Real-Time Non-Contact Millimeter Wave Radar-Based Vital Sign Detection

Abstract

In this paper, the extraction of the life activity spectrum based on the millimeter (mm) wave radar is designed to realize the detection of target objects and the threshold trigger module. The maximum likelihood estimation method is selected to complete the design of the average early warning probability trigger function. The threshold trigger module is designed for the echo signal of static objects in the echo signal. It will interfere with the extraction of Doppler frequency shift results. The moving target detection method is selected, and the filter is designed. The static clutter interference is filtered without affecting the phase difference between the detection sequences, and the highlight target signal is improved. The frequency and displacement of thoracic movement are used as the detection data. Through the Fourier transform calculation of the sequence, the spectrum value is extracted within the estimated range of the heartbeat and respiration spectrum, and the heartbeat and respiration signals are picked up. The proposed design uses Modelsim and Quartus for CO-simulation to complete the simulation verification of the function, extract the number of logical units occupied by computing resources, and verify the algorithm with the vital signs experiment. The heartbeat and respiration were detected using the sports bracelet; the relative errors of heartbeat detection were 0–6.3%, the respiration detection was 0–9.5%, and the relative errors of heartbeat detection were overwhelmingly less than 5%.

Systematic Literature Review Regarding Heart Rate and Respiratory Rate Measurement by Means of Radar Technology

“…In five experiments, the test persons were measured through a mattress in a lying position [28,77,105,106,114], and in one study, they were measured through a chair in a sitting position [54]. In ten studies, it was not possible to obtain any information on the positioning of the test persons [12,18,30,35,41,43,64,67,95,108].…”

“…Multiple specifications of the positioning were possible due to the use of several radars, among other things. Four studies did not contain any information on the relative position of the radar [41,43,64,67].…”

“…The frequency most frequently selected was 24 GHz. It was used in 29 studies [2,3,12,14,17,18,21,23,28,33,36,40,42,44,62,64,66,70,71,82,84,96,98,[100][101][102]105,106,120]. In 16 studies, several radar frequencies or a frequency spectrum were used [2,5,10,12,32,33,39,51,53,71,75,87,92,104,105,108].…”

Contactless metabolism estimation of small animals using high-frequency millimeter-wave radar

“…The unique ability of mm-waves to penetrate clothing and body hair allows radar signals to capture movements associated with heat transfer and lung ventilation. This makes radar technology one of the most valuable methods for monitoring RR, HR, and muscle movements in a contactless manner [19][20][21][22][23] . While several technologies mentioned above can effectively extract vital sign signals, such as RR and HR, no studies have successfully estimated metabolic rates like VO2.…”

Incorporation of Digital Modulation into Vital Sign Detection and Gesture Recognition Using Multimode Radar Systems

“…Of these methods, the most prominent approach that has emerged is the modulation of the carrier frequency of the radar, which allows for the range and speed of a target to be recovered. Frequency-modulated continuous wave (FMCW) radar systems are used predominantly in the automotive industry [ 3 ] and are still being explored for use in activity monitoring [ 4 , 5 , 6 ], gesture recognition [ 7 , 8 , 9 ], and vital sign detection [ 10 , 11 , 12 , 13 ]. In addition, improvements are still being made to CW Doppler systems used to perform vital sign monitoring and gesture detection through the in-depth analysis of processing methods [ 14 ] and gesture frame detection [ 15 ].…”