Monitoring Breathing Using a Doppler Radar

Correctional institutions are looking to adopt a non-obtrusive method for monitoring the vital signs of inmates in Canada. Doppler radar has been previously investigated as a potential method of vital signs detection and monitoring. This thesis presents an algorithm which uses the baseband output signal received by a Doppler radar to estimate the breathing rate from the detected motion associated with breathing. A reliability measure is provided with breathing rate estimates through the analysis of various signal quality indices. Results demonstrate that the algorithm is able to estimate the subject’s breathing rate (with high reliability) when the subject is motionless and breathing normally (mean error of 6 breaths per minute). The algorithm cannot accurately estimate the breathing rate when the subject is moving or holding their breath (mean error of 21 breaths per minute). During breath holds, it was found that the algorithm can likely estimate the subject’s heart rate.