Noncontact Pulse Transit Time Measurement Using a Single-Frequency Continuous-Wave Radar
This paper presents a single-frequency continuous-wave (CW) radar that operates concurrently with two different modes to measure pulse transmit time (PTT) without contact. One is self-injection-locked (SIL) CW mode to detect the wrist movement due to pulse. The other is the range-correlated (RC) CW mode to detect the chest movement due to heartbeat. The peak time difference (PTD) between the two resulting output signals in this radar can very well correlate with the PTT that was measured using electrocardiography (ECG) and photoplethysmography (PPG) sensors.