Searched for: subject%3A%22Reverberation%22
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van Walree, P.A. (author), Colin, M.E.G.D. (author)
A channel sounding and communications experiment was performed in the Oslofjord, using eight bottom-mounted instrument units deployed in a network configuration. Five units were equipped with a software-defined 4–8-kHz acoustic modem, programmed to transmit probe signals and communication packets in a round-robin fashion. All transmitted...
article 2022
document
Binnerts, B. (author), Blom, K.C.H. (author), Giodini, S. (author)
Acoustic underwater communication is an enabler for the use of autonomous underwater vehicles (AUVs). AUVs can operate in acoustically challenging environments, e.g., near offshore platforms and in harbours. To realize robust underwater communication in such environments, the propagation conditions need to be properly understood. In this paper,...
conference paper 2017
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Ainslie, M.A. (author), Ellis, D.D. (author)
article 2017
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van Vossen, R. (author), Eidem, E.J. (author), Ivansson, S. (author), Chalindar, B. (author), Dybedal, J. (author), Colin, M.E.G.D. (author), Benders, F.P.A. (author), Andersson, B.L. (author), Juhel, B. (author), Cristol, X. (author), Olsen, G.K. (author), Pihl, J.N.B. (author), Tveit, E. (author), Jespers, S. (author), Ainslie, M.A. (author)
Accurate environmental information is required for obtaining confident sonar performance predictions. This environmental information is, however, often unreliable or unavailable. To support antisubmarine warfare (ASW) operations, a through-the-sensor approach has been developed in which relevant acoustic seabed properties are derived from...
article 2014
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Hunter, A.J. (author), van Vossen, R. (author)
Background reverberation can obscure useful features of the target echo response in broadband low-frequency sonar images, adversely affecting detection and classification performance. This paper describes a resolution and phase-preserving means of separating the target response from the background reverberation noise using a coherence-based...
article 2014
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Ainslie, M.A. (author), Ellis, D.D. (author), Ehrlich, J. (author), Schippers, P. (author), Hjelmervik, K.T. (author), Colin, M.E.G.D. (author)
The need for benchmarks of propagation loss was addressed by a series ofworkshops in the 1980s. The main results of those workshops were a set of well-defined propagation scenarios and their corresponding solutions. The availability of these benchmarks permitted the systematic evaluation of the accuracy of propagation models suitable for passive...
conference paper 2013
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Cristol, X. (author), Jespers, S. (author), Chalindar, B. (author), Juhel, B. (author), Dybedal, J. (author), Eidem, E.J. (author), Ivansson, S. (author), van Vossen, R. (author), Ainslie, M.A. (author), Andersson, B.L. (author), Colin, M.E.G.D. (author), Pihl, J. (author)
The European Defence Agency project RUMBLE-2 (ref.[1]) offered the opportunity for investigating experimentally acoustic reverberation at about 1.kHz, under grazing incidence (less than about 20°), from very porous clayey seafloors of a continental shelf (mean grain size spanning from about 7 to 10 in  units); the instrument was an operational,...
conference paper 2012
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Abrahamsson, L. (author), Andersson, B.L. (author), Ivansson, S. (author), Pihl, J. (author), Chalindar, B. (author), Cristol, J.X. (author), Juhel, B. (author), Eidem, E.J. (author), Dybedal, J. (author), Olsen, G.K. (author), Ainslie, M.A. (author), Benders, F.P.A. (author), Colin, M.E.G.D. (author), van Vossen, R. (author)
An operational low-frequency active sonar system has been used in the EDA (European Defence Agency) project Rumble-2 to collect reverberation data at sea trials in the North Sea. Using a fast ray model for the forward computations, the reverberation data are inverted to determine bottom parameters: Lambert back-scattering parameter μ and sound...
conference paper 2012
document
van Vossen, R. (author), Colin, M. (author), Benders, F. (author), Ainslie, M.A. (author), Eidem, E.J. (author), Chalindar, B. (author), Juhel, B. (author), Dybedal, J. (author), Olsen, G.K. (author), Ivansson, S. (author), Abrahamsson, L. (author)
Accurate environmental information is required for obtaining reliable predictions for the performance of low-frequency active sonar (LFAS) systems. This environmental information is, however, often unreliable or unavailable. For example, the acoustic seabed parameters relevant for the scattering and reflection of sound at the seabed are commonly...
conference paper 2011
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Juhel, B. (author), Cristol, X. (author), Chalindar, B. (author), Dybedal, J. (author), Eidem, E.J. (author), Ivansson, S. (author), van Vossen, R. (author), Ainslie, M.A. (author), Andersson, B.L. (author), Benders, F.P.A. (author), Colin, M.E.G.D. (author), Olsen, G.K. (author), Pihl, J. (author)
This paper presents the European Defence Agency project called “RUMBLE 2” carried out with contribution of several European organizations: TUS in France, TNO in the Netherlands, KDS and FFI in Norway, FOI in Sweden. The objective was to assess the capability of an operational Low Frequency Active Sonar (LFAS) to estimate bottom parameters in...
conference paper 2011
document
Cavallo, D. (author), Neto, A. (author), Gerini, G. (author)
Connected arrays constitute the only family of antenna arrays for which the spectral Green's Functions have been derived analytically. This formalism is extended here to the receiving case. When the arrays are assumed to be infinitely extended and periodically excited, rigorous equivalent networks can be derived to represent the electromagnetic...
article 2011
document
Zampolli, M. (author), Ainslie, M.A. (author)
In April 2010, a symposium in Memory of David Weston was held at Clare College in Cambridge (UK). International researchers from academia and research laboratories met to discuss two sets of test problems for sonar performance models, one aimed at understanding mammal echolocation sonar („Problem AI‟), and the other at benchmarking low frequency...
conference paper 2011
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Ainslie, M.A. (author), Harrison, C.H. (author), Zampolli, M. (author)
Previously published equations for the time dependence of the echo and reverberation in a Pekeris waveguide are combined with an expression derived for surface-generated noise. These closed form solutions are applied to the calculation of signal to reverberation ratio and signal to total background ratio for three CW pulses with centre...
conference paper 2011
document
Abrahamsson, L. (author), Andersson, B.L. (author), Ivansson, S. (author), Pihl, J. (author), Ainslie, M.A. (author), Benders, F.P.A. (author), Chalindar, B. (author), Colin, M.E.G.D. (author), Cristol, X. (author), Dybedal, J. (author), Eidem, E.J. (author), Juhel, B. (author), Olsen, G.K. (author), van Vossen, R. (author)
Reverberation is a problem for active sonar operating in shallow waters, reducing detection probabilities and introducing false alarms. Within the European Defence Agency project Rumble-2, a demonstrator system has been developed for ”through the sensor” measurement of the bottom parameters needed to predict active sonar detection performance....
conference paper 2011
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Calvo, D.C. (author), Rudd, K.E. (author), Zampolli, M. (author), Sanders, W.M. (author), Bibee, L.D. (author), TNO Defensie en Veiligheid (author)
We present calculations of acoustic scattering from an aluminum cylinder near a rough interface computed using the elastodynamic finite integration technique (EFIT): a time-domain numerical method useful for pulse propagation in inhomogeneous fluid–elastic environments. These calculations are relevant to the modeling of underwater acoustic...
article 2010
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Doisy, Y. (author), Deruaz, L. (author), van IJsselmuide, S.P. (author), Beerens, S.P. (author), Been, R. (author), TNO Defensie en Veiligheid (author)
Abstract—The influence of transmitted waveforms on the signal-to-reverberation ratio (SRR) of a low-frequency active sonar is analyzed both theoretically and experimentally. Reverberation experiments have been conducted during a sea trial in a littoral water environment in October 1999. The aim of the trials was to compare the performance of...
article 2008
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Naus, H.W.L. (author), TNO Defensie en Veiligheid (author)
A selection of the literature on the statistical description of electromagnetic fields and complex cavities is concisely reviewed. Some essential concepts, for example, the application of the central limit theorem and the maximum entropy principle, are scrutinized. Implicit assumptions, biased choices of variables and constraints, and some...
article 2008
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Ainslie, M.A. (author), TNO Defensie en Veiligheid (author)
Multipath ocean reverberation originating from the seabed in shallow isovelocity water, with particular attention to its information content in the cylindrical spreading and mode stripping regions, is considered. The reverberation is evaluated using Weston's flux integral method, both analytically with various simplifying approximations and...
article 2007
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Ainslie, M.A. (author), Boek, W. (author), Nielsen, P.L. (author), Harrison, C.H. (author), TNO Defensie en Veiligheid (author)
A measurement of reverberation provides an opportunity to estimate geoacoustic parameters of the seabed by searching the relevant parameter space for a combination of inputs that, when fed into a reverberation model, best matches the measured data. The success of this process relies in part on the accuracy of the reverberation model used. In...
conference paper 2007
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Ainslie, M.A. (author), van Walree, P.A. (author), Boek, W. (author), TNO Defensie en Veiligheid (author)
The performance of a sonar system operating in shallow water is closely linked to the properties of the seabed. At the same time the sensitivity of the acoustic signal (or background) to sediment properties gives an acoustic sensor the potential to measure precisely those properties that are needed to estimate sonar performance. Of particular...
conference paper 2007
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