SAR Processing Without a Motion Measurement System
Artikel i vetenskaplig tidskrift, 2019

This paper leads a discussion on how to form a Synthetic Aperture Radar (SAR) image without knowing the relative track. That is, within the scope of factorized geometrical autofocus (FGA). The FGA algorithm is a base-2 fast factorized backprojection (FFBP) formulation with six free geometry parameters (per subaperture pair). These are tuned step by step until a sharp image is obtained. This innovative autofocus concept can compensate completely for an erroneous geometry. The FGA algorithm has been applied successfully on two ultrawideband (UWB) data sets, acquired by the CARABAS II system at very high frequency (VHF)-band. The relative tracks are known (measured accurately). We, however, adopt and modify a basic geometry model. A linear equidistant track at fixed altitude is initially assumed. Apart from deviations due to linearization, a similar to 2.5-m/s along-track velocity error is also introduced. Resulting FGA images are compared to reference images and verified to be focused. This indicates that it is feasible to form a wavelength-resolution SAR image at VHF-band without support from a motion measurement system. The execution time for the examples in this paper is about five times longer with autofocus than without. Hence, the FGA algorithm is now fit for use on a regular basis.

Synthetic Aperture Radar (SAR)

back-projection (BP)

factorized geometrical autofocus (FGA)

Autofocus

Författare

Jan Torgrimsson

Chalmers, Rymd-, geo- och miljövetenskap, Mikrovågs- och optisk fjärranalys

Patrik Dammert

Saab Surveillance

Hans Hellsten

Saab Surveillance

Lars Ulander

Chalmers, Rymd-, geo- och miljövetenskap, Mikrovågs- och optisk fjärranalys

IEEE Transactions on Geoscience and Remote Sensing

0196-2892 (ISSN)

Vol. 57 2 1025-1039

Ämneskategorier

Signalbehandling

Datorseende och robotik (autonoma system)

Medicinsk bildbehandling

DOI

10.1109/TGRS.2018.2864243

Mer information

Senast uppdaterat

2019-02-18