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An Efficient Solution to the Factorized Geometrical Autofocus Problem

Jan Torgrimsson (Institutionen för rymd- och geovetenskap, Radarfjärranalys) ; Patrik Dammert ; Hans Hellsten ; Lars M. H. Ulander (Institutionen för rymd- och geovetenskap, Radarfjärranalys)
IEEE Transactions on Geoscience and Remote Sensing (0196-2892). Vol. 54 (2016), 8, p. 4732-4748.
[Artikel, refereegranskad vetenskaplig]

This paper describes a new search strategy within the scope of factorized geometrical autofocus (FGA) and synthetic-aperture-radar processing. The FGA algorithm is a fast factorized back-projection formulation with six adjustable geometry parameters. By tuning the flight track step by step and maximizing focus quality by means of an object function, a sharp image is formed. We propose an efficient two-stage approach for the geometrical variation. The first stage is a low-order (few parameters) parallel search procedure involving small image areas. The second stage then combines the local hypotheses into one global autofocus solution, without the use of images. This method has been applied successfully on ultrawideband CARABAS II data. Errors due to a constant acceleration are superposed on the measured track prior to processing, giving a 6-D autofocus problem. Image results, including resolution, peak-to-sidelobe ratio and magnitude values for point-like targets, finally confirm the validity of the strategy. The results also verify the prediction that there are several satisfying autofocus solutions for the same radar data.

Nyckelord: Autofocus, back-projection, Synthetic aperture radar (SAR)

Denna post skapades 2016-07-04. Senast ändrad 2017-01-05.
CPL Pubid: 238887


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Institutioner (Chalmers)

Institutionen för rymd- och geovetenskap, Radarfjärranalys (2010-2017)



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