Factorized Geometrical Autofocus for UWB UHF-band SAR with a GPS-supported Linear Track Model
Artikel i vetenskaplig tidskrift, 2022

This paper describes how to form a SAR image without proper motion quantities. That is within the scope of factorized geometrical autofocus (FGA). The FGA algorithm is a fast-factorized back-projection formulation with adjustable geometry parameters. Sub-apertures are tuned and merged pair by-pair (base-2) and step-by-step. With this technique, we can correct an erroneous geometry and form a focused image. The FGA algorithm has been applied on two data sets, acquired by the UWB CARABAS 3 system at UHF-band. The tracks are measured accurately by means of a DGPS. We however adopt and modify a geometry model. Equidistant linear tracks at fixed altitudes are assumed. These tracks are then regulated via a two-stage search strategy and a reverse processing procedure. As this is a first experiment at UHF-band, we provide GPS-based length values for the sub-apertures, to simplify the search. Multiple geometry solutions are tested for each sub-aperture pair, i.e. at each resolution level. Resulting FGA images are compared to reference images and verified to be focused. This indicates that it is feasible to form a focused image with wavelength resolution at UHF-band, i.e. with minimum support from a motion measurement system.

Electronics packaging

SAR

FGA

Apertures

back-projection

Global Positioning System

Image resolution

Geometry

Azimuth

Autofocus

Tracking

Författare

Jan Torgrimsson

Mikrovågs- och optisk fjärranalys

Patrik Dammert

Saab

H. Hellsten

Saab

Lars Ulander

Totalförsvarets forskningsinstitut (FOI)

IEEE Transactions on Aerospace and Electronic Systems

0018-9251 (ISSN)

Vol. In Press

Ämneskategorier

Signalbehandling

Datorseende och robotik (autonoma system)

Medicinsk bildbehandling

DOI

10.1109/TAES.2022.3149235

Mer information

Senast uppdaterat

2022-03-14