Subspace target detector for polarimetric synthetic aperture radar data

In this dissertation two new polarimetric subspace target detectors are developed based on a dihedral signal model for bright peaks within the target signature. The first is a coherent dihedral target detector based on the exact Huynen model for a dihedral. The second is a noncoherent dihedral target detector based on the Huynen model with an extra unknown phase term. Expressions for these polarimetric subspace target detectors are developed for both additive Gaussian clutter and more general additive spherically invariant random vector (SIRV) clutter including the K-distribution. For the case of Gaussian clutter with unknown clutter parameters, constant false alarm rate (CFAR) implementations of these polarimetric subspace target detectors are developed.; These new polarimetric subspace target detectors are related to a very general target detector developed by Kelly. The fully adaptive noncoherent dihedral target detector is a special case of Kelly's detector. These new detectors are related to the polarimetric whitening filter (PWF) target detector of Novak. When the number of unknown basis functions representing the noncoherent signal model spans the polarimetric space, the noncoherent target detector is equivalent to the PWF detector. These new detectors are also related to a polarimetric subspace target detector developed by Dilsavor and Moses. The Dilsavor-Moses detector was for a general Huynen scatterer, but did not have a closed form solution for the dihedral. Our detector has an explicit closed form solution for the Huynen dihedral.; The performance of these dihedral detectors is demonstrated with both simulated and real millimeter-wave fully polarimetric SAR data. The coherent dihedral detector, which is developed with a more accurate description of a dihedral, offers little performance advantage over the noncoherent dihedral detector, which is computationally more attractive. The dihedral detectors do a better job of separating tactical military targets from natural clutter compared to detectors that assume no knowledge about the target signal (i.e. the PWF detector). In one experiment using real fully polarimetric SAR data, we have shown that the dihedral detectors have about 27 false alarms per square kilometer passing all of the tactical targets, whereas the PWF detector has about 42 false alarms per square kilometer passing all of the tactical targets.