Factorized Geometrical Autofocus: On the geometry search
Paper in proceedings, 2016

This paper deals with local geometry optimization within the scope of Factorized Geometrical Autofocus (FGA). The FGA algorithm is a Fast Factorized Back-Projection (FFBP) formulation with six free geometry parameters. These are tuned until a sharp image is obtained, i.e. with respect to an object function. To optimize the geometry (from a focus perspective) for a small image area, we propose an efficient routine based on correlation, sensitivity analysis and Broyden-Fletcher-Goldfarb-Shanno (BFGS) minimization. The new routine is evaluated using simulated Ultra-WideBand (UWB) data. By applying the FGA algorithm step-by-step, an erroneous geometry is compensated. This gives a focused image. In regard to run time, the new routine is approximately 100 times faster than a brute-force approach, i.e. for this FGA problem. For a general problem, the run time reduction will be far greater. To be more specific: with x parameters and N values to assess for each parameter; it is anticipated that the computational effort will decrease exponentially by a factor close to N-x.

Telecommunications

FGA

Electrical & Electronic

Back-Projection

SAR

Engineering

UWB

Autofocus

SAR

Author

Jan Torgrimsson

Chalmers, Earth and Space Sciences, Radar Remote Sensing

Lars Ulander

Chalmers, Earth and Space Sciences, Radar Remote Sensing

P. Dammert

H. Hellsten

IEEE Radar Conference (RadarConf), Philadelphia, PA, USA, May 02-06, 2016

1097-5764 (ISSN)

293-297

Areas of Advance

Information and Communication Technology

Subject Categories

Signal Processing

ISBN

978-1-5090-0863-6