tools which can help in reduce the risk of heart attack. A cardiologist may be able to determine heart condition from the ECG signal that recorded from subject. The purpose was to design an ECG monitoring system which consists of ECG circuit and digital signal processing system to deny the unwanted signal. In general, the ECG signal is nature weak and only around 1mV amplitude. Therefore filter and amplifier circuits were designed into 3 stages with a total gain of 1000 to bring the signal to around 1V. Circuit designed included of instrumentation amplifier, bandpass filter and notch filter. The frequency bandwidth of ECG is between 0.05Hz until 100Hz. Schematic circuit was tested by software simulation before proceeding to hardware implementation. Simulation analysis was done by using Software Proteus 8 Professional while the further signal processing was done in MATLAB software environment. A PQRST ECG waveform can be seen clearly after digital filtering stage in MATLAB environment. Digital signal processing in MATLAB software included of pre-filtering, Fast Fourier transform and peak detection. As conclusion, the time interval between peaks can be determined automatically which can provide useful information in clinical aspect.