Maximum-likelihood estimation of focus of Gaussian signals (Corresp.)

The problem of optimally processing data with unknown focus is investigated by the method of maximum likelihood. It is assumed that the signal prior to defocusing is a zero-mean Gaussian process with a known spectral density and a very short correlation interval relative to the observation interval, and that it is received (recorded) with additive, white Gaussian noise. One of the most interesting data systems that satisfy the assumptions and approximations made is side-looking, synthetic-aperture radar. An electro-optical system that computes the maximum-likelihood estimate is shown, and the modifications to estimate also the signal sample function are discussed.