Low cost infrared wireless ECG by using a simple sigma-delta modulation

In this paper a simple low cost measurement system of electrocardiogram (ECG) is presented. It is implemented by digitizing the measured ECG signal and then wireless (infrared) transmitting to be displayed the result on the computer screen. The analog-to-digital converter of the proposed method is based on a simple sigma-delta modulator. The main advantage of this circuit is that it has noise-shaping property. In addition, the employed sigma-delta modulator has an inherent clock signal. The external clock signal is therefore not required. The obtained sigma-delta output is sent to the receiver by the infrared driver circuit. The infrared wave received at the receiver is converted into an electrical signal and then passed through the low pass filter to recover the ECG signal. The reconstructed ECG signal is fed to the computer soundcard to be displayed on the screen. The experimental results show that the proposed system is fairly effective where the total harmonic distortion (THD) of system is lower than 0.08%.