Automatic target recognition in SAR using digitally-spotlighted phase history data

This paper is concerned with a representation of a target's complex Synthetic Aperture Radar signature that could be used for classification purposes. In this representation, the complex SAR signature of a desired target area (chip) as a function of the radar frequency and aspect angle (ω, φ) (i.e., the target area phase history data) are shown to directly map into the two-dimensional spectrum of the target's image via a nonlinear transformation; the same information base in the (ω, φ) domain is shown to be retrievable from the digitally-spotlighted complex SAR signature of the desired target region. For the classification problem (Automatic Target Recognition), the resultant complex SAR signature in the (ω, φ) domain is compared with a finite and discrete set of reference complex SAR signatures via a process that we refer to as signal subspace matched filtering.