Non-Contact Respiration Rate Estimation using 24 GHz Pulse Radar Employing Envelope Detection

Recently, there are a lot of interest in utilizing radar technology to realize non-contact respiration rate (RR) measurements. This paper presents an RR estimation using a 24 GHz pulse radar employing an envelope detection on the IF signal at the receiver. Two methods of RR estimation methods were discussed: (1) a peak difference in the time domain, and (2) peak detection of the FFT spectrum of the receiving signal. The accuracy of the proposed method were investigated through from actual measurements of subjects breathing in front of the radar. Both methods were found to produce comparable accuracy RR estimation, however, using peak detection of the FFT spectrum marked slightly better accuracy. The measurement error was larger when using peak difference the time domain, due to measurement noises impacting the calculation of peak difference. The results of this paper indicated the workability of the proposed method, and hence developed a foundation of the non-contact RR estimation system to be implemented in various patient monitoring application with specific breathing conditions, such as acute breathing syndromes.