Channel Measurement System Design and Noise Characterization for Acoustic Water Pipe Channels PDF Download
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Author: Amartansh Dubey
Publisher:
ISBN:
Category :
Languages : en
Pages : 163
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Author: Amartansh Dubey
Publisher:
ISBN:
Category :
Languages : en
Pages : 163
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Author: Andreja Radošević
Publisher:
ISBN: 9781267433497
Category :
Languages : en
Pages : 186
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In this dissertation, we consider design aspects of spectrally efficient underwater acoustic (UWA) communications. In particular, we first focus on statistical characterization and capacity evaluation of shallow water acoustic communications channels. Wideband single-carrier and multi-carrier probe signals are employed during the Kauai Acoustic Communications MURI 2008 (KAM08) and 2011 (KAM11) experiments, to measure the time-varying channel response, and to estimate its statistical properties and capacity that play an important role in the design of spectrally efficient communication systems. Besides the capacity analysis for unconstrained inputs, we determine new bounds on the achievable information rate for discrete-time Gaussian channels with inter-symbol interference and independent and uniformly distributed channel input symbols drawn from finite-order modulation alphabets. Specifically, we derived new bounds on the achievable rates for sparse channels with long memory. Furthermore, we explore design aspects of adaptive modulation based on orthogonal frequency division multiplexing (OFDM) for UWA communications, and study its performance using real-time at-sea experiments. Lastly, we investigate a channel estimation (CE) method for improving the spectral efficiency of UWA communications. Specifically, we determine the performance of a selective decision directed (DD) CE method for UWA OFDM-based communications.
Author: Abu Hena Muntakim
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Acoustic emission (AE) method is becoming popular for leak detection in municipal water mains where leaks are identified and the locations are determined through interpretation of measured acoustic signals without any excavation or disruption of services. For the interpretation of signals, several parameters such as frequency band of signals, coherence between signals, and cross-correlation between signals are employed. However, published literature lack data on applicability of the AE method under various field conditions. This research presents field investigation of leak detection using AE method, identification of leak noise source, leak noise attenuation characteristics and finite element (FE) simulation of acoustic wave propagation through fluid filled pipe. The field application of the AE method was performed through measuring acoustic noise at two points bracketing the leak along the pipe length in the City of Mount Pearl in Newfoundland and Labrador, Canada. For a better understanding of the source of leak noise, a preliminary laboratory investigation was conducted under a controlled environment. At low flow rates, it was found that water (escaping from the leak) hits surrounding obstacles and generates the leak noise. To explore the characteristics of leak noise, a new laboratory facility was developed and the attenuation characteristics of the leak noise was investigated. Leak noise attenuation was found to depend on the flow rate of the water. Finally, finite element (FE) method was used for modelling of acoustic wave propagation and attenuation characteristics. A commercially available FE software "ABAQUS" was used. FE analysis reveals that acoustic leak noise can propagate up to 150 m before attenuating to the ambient noise level in water mains.
Author: Xavier Lurton
Publisher: Springer Science & Business Media
ISBN: 9783540429678
Category : Science
Languages : en
Pages : 386
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Presented in a clear and concise way as an introductory text and practical handbook, the book provides the basic physical phenomena governing underwater acoustical waves, propagation, reflection, target backscattering and noise. It covers the general features of sonar systems, transducers and arrays, signal processing and performance evaluation. It provides an overview of today's applications, presenting the working principles of the various systems. From the reviews: "Presented in a clear and concise way as an introductory text and practical handbook, the book provides the basic physical phenomena governing underwater acoustical waves, propagation, reflection, target backscattering and noise. ⦠It provides an overview of todayâs applications, presenting the working principles of the various systems." (Oceanis, Vol. 27 (3-4), 2003) "This book is a general survey of Underwater Acoustics, intended to make the subject âas easily accessible as possible, with a clear emphasis on applications.â In this the author has succeeded, with a wide variety of subjects presented with minimal derivation ⦠. There is an emphasis on technology and on intuitive physical explanation ⦠." (Darrell R. Jackson, Journal of the Acoustic Society of America, Vol. 115 (2), February, 2004) "This is an exciting new scientific publication. It is timely and welcome ⦠. Furthermore, it is up to date and readable. It is well researched, excellently published and ranks with earlier books in this discipline ⦠. Many persons in the marine science field including acousticians, hydrographers, oceanographers, fisheries scientists, engineers, educators, students ⦠and equipment manufacturers will benefit greatly by reading all or part of this text. The author is to be congratulated on his fine contribution ⦠." (Stephen B. MacPhee, International Hydrographic Review, Vol. 4 (2), 2003)
Author:
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ISBN:
Category : Nuclear energy
Languages : en
Pages : 852
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Author:
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ISBN:
Category : Weights and measures
Languages : en
Pages : 964
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Author: Bo Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 68
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In recent years, interests in Underwater Acoustic (UWA) communications have exponentially grown due to many emerging commercial and military applications such as ocean pollution monitoring, off-shore oil exploration and data telemetry, oceanic environment sensing and surveillance, underwater wireless sensor networking, submarine communications, and so on. The UWA channels have specific properties which differ from radio channels, which make it a big challenge to apply current radio wireless systems to it directly. There are three main characters attached in UWA channels: low speed of sound that varies with medium conditions; attenuation that increases with both transmission range and frequency; time-varying multipath propagation that depends on boundary conditions. The wireless communication systems build on UWA channels would suffers from limited bandwidth, long multipath delays, large Doppler shift and spread which means low data rate, sever inter symbol interference (ISI) and complex equalization. The design and analysis of underwater acoustic communication systems rely on the fundamental characterization of underwater acoustic signal propagation. Several channel models have been developed to investigate channel properties in different environment set ups. Currently, there are no standardized models for acoustic channel fading. There are two kinds of models developed so far for different purposes: deterministic models and statistical models. While the former one focuses on the reflections when boundary conditions are fixed, the latter one concentrates on overall channel's statistical probability distributions with changing boundaries. Statistical models raise too much debate and the assumptions of the models with various statistical distributions remain to be further tested. On the other hand, many deterministic models have been tested and implemented as appropriate tools to investigate the reflection and refraction behavior of underwater acoustic signal propagation. In this thesis, we aim to study the power delay profile of underwater acoustic communication channels for given specific system configuration. Specifically, we investigated the multipath channel impulse responses of underwater acoustic channels by considering firstly a deterministic ray/beam tracing model and then a statistically random environment. We simulated an underwater acoustic channel model on MATLAB based on geometry of transceiver and surrounding environment and wave propagation equations. The amplitude and delays of the multipath channel impulse responses were compared and analyzed for underwater acoustic channels with various transceiver configurations such as range, depth, frequency, random water surface and bottom. Simulation results show that the depth location of underwater transceivers does not affect much the delay profile of the multipath received signals, however, it does change the power distribution of the multipath signals as the closer the transceiver to the boundaries, the less power received. Regarding various ranges between the transmitter and receiver, it is interesting to observe that the power delay profile of the multipath signals vary randomly, and the number of delay paths is uncorrelated to the ranges. Regarding underwater acoustic communication with different frequencies, while the delay profile of multipath signals remains stable with the same system geometry, the attenuation of multipath signals decreases as the frequency of acoustic signals increases. Moreover, the boundary conditions (water surface and/or bottom) of underwater acoustic channel affect the power delay profile of multipath signals significantly. In both fixed boundary and randomly varying boundary (e.g. water surface waves), the power delay profile of multipath signals exhibits a random pattern, which raises significant challenge in channel estimation in underwater acoustic communication. Our findings are helpful to the design of high-rate underwater acoustic communication systems. Our ultimate goal is to apply the MIMO-OFDM concept in underwater communication scenario in order to increase the date rate of underwater acoustic communication systems, in which channel estimation, channel multipath mitigation, signal processing, and data detection, need to be redesigned properly to take into account the unique characteristics of underwater acoustic channels.
Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 994
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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 888
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Author:
Publisher:
ISBN:
Category : Marine biology
Languages : en
Pages : 364
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