MCA: a multichannel approach to SAR autofocus

  • Authors:

  • Robert L. Morrison;Minh N. Do;David C. Munson

  • Affiliations:

  • Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA and Department of Electrical and Computer Engineering and Coordinated Science Laboratory, University of Illinois at Urbana- ...;Coordinated Science Laboratory, Department of Electrical and Computer Engineering and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL;Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI

  • Venue:
  • IEEE Transactions on Image Processing
  • Year:
  • 2009

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Abstract

We present a new noniterative approach to synthetic aperture radar (SAR) autofocus, termed the multichannel autofocus (MCA) algorithm. The key in the approach is to exploit the multichannel redundancy of the defocusing operation to create a linear subspace, where the unknown perfectly focused image resides, expressed in terms of a known basis formed from the given defocused image. A unique solution for the perfectly focused image is then directly determined through a linear algebraic formulation by invoking an additional image support condition. The MCA approach is found to be computationally efficient and robust and does not require prior assumptions about the SAR scene used in existing methods. In addition, the vector-space formulation of MCA allows sharpness metric optimization to be easily incorporated within the restoration framework as a regularization term. We present experimental results characterizing the performance of MCA in comparison with conventional autofocus methods and discuss the practical implementation of the technique.