Rotation and Vital Sign Sensor using Simple Microwave Transceiver

In this paper, a simple microwave transceiver architecture is proposed which can remotely sense target movement by using amplitude modulation/ demodulation principle. The proposed transceiver is used to detect the periodic rotational motion of pedestal fan blades, and the revolution per minute (RPM) can be correlated from the frequency response of the output of the transceiver block. Additionally, the proposed simple module is used to detect the vital sign (breathing and heartbeat) of a person under test. The transmitted signal from a source is modulated by the moving target and the target motion is detected by receiving the modulated signal and mixing it with the original signal to find out the frequency components which quantifies the rotational or translational object motion. The real time data acquisition is done by using a digital storage oscilloscope along with a PC system. The proposed module has maximum detectable operating range of about 70 cm for vital sign detection and about 120 cm for detecting the revolution of fan blades for an input signal level of 0 dBm. The proposed system works at 2.4 GHz frequency. The system can be applied for generalized translational and rotational motion detection applications.