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Frequency-dependent underwater acoustic communications performance using a pressure-gradient vector sensor

F. Bozzi(1), F. Zabel(2) and S.M. Jesus(1)
(1) LARSyS, University of Algarve, 8005-139 Faro, Portugal
(2) Marsensing Lda. Centro Empresarial Pav.A5, Campus de Gambelas, 8005-139 Faro, Portugal

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

Abstract:
Frequency-dependent directional gain of pressure-gradient vector sensors can be theoretically estimated, whereas its impact on the underwater acoustic communications performance may not be directly predicted. This study investigates how multichannel receiver structures may explore the frequency-dependent filtering capability of vector sensor directional channels, showing the frequency relation to communication performance. Vector sensor channel correlation and beam response are quantified using both analytical expressions and data from a shallow-water field experiment. In this experiment, a horizontal two-dimension single vector sensor is attached to a tripod at the sea bottom and receives coded coherent signals from a ship suspended sound source in two frequency bands: 4 to 6 kHz and 9 to 11 kHz. Results for several transmitter-receiver ranges and directions show a larger beam response peak to side lobe ratio for the higher frequency band. This expected behaviour reflects a better ambiguity mitigation, reducing the bit error rate. Vector sensor channels' cross-correlations show distinct values, depending on frequency bands, suggesting that frequency may be a determinant parameter in the used vector sensor channel combining approach.