An enhanced non-contact heart rate measurement in a 24GHz doppler radar system

Abstract

The technology of vital signs detection for the heart rate measurement using a Doppler radar system has been proven of great use, whereas it is still limited by several challenges. The major challenges are respiratory harmonic interference and random body movement (RBM), which significantly degrade the accuracy of measurement. In this paper, a novel vital signs detection method is proposed to acquire accurate heart rate measurement by jointly exploiting the respiratory harmonic cancellation method and regional hidden Markov model (RHMM) technique. The complex signal demodulation technique is firstly used to acquire an accurate respiratory rate estimation, and the respiration harmonic cancellation method is then introduced to address the harmonic interference. Finally, the RHMM technique is utilized to acquire robust and enhanced heart rate measurement by exploiting the underlying slowly-varying characteristics of the heartbeat signal to mitigate the effects of RBM. Experimental results based on a 24 GHz Doppler radar system show that the proposed method has a better performance than previous methods, whose average accuracy of the heart rate measurement reaches up to 94.5% in the RBM environment.