In this paper we formalize a theory for indicators designed to focus ISAR imagery of non-cooperative targets. These indicators represent variations of the Fisher information and entropy measures, and are capable of operating either in the spatial-frequency domain or in the spatial domain. This freedom of choice is advantageous since the information on the target's representation in either domain has phase and magnitude components, which can be efficiently exploited to resolve and focus the target's primary elements. These elements are displayed as radar cross section (RCS) distribution, we propose a phase correction algorithm based on parametric models of a target's temporal maneuvers. The approach is to quantify the phase non-linearities via the Fisher information or entropy measure that is dependent on motion parameter estimates. The optimization of these parameter estimates is a m-dimensional search problem that minimizes the focus quality indicator over a prescribed tolerance for a given SNR. The coordinates of this minimum point are subsequently used to generate a phase correction factor that eliminates image blurring, thus providing better focusing for effective target recognition.

Date Published: 10 June 1996
PDF: 12 pages
Proc. SPIE 2757, Algorithms for Synthetic Aperture Radar Imagery III, (10 June 1996); doi: 10.1117/12.242024

Published in SPIE Proceedings Vol. 2757:
Algorithms for Synthetic Aperture Radar Imagery III
Edmund G. Zelnio; Robert J. Douglass, Editor(s)