An autofocus technique for video-SAR

Robert Linnehan; John Miller; Edward Bishop; Volker Horndt

doi:10.1117/12.2016430

23 May 2013 An autofocus technique for video-SAR

Robert Linnehan, John Miller, Edward Bishop, Volker Horndt

Proceedings Volume 8746, Algorithms for Synthetic Aperture Radar Imagery XX; 874608 (2013) https://doi.org/10.1117/12.2016430
Event: SPIE Defense, Security, and Sensing, 2013, Baltimore, Maryland, United States

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.

Citation Download Citation

Robert Linnehan, John Miller, Edward Bishop, and Volker Horndt "An autofocus technique for video-SAR", Proc. SPIE 8746, Algorithms for Synthetic Aperture Radar Imagery XX, 874608 (23 May 2013); https://doi.org/10.1117/12.2016430

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