2019_programme: THE INFLUENCE OF UPWELLING IN UNDERWATER COMMUNICATION OFF CABO FRIO ISLAND



  • Session: 05. Underwater Communications and Networking
    Organiser(s): Tsimenidis Charalampos, Mitchell Paul, Pelekanakis konstantinos
  • Lecture: THE INFLUENCE OF UPWELLING IN UNDERWATER COMMUNICATION OFF CABO FRIO ISLAND [invited]
    Paper ID: 890
    Author(s): P. Maia Lussac, C. Xavier Fábio, Osowsky Jefferson, P.Vio Renato, M. Jesus Sérgio
    Presenter: M. Jesus Sérgio
    Presentation type: oral
    Abstract: This work aims at understanding the influence of upwelling in underwater acoustic communications as observed in a shallow water environment on the coast of Cabo Frio Island, Rio de Janeiro, Brazil, during the BIOCOM'19 experiment in January 14-18, 2019. This sea trial is part of the project “Building of signalling with bioacoustic noise characteristics for underwater communications” (BIOCOM) whose objective is to characterise biological acoustic signals and, based on such information, to transmit communication signals compatible with the characteristics of the studied bioacoustic signals.\nThe scope of the experiment is to perform frequency modulated transmissions during 4 days from a source at 2.6m depth to a 4-hydrophones tetrahedron-like receiver array, located 1600m away in a range-dependent transect with depth between 3 and 22m. The deeper part of this transect is subject to sudden water column temperature change due to upwelling, therefore the study of its effect on communication performance is of interest for eventual adaptation and improvement. The project goal is to develop signalling technique that use the biological information of the soundscape to then establish communications with low signal to noise ratio in this environment, in an attempt of hiding, at some degree, the message in the noisy soundscape. A modulation scheme based on hyperbolic frequency swept chirps is used, aiming to increase detection capability at the receiver. The results indicate that upwelling can deteriorate the communications link due to the occurrence of severe refraction caused by the rise of cold water, that change significantly the water sound speed profile and potentially increase the number of bit errors. The present work indicates that the upwelling phenomenon significantly affects the acoustic channel and the underwater communication performance causing fluctuation of the signal level at the receiver. The development of techniques that efficiently compensate, or at least overcome the main effects of, the upwelling in shallow water acoustic propagation is still an open field of research.
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  • Corresponding author: Dr Prestes Maia Lussac
    Affiliation: Sea Studies Institute Admiral Paulo Moreira / University of Algarve
    Country: Brazil
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