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A vector sensor for low SNR communications: a channel geometry study

F. Louza and S.M. Jesus
LARSyS, University of Algarve, 8005-139 Faro, Portugal

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Ref.: Int. Conf. on Acoustics (ICA), Gyeongju (South Korea), October 2022

Research on low SNR communications has been encouraged for autonomous underwater vehicles (AUV) covert communications while contributing to reducing the environmental noise level. In shallow water, most communication systems rely on spatial diversity, requiring arrays of pressure sensors to deal with multipath and to increase the SNR through multichannel combining. However, these multiple sensors arrangements are not suitable for AUVs. Compact in size, acoustic vector sensors (VS) measure both acoustic pressure and particle velocities, also providing diversity gain. But literature about VS for communications is still limited. Thus, this paper presents a study on the VS multichannel combining for low SNR communications in shallow water. As part of the multidisciplinary EMSO-PT project, an experiment took place off the coast of Algarve (Portugal) on Nov 24th,2021. A single 2-D vector sensor mounted on a tripod was posed on the bottom. An omnidirectional source suspended from a vessel transmitted broadband signals from several positions, varying both the source-receiver range and the bathymetry profile. Recorded impulsive noise was added to the signals to reduce SNR. Coherent communication performance was evaluated for two distinct time-varying channel geometries. Preliminary results show that vector sensor multichannel combining may provide an average MSE gain of up to 3.8 dB compared to the pressure channel.