Figure 2
From: Noncontact assessment for fatigue based on heart rate variability using IR-UWB radar
Digital signal processing algorithm for the HRV extraction using IR-UWB radar. (A) In the first phase, clutter and background subtraction were removed to make raw signal more appropriate for an accurate vital sign measurement. Next, fast Fourier transform (FFT) and a band pass filter was applied to raw data to obtain respiration and heartbeat signal. (B) In the second phase, Heart rate variability (HRV) was measured from the heartbeat rate by detecting R-R interval. A parametric method was applied on the R-R interval to estimate power spectral density (PSD) and find HRV components including LF and HF. The LF/HF ratio was calculated to index the states of rest, fatigue and recovery.
