A two stage beamforming approach for low complexity CFAR detection and localization for passive radar

We propose a two stage beamforming technique for localisation of moving target in a passive radar environment. In order to perform localization and tracking in Cartesian plane, in addition to detection in the range Doppler domain, it is necessary to have angle of arrival of target return, which is obtained using beamforming. The beamforming technique can also enhance signal to disturbance ratio. However, performing constant false alarm rate detection (CFAR) in this case requires storing beamformer output statistics for every range-Doppler-azimuth bin which significantly burdens the system and hinders the real time processing and tracking of moving targets. Using experimental measurements, we demonstrate real time detection and tracking of an airborne target using a two stage beamforming approach, where a smaller set of beams is used in the first stage for CFAR detection and a larger set of beams is used in the second stage for angle of arrival estimation with higher accuracy.