Modulation Transfer Function Analysis of Kelvin Wakes and Ambient Wave Images

摘要

Synthetic aperture radar (SAR) images collected during a 1989 surface ship wakeexperiment are analyzed using a linear imaging model which includes contributions due to velocity bunching, tilt modulation and hydrodynamic modulation as well as azimuth falloff and coherent speckle effects. This model adequately predicts the overall shape of the image spectrum for ambient waves as observed from three different look directions, although there are some discrepancies for range-traveling waves which are attributed to uncertainties in the tilt and hydrodynamic modulation. Inversion of the model to yield estimates of the Kelvin wake and ambient wave heights appears to be successful, although the results are sensitive to the value assumed for the surface decorrelation time.