Detection of space-time signal with scattering from background of isotropic noise field

Detection of a space time signal, scattered in space, in time, and in frequency is considered. The transmission channel is assumed to be linear and to have finite bandwidths L and F, where L is the dimension of the antenna aperture, F is the bandwidth of the radio section. The signal is considered to be narrow-band (F/f (sub o) = to or 1, f (sub o) is the carrier frequency), the antenna aperture is large (L/lambda (sub o) = to or 1, lambda (sub o) is the length of the wave of the carrier oscillations). An invariant principle of detection is obtained which ensures steady detection conditions in the case of a priori uncertainty with respect to the channel and the level of the noise field.