Optimum and Suboptimum Detection of Directional Gaussian Signals in an Isotropic Gaussian Noise Field Part I: Likelihood Ratio and Power Detectors

The detection of underwater signals is frequently accomplished by highly directional hydrophone arrays. This paper reviews some of the well-known optimum techniques that are used in processing signals of this type, and compares them to simpler suboptimum methods. It appears that the main effect of optimum detectors is to eliminate the low frequencies where there is substantial correlation between the noise components received by adjacent hydrophones. This effect is easily approximated by simple suboptimum receivers. The question of the detection of modulated noise signals is also considered, but it is concluded that if the background noise level is known precisely, knowledge of the modulation waveshape does not contribute very much to detectability.