Investigation of and improvements to a continuous wave radar system for human detection through walls
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A low cost CW radar system with a two element receiving array has been under development for detecting indoor movers using the Doppler and direction of arrival information of the targets. This thesis investigates some research issues and possible improvements to the radar system to improve its operation. First when the CW radar is used in a through wall paradigm it is important to study the channel propagation effects through the complex medium of a wall. Hence narrowband and wideband measurements were conducted to understand some of the wall phenomenolgy such as attenuation and polarization dependence of different walls. The second issue investigated is the jamming of the receiver by the strong coupling from the transmitter that prevents the detection of the weak returns from the target. A circularly polarized microstrip array was designed at 2.4 GHz to reduce this coupling in the bistatic configuration of the CW radar. Third, the Doppler tracks of the different targets contain additional microdopplers due to the arm and leg motion. This makes the simultaneous tracking of multiple targets very difficult. Hence data association algorithms based on Nearest Neighbour Standard Filtering (NNSF) and Probabilistic Data Association (PDAF) algorithms using Kalman Filtering were developed to track the Doppler tracks of multiple targets in the presence of the microdoppler features.