Sensing respiratory rate by using an FM-CW radar in UHF band and a tailored AM technique

In order to detect human vital signs, as respiratory rate, Doppler radar could be used. However the oscillation frequency have to be in the SHF band or higher in order to have an appreciable Doppler frequency shift. In this paper, a FM-CW radar in UHF band is used to detect this signal by extracting the amplitude modulation of the reflected signal using an specific digital signal processing. Respiratory rates of 11 and 15 breath per minute have been measured for two different persons. These values are within the natural range of respiratory rate.