Waveguides

Medwin, Herman; Clay, C. S.

doi:10.1016/b978-012487570-8/50013-1

Cited by 48 publications

(108 citation statements)

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“…Scattering of signals in strongly wind-influenced surface layers will, due to air bubbles (Medwin & Clay, 1998) and multipath (Dol et al, 2013), not only increase the sound attenuation in these layers, but also contribute to increased background noise levels, even at larger depth.…”

Section: Variables Influencing Detection Probabilitymentioning

confidence: 99%

“…The most important limitation is related to the ability of a receiver to detect the signals from tagged animals in its vicinity. This so-called detection probability depends on many factors, which are linked to the physical characteristics of sound propagation through the water column (Medwin & Clay, 1998;Gjelland & Hedger, 2017), and can change over space and time. As a consequence, the successful application of acoustic telemetry and the correct interpretation of detection and movement data depend upon proper knowledge of the detection range (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Environmental factors influence the detection probability in acoustic telemetry in a marine environment: results from a new setup

et al. 2018

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Acoustic telemetry is a commonly applied method to investigate the ecology of marine animals and provides a scientific basis for management and conservation. Crucial insight in animal behaviour and ecosystem functioning and dynamics is gained through acoustic receiver networks that are established in many different environments around the globe. The main limitation to this technique is the ability of the receivers to detect the signals from tagged animals present in the nearby area. To interpret acoustic data correctly, understanding influencing factors on the detection probability is critical. Therefore, range test studies are an essential part of acoustic telemetry research. Here, we investigated whether specific environmental factors (i.e. wind, currents, waves, background noise, receiver tilt and azimuth) influence the receiver detection probability for a permanent acoustic receiver network in Belgium. Noise and wind speed in relation to distance, the interaction of receiver tilt and azimuth and current speed were the most influential variables affecting the detection probability in this environment. The study indicated that there is high detection probability up to a distance of circa 200 m. A new setup, making use of features that render valuable information for data analysis and interpretation, was tested and revealed general applicability.

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Section: Variables Influencing Detection Probabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Environmental factors influence the detection probability in acoustic telemetry in a marine environment: results from a new setup

et al. 2018

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“…음선추적은 음속이 변하는 매질 내에서 깊이가 변하여도, 입사각과 음속의 비는 일정한 값을 갖 게 되는 스넬의 법칙 [9,10] 을 이용하였다. 이, 감쇄손실 모델로는 Francois-garrison 모델 [12] 이 사용되었다.…”

Section: 음선추적 알고리즘unclassified

High-frequency Reverberation Simulation of High-speed Moving Source in Range-independent Ocean Environment

Kim

Lee²,

You³

et al. 2013

The Journal of the Acoustical Society of Korea

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ABSTRACT:In a shallow water waveguide, reverberation signals and their Doppler effects form the primary limitation on sonar system performance. Therefore, in the reverberation-limited environment, it is necessary to estimate the reverberation level to be encountered under the conditions in which the sonar system is operated. In this paper, high-frequency reverberation model capable of simulating the reverberation signals received by a high-speed moving source in a range independent waveguide is suggested. In this model, eigenray information from the source to each boundary is calculated using the ray-based approach and the optimizing method for the launch angles. And the source receiving position changed by the moving source is found by a scattering path-finding algorithm, which considers the speed and direction of source and sound speed to find the path of source movement. The scattering effects from sea surface and bottom boundaries are considered by APL-UW scattering models. The model suggested in this paper is verified by a comparison to the measurements made in August 2010. Lastly, this model reflects well statistical properties of the reverberation signals.

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“…The experimental ranges are given in Table 2. The signals presented in this paper were acquired at a maximum range of 27 m. This short range is mostly due to the high sound absorption loss (100 dB/km at 20 °C and at 300 kHz [20]). Since the equipment did not have the ability to perform real-time MIMO communication, each source was used individually and the MIMO messages were constructed off-line.…”

Section: Methodsmentioning

confidence: 99%

MIMO Underwater Acoustic Communications in Ports and Shallow Waters at Very High Frequency

Real

Beaujean

Bouvet

2013

JSAN

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Abstract:Hermes is a Single-Input Single-Output (SISO) underwater acoustic modem that achieves very high-bit rate digital communications in ports and shallow waters. Here, the authors study the capability of Hermes to support Multiple-Input-Multiple-Output (MIMO) technology. A least-square channel estimation algorithm is used to evaluate multiple MIMO channel impulse responses at the receiver end. A deconvolution routine is used to separate the messages coming from different sources. This paper covers the performance of both the channel estimation and the MIMO deconvolution processes using either simulated data or field data. The MIMO equalization performance is measured by comparing three relative root mean-squared errors (RMSE), obtained by calculations between the source signal (a pseudo-noise sequence) and the corresponding received MIMO signal at various stages of the deconvolution process; prior to any interference removal, at the output of the Linear Equalization (LE) process and at the output of an interference cancellation process with complete a priori knowledge of the transmitted signal. Using the simulated data, the RMSE using LE is −20.5 dB (where 0 dB corresponds to 100% of relative error) while the OPEN ACCESSJ. Sens. Actuator Netw. 2013, 2 701 lower bound value is −33.4 dB. Using experimental data, the LE performance is −3.3 dB and the lower bound RMSE value is −27 dB.

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Waveguides

Cited by 48 publications

References 0 publications

Environmental factors influence the detection probability in acoustic telemetry in a marine environment: results from a new setup

Environmental factors influence the detection probability in acoustic telemetry in a marine environment: results from a new setup

High-frequency Reverberation Simulation of High-speed Moving Source in Range-independent Ocean Environment

MIMO Underwater Acoustic Communications in Ports and Shallow Waters at Very High Frequency

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