1. A method for determining an estimated spatial correlation matrix {circumflex over (Q)} and an estimated temporal correlation matrix Â for a parametric adaptive matched filter to detect a target in a radar signal using space-time adaptive processing, wherein a spatial correlation matrices A and a temporal correlation matrix Q are known form training signals, comprising the steps of: determining a generalized likelihood ratio test (GLRT) T = max α p 1 ( x 0 ; α , A , Q ) p 0 ( x 0 ; A , Q ) , where {pi} i=0 1 are likelihood functions under a first hypothesis H 0 that the target is present and a second hypothesis H 1 that the target is not present in the radar signal, α is an unknown complex-values amplitude of the radar signal, x 0 is test signal, and max is a function that evaluates to a maximum; and determining a maximum likelihood (ML) of the spatial correlation matrix Q as {circumflex over (Q)} and the temporal correlation matrix A as Â subject to a persymmetric constraint; and replacing the spatial correlation matrices A and the temporal correlation matrix Q in the GLRT with {circumflex over (Q)} and Â, respectively.