Fast heart rate extraction using CW Doppler radar with interpolated discrete Fourier transform algorithm

Abstract

Doppler radar-based fast heart rate (HR) extraction has great application potential in stress and emotion recognition, anxiety treatments, etc. However, fast extraction of HR is still a great challenge for the vital sign detection applying the traditional discrete Fourier transform (DFT) method based on a continuous-wave (CW) Doppler radar sensor. When applying traditional DFT to the baseband signal analysis, the spectrum resolution will become insufficient if the time window is less than 10 s. In this paper, an interpolated DFT algorithm based on a poly-item cosine window is introduced to achieve fast extraction of HR with only 3 s data length. In addition, the leakage and grid effect phenomenon is presented to show the defects caused by the traditional DFT method. To verify the effectiveness of the proposed method, simulations are performed and experiments are executed using a 10-GHz CW Doppler radar sensor platform. Compared with the traditional DFT method, the interpolated DFT method reduces the average HR error from 8.48% to 1.87% based on the Hanning window and from 8.48% to 1.45% based on the rectangular window.

Noncontact Cardiac Activity Detection Based on Single-Channel ISM Band FMCW Radar

“…Most radar-based cardiac motion studies focus on the periodicity of the heartbeat, such as heart rate or heart rate variability [26][27][28][45][46][47], and lack an analysis of the movement characteristics within a heartbeat cycle as shown in Table 3. Some studies have utilized the first-order and second-order derivatives of the heartbeat waveform to extract the velocity and acceleration waveforms, which are then compared to the synchronously measured ECG signal to identify matching features [22,48,49].…”

“…In [22], the respiratory waveform was determined through empirical formulas, and then it was removed from the measured signal to obtain the heartbeat signal and has achieved good results. Most studies on radar-based heartbeat signal measurement primarily focus on the average heart rate during the observation period [23][24][25][26][27][28], resulting in insufficient exploration of cardiac health information. Thus, it is necessary to conduct more in-depth research on the heartbeat signal to further uncover valuable insights into cardiac health.…”

An Improved Real-Time Detection Algorithm based on Frequency Interpolation

“…Compared with the traditional contact sensors, the CW Doppler radar possesses evident advantages, such as insensitive to light and temperature [22], availability to the patients with burn or skin disease [23], and good penetrability of electromagnetic wave that can pass through clothing [24].…”