1. A method for detecting a target in a radar signal using space-time adaptive processing, comprising the steps: using an electronic processor for determining a test statistic T = max α ⁢ max λ ⁢ ∫ R ⁢ f 1 ⁡ ( x 0 , x 1 , … ⁢ , x K ❘ α , λ , R ) ⁢ p ⁡ ( R ) ⁢ ⁢ ⅆ R max λ ⁢ ∫ R ⁢ f 0 ⁡ ( x 0 , x 1 , … ⁢ , x K ❘ λ , R ) ⁢ p ⁡ ( R ) ⁢ ⁢ ⅆ R , where x 0 is a test signal, x k are K training signals, α is an unknown amplitude of a target signal within the test signal, λ is a scaling factor, R is a covariance matrix of the training signals, and a function max returns a maximum values; and comparing the test statistic to a threshold to determine whether the target is present, or not.