A Prototype Novel Zero-IF Non-Contact Respiration Monitor Using Software Defined Radio (SDR)

A Feasibility Study of Remote Non-Contact Vital Signs (NCVS) Monitoring in a Clinic Using a Novel Sensor Realized by Software-Defined Radio (SDR)

“…angle that the receive (RX) antenna can receive the reflected transmit (TX) signal from the monitored subject, and that there is sufficient distance separating the TX/RX antennas to reduce their interactions. The fundamental operational principle of our Doppler-based NCVS system has been described in [4][5][6][7] and above. Basically, our system transmits a 2.4 GHz continuous wave (CW) RF signal and then receives the reflected wave off the subject's chest wall.…”

“…can all be changed in this GUI. The fundamental operational principle of our Doppler-based NCVS system has been described in [4][5][6][7] and above. Basically, our system transmits a 2.4 GHz continuous wave (CW) RF signal and then receives the reflected wave off the subject's chest wall.…”

“…Thus, the system may suffer from huge 1/f noise if the received signal was directly downconverted to baseband [20]. Since this NCVS sensor system can produce rather accurate RR at 1 m and 1.5 m in our engineering lab, with average error rates of 0.64 and 0.26 BPM, respectively [6], in this work, we fix the test range at 1.3 m to optimize the system parameters setting. After performing experiments to optimize the system performance by adjusting various parameters in our engineering lab, the TX/RX gain and IF frequency were found to be optimal when set to 34/45 and 1 kHz at the system operating frequency of 2.4 GHz.…”

“…New variants of the virus, such as the delta variant, delta plus variant, lambda variant, omicron variant, etc., continue to pop up. To help protect healthcare workers (HCWs), remote monitoring of vital signs using various techniques such as visible light sensing [1], millimeter wave radar [2], UWB (ultra-wideband) radar sensor [3], phased-array and fixed beam CW (continuous-wave) radar sensors using custom hardware [4,5], and software-defined radio (SDR)-based radar sensor systems have all been reported [6][7][8][9][10][11]. Differently from traditional contact-based vital signs monitoring systems currently widely used in clinically practices, these remote or non-contact vital signs (NCVS) monitoring systems are targeted to monitor patients' vital signs remotely and continuously; therefore, if an NCVS sensor system can be proven to be robust enough for clinically use, it would offer some key advantages as follows: (1) the HCWs can avoid direct contact with people infected with COVID-19 during vital signs setup/adjustment/reading to reduce their infection risks; (2) the NCVS monitoring system can be used on people suspected to be or confirmed infected with COVID-19 to safely quarantine them at home or in a hotel for telemedicine practice and for wireless acute-care.…”

“…The UWB radar [3], on the other hand, directly measures the periodic distance change in chest movement to estimate the RR and HR. As for the SDR-based radar sensor systems, several studies have focused on the phase changing of the received signals [6][7][8][9], while one work also targeted the distance variation [10], and the other extracted the RR and HR by analyzing the change in both phase and magnitude of the received signal [11].…”