| Microwave Doppler radar can be used for remote monitoring of physiological motion for humans or animals, but suffers from limitations in selectivity, clutter rejection, subject isolation and identification. The research presented in this dissertation proposes a solution to this problem by placing passive radio frequency tags on the subject of interest and designing radar systems to detect backscattered information from the tags. Two types of passive radio frequency tags and radar systems were developed and tested successfully to independently track and monitor moving sources that have tag as well as sources that do not have a tag, when both the motions were occurring in front of the radar system. The contributions of this dissertation encompass innovative solutions in software and hardware including theory, simulation and design of Doppler radar compatible tags, design, implementation and analysis of radar receivers, and innovative use of signal processing techniques to extract more useful information from the radar and extend its application. The use of suggested approaches has created a Doppler radar system that would improve detection rate by as much as 100% as compared to a regular quadrature Doppler radar. In addition to tracking motion of one or more tagged objects in presence of untagged motion (clutter), the system can reliably provide information about the clutter. The designed radar systems are shown to provide the required selectivity, subject isolation, identification and multiple subject detection that brings Doppler radar one step closer to its commercial feasibility for a wide range of applications that include remote health monitoring, activity monitoring and search and rescue operations. |
