Non-Contact Measurement of Human Respiration and Heartbeat Using W-band Doppler Radar Sensor

Abstract

This paper presents a W-band continuous-wave (CW) Doppler radar sensor for non-contact measurement of human respiration and heartbeat. The very short wavelength of the W-band signal allows a high-precision detection of the displacement of the chest surface by the heartbeat as well as respiration. The CW signal at 94 GHz is transmitted through a high-gain horn antenna to the human chest at a distance of 1 m. The phase-modulated reflection signal is down-converted to the baseband by the quadrature mixer with an excellent amplitude and phase matches between I and Q channels, which makes the IQ mismatch correction in the digital domain unnecessary. The baseband I and Q data are digitized using data acquisition (DAQ) board. The arctangent demodulation with automatic phase unwrapping is applied to the low-pass filtered I and Q data to effectively solve the null point problem. A slow-varying DC component is rejected in the demodulated signal by the trend removal algorithm. Then, the respiration signal with a frequency of 0.27 Hz and a displacement of ~6.1 mm is retrieved by applying a low-pass filter. Finally, the respiration signal is removed by the band-pass filter and the heartbeat signal is extracted, showing a frequency of 1.35 Hz and a displacement of ~0.26 mm. The extracted respiration and heartbeat rates are very close to the manual measurement results. The demonstrated W-band CW radar sensors can be easily applied to find the angular location of the human body by using a phased array under a compact size.

Advancements in Methods and Camera-Based Sensors for the Quantification of Respiration

“…The characterization of chest wall motion has been addressed in many methodological works, which presented interesting results, including for the general (e.g., motion quantification) and specific levels (e.g., illness detection/severity assessment and scoring). This can be grouped as follows: [ 57 , 61 , 62 , 64 , 68 , 72 , 117 , 120 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 , 136 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 147 , 148 , 149 ] (2010–2015), [ 3 , 10 , 47 , 48 , 49 , 53 , 54 , 95 , 97 , 99 , 101 , 105 , 111 , 122 , 150 , 151 , 152 , 153 , 154 , 155 , 156 , 157 , 158 ...…”

“…In the last few years, a variety of radar-based sensors has been investigated for respiration monitoring [ 44 , 51 , 69 , 82 , 94 , 95 , 96 , 97 ]. In 2019, Nosrati et al [ 94 ] proposed a phased array approach with a multiple-input multiple-output (MIMO) beamforming design.…”

Performance Evaluation of Vibrational Measurements through mmWave Automotive Radars

“…Moreover, this technique allows for a high sampling rate, that makes it possible to analyze a wide spectrum of vibrational frequencies, thus making Radar devices even more versatile. Comparing, for example, the results of [36] with [37], it is possible to assert that using a higher frequency makes it possible to detect smaller vibrations. This is possible also with a lower frequency, but the system will be more complex and more expensive.…”

Car2Car Communication Using a Modulated Backscatter and Automotive FMCW Radar

“…In recent years, microwave and mm-wave radars have been increasingly used in automotive, industrial and communications applications. The availability of low-cost millimeter band radars has allowed the emergence of new applications such as contactless and unobtrusive vital sign measurement with a millimeter-wave radar system [ 16 , 17 , 18 , 19 ]. In these applications, small phase changes due to micro-Doppler chest movements are used to extract the breathing and heart rate from Doppler or FMCW radars.…”