Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 27 for “"Acoustic channel"”.
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Single mode excitation in the shallow water acoustic channel using feedback control
The shallow water acoustic channel supports far-field propagation in a discrete set of modes. Ocean experiments have confirmed the modal nature of acoustic propagation, but no experiment has successfully excited only one of the suite of mid-frequency propagating modes propagating in a coastal …
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K-distribution fading models for Bayesian estimation of an underwater acoustic channel
Current underwater acoustic channel estimation techniques generally apply linear MMSE estimation. This approach is optimal in a mean square error sense under the assumption that the impulse response fluctuations are well characterized by Gaussian statistics, leading to a Rayleigh distributed …
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Single mode excitation in the shallow water acoustic channel using feedback control
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.
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K-distribution fading models for Bayesian estimation of an underwater acoustic channel
Current underwater acoustic channel estimation techniques generally apply linear MMSE estimation. This approach is optimal in a mean square error sense under the assumption that the impulse response fluctuations are well characterized by Gaussian statistics, leading to a Rayleigh distributed …
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Inter-carrier interference mitigation for underwater acoustic communications
… is challenging. Such communications must be acoustic in order to travel long distances. The underwater acoustic channel has a long delay spread, which makes orthogonal frequency division multiplexing (OFDM) an attractive communication scheme. However, the underwater acoustic channel is highly …
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Acoustic signal estimation using multiple blind observations
… thesis proposes two algorithms for recovering an acoustic signal from multiple blind measurements made by sensors (microphones) over an acoustic channel. Unlike other algorithms that use a posteriori probabilistic models to fuse the data in this problem, the proposed algorithms use results …
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Adaptive reception for underwater communications
… In this type of wireless link, the radio channel is replaced by an underwater acoustic channel, which is strongly dependent on the physical properties of the ocean medium and its boundaries, the link geometry and the ambient noise. Traditional acoustic communications have involved a priori …
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Autonomous adaptive acoustic relay positioning
We consider the problem of maximizing underwater acoustic data transmission by adaptively positioning an autonomous mobile relay so as to learn and exploit spatial variations in channel performance. The acoustic channel is the main practical method of underwater wireless communication and improving …
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A distributed approach to underwater acoustic communications
A novel distributed underwater acoustic networking (UAN) protocol suitable for ad-hoc deployments of both stationary and mobile nodes dispersed across a relatively wide coverage area is presented. Nodes are dynamically clustered in a distributed manner based on the estimated position of one-hop …
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Array Signal Processing for Communications from High Altitude Platforms and Other Applications
… data rate OFDM signal transmission in underwater acoustic channel are respectively investigated. Both conventional and adaptive beamforming methods are investigated in the application to HAP communications. A three-step footprint optimization method based on planar array and hexagonal cellular …
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Underwater sound propagation and acoustic communication in a time-varying shallow estuarine environment
… other coastal engineering activities. Underwater acoustic technology offers a series of effective applications and technical supports for real-time monitoring and long-term preservation of the nature environment and ecosystem in these regions. However, estuaries are shallow waters with complicated …
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Design and analysis of a high-rate acoustic link for underwater video transmission
A high bit rate acoustic link for underwater video transmission is examined. Currently, encoding standards support video transmission at bit rates as low as 64 kbps. While this rate is still above the limit of commercially available acoustic modems, prototype acoustic modems based on phase coherent …
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A Graphical Model for the Communications Channel
We consider the problem of channel modeling and channel estimation. The widely used wide sense stationary uncorrelated scattering model for the communications channel neglects correlations between different multipath arrivals, but this seems to oversimplify the real channel in many cases. One …
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Microphone array processing for augmented listening
… implementation issues are considered, including acoustic channel estimation, the design of wearable microphone arrays, the acoustic effects of the body, and models and algorithms for deformable microphone arrays. Finally, the performance of the listening system is improved by cooperative …
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Modeling wireless acoustic power transmission systems
… prevents penetration of electromagnetic energy, acoustic wave transmission is often used for data communications and could be a viable option for wireless power transfer. Such a power transfer system design would need to incorporate the behavior of the entire acoustic channel, taking into account …
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Analysis of and techniques for adaptive equalization for underwater acoustic communication
… ocean science, defense, and homeland security. Acoustics remains the only practical means of accomplishing long-range communication in the ocean. The acoustic communication channel is fraught with difficulties including limited available bandwidth, long delay-spread, time-variability, and …
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Analysis of and techniques for adaptive equalization for underwater acoustic communication
… ocean science, defense, and homeland security. Acoustics remains the only practical means of accomplishing long-range communication in the ocean. The acoustic communication channel is fraught with difficulties including limited available bandwidth, long delay-spread, time-variability, and …
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Acoustic data communication system for in-pipe wireless sensor networks
… unit, it is proposed to use the pipeline as an acoustic waveguide for the transmission of appropriately modulated acoustic waves that encapsulate the digital data, since radio frequency transmission is not feasible underground. The confined acoustic channel imposes severe distortion on the …
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A channel subspace post-filtering approach to adaptive equalization
… interference (ISI) due to multipath. Underwater acoustic communications is one such type of wireless communications in which the channel is highly dynamic and the amount of ISI due to multipath is relatively large. In the underwater acoustic channel, associated with each of the deterministic …
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A super-nyquist architecture for rateless underwater acoustic communication
… for reliably communicating over the underwater acoustic channel. A notable feature of this architecture is its rateless property: the receiver simply collects pieces of transmission until successful decoding is possible. With this, we aim to achieve capacity-approaching communication under a …
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