DocumentCode :
1756898
Title :
Semiparametric Statistical Stripmap Synthetic Aperture Autofocusing
Author :
Marston, Timothy M. ; Plotnick, Daniel S.
Author_Institution :
Panama City Div., Naval Surface Warfare Center, Panama City, FL, USA
Volume :
53
Issue :
4
fYear :
2015
fDate :
42095
Firstpage :
2086
Lastpage :
2095
Abstract :
Autofocusing synthetic aperture imagery by maximizing a statistical quality metric such as contrast or sharpness is a well-documented approach in both synthetic aperture radar (SAR) literature and synthetic aperture sonar literature. It is most successfully applied in spotlight-mode SAR applications, where the assumption of spatial invariance of the corrupting phase function is strong and expressions for the gradients of various quality metrics with respect to standard error models have been calculated. Examples of application to stripmap imagery often involve sectioning images into small blocks, allowing spotlight algorithms to be patchwise applied. This paper formulates the gradient of the cost function in a manner that is consistent with the stripmap error model, inherently providing solutions that compensate for the spatial variance while simultaneously bypassing the need for subdividing an image or aperture. This paper formulates the stripmap gradient expression in conjunction with a computationally efficient imaging approach to rapidly achieve metric-maximizing solutions. Demonstrations are shown on a widebeam wideband rail-based system experiencing random jitter and on an unmanned-underwater-vehicle-mounted sonar system exhibiting artificially injected crabbing and sway errors. Results indicate that the algorithm is particularly effective at compensating for random and rapidly oscillating navigation and jitter errors, as well as sidelobes introduced by crabbing in arrayed systems.
Keywords :
geophysical image processing; remote sensing by radar; synthetic aperture radar; synthetic aperture sonar; SAR literature; artificially injected crabbing error; artificially injected sway error; corrupting phase function; cost function gradient; metric-maximizing solutions; semiparametric statistical stripmap synthetic aperture autofocusing; spotlight-mode SAR applications; stripmap error model; stripmap gradient expression; stripmap imagery; synthetic aperture sonar literature; to statistical quality metric; unmanned-underwater-vehicle-mounted sonar system; widebeam wideband rail-based system; Apertures; Arrays; Computational modeling; Focusing; Measurement; Synthetic aperture sonar; Synthetic aperture sonar (SAS) radar autofocus stripmap;
fLanguage :
English
Journal_Title :
Geoscience and Remote Sensing, IEEE Transactions on
Publisher :
ieee
ISSN :
0196-2892
Type :
jour
DOI :
10.1109/TGRS.2014.2353515
Filename :
6913560
Link To Document :
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