Abstract
Vital signs such as heart rate and respiration rate are among the most important physiological signals for health monitoring and medical applications. Impulse radio (IR) ultra-wideband (UWB) radar becomes one of the essential sensors in non-contact vital signs detection. The heart pulse wave is easily corrupted by noise and respiration activity since the heartbeat signal has less power compared with the breathing signal and its harmonics. In this paper, a signal processing technique for a UWB radar system was developed to detect the heart rate and respiration rate. There are four main stages of signal processing: (1) clutter removal to reduce the static random noise from the environment; (2) independent component analysis (ICA) to do dimension reduction and remove noise; (3) using low-pass and high-pass filters to eliminate the out of band noise; (4) modified covariance method for spectrum estimation. Furthermore, higher harmonics of heart rate were used to estimate heart rate and minimize respiration interference. The experiments in this article contain different scenarios including bed angle, body position, as well as interference from the visitor near the bed and away from the bed. The results were compared with the ECG sensor and respiration belt. The average mean absolute error (MAE) of heart rate results is 1.32 for the proposed algorithm.
Highlights
Heart rate and respiration rate are two important factors of human’s body health
Considering the advantages of Impulse radio (IR)-UWB radar in providing range information and higher signal-to-noise ratio (SNR), compared with Frequency modulated continuous wave (FMCW) or continuous wave (CW) radars, this study developed a signal processing approach for heart rate and respiration rate detection based on IR-UWB technology
The energy of heart rate harmonics is more than the energy of respiration harmonics in the heart rate harmonics related frequency ranges [8]; a comparison was made between the energy of independent components (IC) after high-pass filter (HPF), and the maximum energy IC was selected as the heart rate signal
Summary
Heart rate and respiration rate are two important factors of human’s body health. Resting heart rate can be a prognostic factor for coronary heart disease [1], and it highly relates to stroke, sudden death, and other non-cardiovascular diseases [2]. Researchers achieve multi-people heartbeat and respiration rate detection using the amplitude demodulation technique[7] There is another non-contact vital signs monitoring technique using radar sensors [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]. Considering the advantages of IR-UWB radar in providing range information and higher SNR, compared with FMCW or CW radars, this study developed a signal processing approach for heart rate and respiration rate detection based on IR-UWB technology.
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