24 Jan 2013 adminFrumam – G. Gassier (IM2NP) : Subspaces methods in passive radarCarte non disponible Date/heure Date(s) - 24/01/201314 h 00 min - 15 h 00 min Catégories Pas de Catégories Subspaces methods in passive radar. By Ghislain Gassier, IM2NP. A bistatic passive Doppler radar system exploits already existing RF transmitters (illuminators of opportunity) to detect and localize moving targets. Our interest is focused on Digital Video Broadcasting-Terrestrial (DVB-T) signals which exhibit a wide bandwidth, providing an interest- ing resolution in terms of bistatic range. In passive radar, the main difficulty is to extract the moving target weak reflections masked by the direct path signal and echoes from static reflec- tors (background clutter) in the radar ambiguity diagram. In this study, we propose a new efficient method to filter both the di- rect path signal and the static clutter while preserving echoes from even slow-moving targets. Our method fully exploits the typical structure of DVB-T signals (Orthogonal Frequency Division Multiplexing modulation, with pilots carriers and cyclic prefix) allowing easy estimation of the frequency response of the propagation channel. Noting that, over a relatively large observation time, the frequency response of the propagation channel due to the unwanted signals (resp. to the Doppler echoes) is stationary (resp. unstationary and zero-mean), one can estimate the channel response due to the unwanted signals through time-averaging over multiple shorter time-blocks. From this channel response estimation, the direct path signal and the clutter signal are then synthesized and removed from the received signal. Simulation and experimental results validate the proposed method. At the end, I will expose a prospective approach based on sparse repre- sentation of autocorrelation RADAR signals.