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Proceedings Paper

An autofocus technique for video-SAR
Author(s): Robert Linnehan; John Miller; Edward Bishop; Volker Horndt
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Paper Abstract

General Atomics Aeronautical Systems, Inc. (GA-ASI) is designing a real-time, video-SAR (synthetic aperture radar) mode for a test bed radar system. Typically, the flight path for video-SAR is circular with the sensor directed inward and broadside relative to the platform heading, providing continuous surveillance over a region of interest. The SAR frames are processed using the backprojection algorithm onto a Cartesian coordinate system at the nominal ground level and oriented in a fixed direction. Standard autofocus techniques are ineffective since the azimuth dimension will be oblique through the images when the synthetic apertures are not centered at a multiple of π/ 2 along the flight path. We have developed an algorithm that estimates the phase gradient from pseudo point-scatterers, regardless of the platform position, and focuses the images before they are compiled into a SAR video. Thus the efficiency and utility of fixed frame video-SAR processing is retained, while image sharpness and quality are not compromised due to antenna motion error measurements and / or severe atmospheric effects during propagation.

Paper Details

Date Published: 23 May 2013
PDF: 10 pages
Proc. SPIE 8746, Algorithms for Synthetic Aperture Radar Imagery XX, 874608 (23 May 2013); doi: 10.1117/12.2016430
Show Author Affiliations
Robert Linnehan, General Atomics Aeronautical Systems Inc. (United States)
John Miller, General Atomics Aeronautical Systems Inc. (United States)
Edward Bishop, General Atomics Aeronautical Systems Inc. (United States)
Volker Horndt, General Atomics Aeronautical Systems Inc. (United States)


Published in SPIE Proceedings Vol. 8746:
Algorithms for Synthetic Aperture Radar Imagery XX
Edmund Zelnio; Frederick D. Garber, Editor(s)

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