Quai-Passive 5.8 GHz Front-End Design and Implementation for Vital Signs Detection

Sammanfattning: This thesis investigates the possibility to measure vital signs, such as heartbeat and respiratory rate, by developing a RF-front end for wireless detection. The RF-front has been developed and manufactured as a continuous wave Doppler radar receiver, which utilizes quadrature demodulation by means of a multi-port correlator together with power detectors for down conversion. This thesis has been part of an ongoing research project at Link¨opings University, to develop a sensor platform for wireless vital signs detection. This sensor platform has been broken down into two major parts, a radar RF front-end system and a back-end digital signal processing system. The back-end system consist of data acquisition- and a processing-part. It was shown that very low-frequency signals emulating vital signs can be detected, when direct frequency conversion and demodulation are performed with the multi-port detector. Due to the limitations of the instruments, 10-Hz signals were demonstrated.