Cardiac activity detection: A fast prototyping approach with health safety considerations

This paper presents a fast prototyping approach for the construction of a Doppler radar system operating at 24-GHz ISM-Band for noncontact detection of cardiac activities. The hardware system consists of an off-the-shelf radar sensor, a signal conditioning board and a Notebook computer. A two-step dc offsets removal technique is exploited to measure the cardiac activities in arctangent demodulation procedure. Various health safety regulations (for subjecting human body to radar signals) have also been studied and the requirements for system design and operating conditions are proposed (to ensure that the system operates within the health safety regulations). Experiments involving stationary human subjects have been carried out. The results obtained show that, the cardiac waveform can be detected clearly and the heart rates can be measured with accuracy higher than 98% when the radar system operates at 0.5 meter away from the human subject.