Effects of tidally driven temperature fluctuations on shallow-water acoustic communications at 18 kHz

Carbone, Nicholas M.; Hodgkiss, William S.

doi:10.1109/48.820739

Cited by 42 publications

(19 citation statements)

References 18 publications

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“…[16][17][18] For example, the effects of tidally driven temperature fluctuations on underwater coherent acoustic communications have been studied at a carrier frequency of 18 kHz. 16 However, the relationship between environmental fluctuations and the performance of coherent underwater acoustic communications is not fully understood yet.…”

Section: Introductionmentioning

confidence: 99%

Impact of ocean variability on coherent underwater acoustic communications during the Kauai experiment (KauaiEx)

Song

Badiey²,

Song³

et al. 2008

The Journal of the Acoustical Society of America

106

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During the July 2003 acoustic communications experiment conducted in 100 m deep water off the western side of Kauai, Hawaii, a 10 s binary phase shift keying signal with a symbol rate of 4 kilosymbol/s was transmitted every 30 min for 27 h from a bottom moored source at 12 kHz center frequency to a 16 element vertical array spanning the water column at about 3 km range. The communications signals are demodulated by time reversal multichannel combining followed by a single channel decision feedback equalizer using two subsets of array elements whose channel characteristics appear distinct: (1) top 10 and (2) bottom 4 elements. Due to rapid channel variations, continuous channel updates along with Doppler tracking are required prior to time reversal combining. This is especially true for the top 10 elements where the received acoustic field involves significant interaction with the dynamic ocean surface. The resulting communications performance in terms of output signal-to-noise ratio exhibits significant change over the 27 h transmission duration. This is particularly evident as the water column changes from well-mixed to a downward refracting environment.

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Section: Introductionmentioning

confidence: 99%

Impact of ocean variability on coherent underwater acoustic communications during the Kauai experiment (KauaiEx)

Song

Badiey²,

Song³

et al. 2008

The Journal of the Acoustical Society of America

106

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“…Investigation of these effects requires modeling or measurements of propagation parameters or acoustic communications directly, stretching over extended periods. [5][6][7] The present study reveals a strong tidal influence on the performance of a shallow-water communication link, for which the tidal range compares to the water depth. Further, the busy shipping traffic in the Western Scheldt gives rise to numerous instances of acoustic communication limited by shipgenerated noise or extinction by ship wakes, rather than reverberation.…”

Section: B Underwater Communication In Shallow Watermentioning

confidence: 99%

Coherent acoustic communication in a tidal estuary with busy shipping traffic

Walree

Neasham

Schrijver³

2007

The Journal of the Acoustical Society of America

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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.

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“…INTRODUCTION U NDERWATER acoustic channels are challenging for digital communications due to excessive multipath spread [1]. Further, the variability of the ocean environment can cause fluctuations of acoustic channels that can result in additional limitations on digital communications [2]- [4]. Among the dynamic ocean processes, internal waves can cause significant variation of acoustic pulses propagating in shallow water [5].…”

Section: Passive Time Reversal Acoustic Communicationsmentioning

confidence: 99%

“…The channel estimate is often obtained at the beginning of the data packet, denoted as , by channel probes or known symbols. Therefore, the output of time reversal combining is (1) where is the effective impulse response, or -function [22], using in time reversal combining (2) and denotes the complex conjugate and is the noise component after time reversal combining.…”

Section: Passive Time Reversal Acoustic Communicationsmentioning

confidence: 99%

Passive Time Reversal Acoustic Communications Through Shallow-Water Internal Waves

Song

Badiey

Newhall

et al. 2010

IEEE J. Oceanic Eng.

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Effects of tidally driven temperature fluctuations on shallow-water acoustic communications at 18 kHz

Cited by 42 publications

References 18 publications

Impact of ocean variability on coherent underwater acoustic communications during the Kauai experiment (KauaiEx)

Impact of ocean variability on coherent underwater acoustic communications during the Kauai experiment (KauaiEx)

Coherent acoustic communication in a tidal estuary with busy shipping traffic

Passive Time Reversal Acoustic Communications Through Shallow-Water Internal Waves

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