24 September 1997 Methodology for ISAR autofocus using highly resolved subimages derived from the Wigner-Ville distribution
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This paper presents an application of the WVD (Wigner-Ville Distribution) to the problem of focusing an inverse SAR (ISAR) image over an extended period T of the order of two seconds or more. Over short subintervals or segments of duration (Delta) T covering the interval T, subimages may be formed via the normal weighted FFT applied to aligned complex range profiles. These subimages are of low resolution 1/(Delta) T, and though normally in focus, they are of limited use in estimating the parameters governing defocus over the longer interval T. A method is presented here whence subimages may be derived from a Wigner-Ville analysis, which have a resolution of the order of 1/T. This involves no paradox, since coherent data is assumed to be collected over the full duration T. Since the high resolution Wigner subimages contain detailed structures on the more stable scattering centers on the target, a simple correlation analysis can determine defocus parameters with much better accuracy than with conventional subimages, hence a focused image on the entire interval may be determined if desired. However for many purposes the stacked WVD subimages will by themselves provide sufficient information for target identification purposes.
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Peter N. R. Stoyle, Peter N. R. Stoyle, } "Methodology for ISAR autofocus using highly resolved subimages derived from the Wigner-Ville distribution", Proc. SPIE 3161, Radar Processing, Technology, and Applications II, (24 September 1997); doi: 10.1117/12.279481; https://doi.org/10.1117/12.279481


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