Electric detection of divers in harbor environments

Abstract

In this paper we compare the detection performance of underwater electric-field sensors against divers using three different detection algorithms (matched filter, non-coherent and quadrature detectors). The detection performance is quantified and presented as ROC-curves. The empirical results are based on measurements of signatures from divers with open circuit breathing systems. They were performed during two sea-trials in diverse environments. One site is a remote area with relatively low anthropogenic activity and the other site is a busy container terminal in the port of Gothenburg, both sites in Sweden. Of the three detectors evaluated, no single detector stands out. This may imply the usefulness of fusion as a means of improving the performance in the future. In Gothenburg harbor detection of divers can be performed at signal-to-noise ratios from −20 to 0 dB, depending on the noise situation. In addition to detection, it is found that it is possible to classify a contact as a diver.