The role of spectrum estimation in forming high-resolution radar images

A novel approach is developed for forming high-resolution images of radar targets from delay Doppler spotlight-mode radar data. This approach is based on a model for the target´s reflectivity in terms of wide-sense stationary, uncorrelated scatterers having complex-valued Gaussian statistics. The imaging problem is to estimate the target´s scattering function in terms of radar-echo data acquired with a series of target illuminations. A method is developed for solving this multidimensional spectrum estimation problem through the use of maximum-likelihood estimation implemented using the expectation-maximization algorithm