Two-Channel SAR-GMTI via Fractional Fourier Transform


  1. Chiu, S.
Corporate Authors
Defence R&D Canada - Ottawa, Ottawa ONT (CAN)
SAR along-track interferometry (SAR-ATI) can be used to measure motion in a scene by utilizing the phase and magnitude information of an interferogram. The phase of a target's interferogram phi-ATI is, to the first order, proportional to its slant range velocity nr at broadside. In this paper, a relatively unknown yet powerful technique, the so-called fractional Fourier transform (FrFT), is applied to the SAR-ATI in order to estimate moving target parameters. Due to the nature of SAR data collection, the moving target signal is unavoidably contaminated by the scene clutter. The FrFT technique is first used to improve the signal-to-clutter ratio (SCR) for an enhanced ATI phase estimation, which in turn allows the estimation of target's slant-range velocity. By mapping a target's signal onto a fractional Fourier axis, the FrFT permits a constant-velocity target to be fully focused in a fractional Fourier domain affording orders of magnitude improvement in SCR. Then moving target velocity and position parameters are derived and expressed in terms of an optimum fractional angle alpha and a measured fractional Fourier position up, allowing a target to be accurately repositioned and its velocity components computed. The proposed technique is applied to the data acquired by the two-aperture CV580 airborne system configured in its along-track mode. Results show that the proposed method is an effective and elegant way of accurately estimating moving target velocity and position parame

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Report Number
DRDC-OTTAWA-TM-2004-172 — Technical Memorandum
Date of publication
01 Oct 2004
Number of Pages

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