Effects of using superresolution techniques in ISAR imagery

Resolution in inverse synthetic aperture radar (ISAR) imagery is limited by the bandwidth of the transmitted signal and the total aspect change. Alternative spectral analysis techniques have been used in ISAR imaging in order to alleviate the loss of resolution. These superresolution techniques have been tested in radar data that has been previously interpolated from a polar format to Cartesian coordinates so that rotational motion is not a factor to consider. However, it is known that when a target rotates only a few degrees, the point scatterers that form the image do not migrate considerably and appear focused, thus the motion compensation step in the formation of a radar image can be avoided. Superresolution techniques are applied to the case when no prior interpolation is done. It is shown that superresolution techniques applied to polar reformatted data yields satisfactory results regardless of the total aspect change experienced by a target and the resolution improvement factor is only bounded by the factor of the specific method used.