Modified Phase Gradient Algorithm for ISAR Image Autofocus with Large Apertures
Konferenz: EUSAR 2018 - 12th European Conference on Synthetic Aperture Radar
04.06.2018 - 07.06.2018 in Aachen, Germany
Tagungsband: EUSAR 2018
Seiten: 6Sprache: EnglischTyp: PDFPersönliche VDE-Mitglieder erhalten auf diesen Artikel 10% Rabatt
Rosebrock, Jens; Dapice, Giovanni; Sommer, Svenja; Cerutti-Maori, Delphine (Fraunhofer Institute for High Frequency Physics and Radar Techniques, Germany)
Autofocus plays a major role in synthetic aperture radar (SAR) and inverse SAR (ISAR) processing to obtain wellfocused radar images from the pulse data acquired by imaging radars. The simplest autofocus algorithm tracks a prominent (or dominant) scatterer and takes its phase as reference. If there are multiple scatterers with comparable amplitudes or if a dominant scatterer is not visible in the whole coherent processing interval (CPI), this algorithm often fails. The phase gradient algorithm (PGA) overcomes this situation by using multiple scatterers. In its original form it assumes that phase errors cause streaks in cross-range direction in the reconstructed image by one-dimensional convolution. This assumption is, however, only valid for short apertures. In this paper a modification of the PGA is proposed which works even for large apertures.