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Lookup NU author(s): Professor Jeffrey Neasham
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High-rate acoustic communication experiments were conducted in a dynamic estuarine environment. Two current profilers deployed in a shipping lane were interfaced with acoustic modems, which modulated and transmitted the sensor readings every 200 s over a period of four days. QPSK modulation was employed at a raw data rate of 8 kbits on a 12-kHz carrier. Two 16-element hydrophone arrays, one horizontal and one vertical, were deployed near the shore. A multichannel decision-feedback equalizer was used to demodulate the modem signals received on both arrays. Long-term statistical analysis reveals the effects of the tidal cycle, subsea unit location, attenuation by the wake of passing vessels, and high levels of ship-generated noise on the fidelity of the communication links. The use of receiver arrays enables vast improvement in the overall reliability of data delivery compared with a single-receiver system, with performance depending strongly on array orientation. The vertical array offers the best performance overall, although the horizontal array proves more robust against shipping noise. Spatial coherence estimates, variation of array aperture, and inspection of array angular responses point to adaptive beamforming and coherent combining as the chief mechanisms of array gain. © 2007 Acoustical Society of America.
Author(s): Van Walree PA, Neasham JA, Schrijver MC
Publication type: Article
Publication status: Published
Journal: Journal of the Acoustical Society of America
Year: 2007
Volume: 122
Issue: 6
Pages: 3495-3506
Print publication date: 01/01/2007
ISSN (print): 0001-4966
ISSN (electronic): 1460-2210
Publisher: Acoustical Society of America
URL: http://dx.doi.org/10.1121/1.2793706
DOI: 10.1121/1.2793706
PubMed id: 18247758
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