Results 201 to 210 of about 5,633 (244)

Active Sonar Waveform

2004
Abstract : JASON was tasked by the ONR to study the recent spate of whale-beaching events which have been linked to sonar exercises. The initial goal of the study was to use the current level of understanding of these events to recommend modifications of the sonar waveform as a mitigation strategy.
S. Flatte, C. Callan, M. Brenner, L. Bildsten, Hert Levine   +4 more
openaire   +1 more source

Waveguide invariance for active sonar.

The Journal of the Acoustical Society of America, 2009
Active sonar signal processing in shallow water has proven to be a challenging problem due to the strong interaction of sound with the boundaries of the channel and the dependence on typically unknown environmental parameters. This has motivated research on properties of acoustic propagation that are not sensitive to those factors, such as the ...
Jorge E. Quijano, Lisa M. Zurk
openaire   +1 more source

LPI waveforms for active sonar?

2004 IEEE Aerospace Conference Proceedings (IEEE Cat. No.04TH8720), 2004
The idea of a low probability of intercept (LPI) waveform is that its form is chaotic. It can of course be recalled by the transmitter (platform), and matched to what is received; but to the target it appears only as noise, and consequently the robust target receiver can only detect a rise in energy.
P. Willett, J. Reinert, R. Lynch
openaire   +1 more source

A PMHT algorithm for active sonar

SPIE Proceedings, 2004
ABSTRACT The Probabilistic Multi-Hypothesis Tracking (PMHT) algori thm proposed by Streit and Luginbuhl in 1995 is adapted here for use in active sonar applications. PMHT is a batch technique that uses the Expectation-Maximization (EM) algorithm to obtain MAP estimates of the sequence of target states. Probabilistic Multi-Hypothesis Tracking for Active
Christian G. Hempel, Sheri L. Doran
openaire   +1 more source

Neural networks for active sonar classification

Proceedings., 11th IAPR International Conference on Pattern Recognition. Vol.II. Conference B: Pattern Recognition Methodology and Systems, 2003
Active sonar classification has been a challenging pattern recognition problem for many years mainly due to the complexity of ocean environment. Improvement of sensors and data acquisition can be very costly and can only provide limited improvement in classification.
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Optimum Frequencies for Active Sonar

The Journal of the Acoustical Society of America, 1960
The method of determination of the optimum frequencies for active sonar without knowledge of the absolute values of the sonar set parameters, but only of their frequency dependence, appears to have been originated by J. W. Horton in about 1945 and is to be found in his recent text [J. W.
J. L. Stewart, E. C. Westerfield, M. K. Brandon   +2 more
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A Brief History of Active Sonar

Aquatic Mammals, 2009
As background for this special issue on strandings and mid-frequency active sonar (MFAS), this paper presents a brief history of active sonar, tracing the development of MFAS from its origins in the early 20th century through the development of current tactical MFAS.
Angela D'Amico, Richard Pittenger
openaire   +1 more source

Diversity in multistatic active sonar

Oceans '99. MTS/IEEE. Riding the Crest into the 21st Century. Conference and Exhibition. Conference Proceedings (IEEE Cat. No.99CH37008), 2003
A multistatic network of autonomous active transmitters and receivers, such as deployable underwater surveillance systems, often provides multiple contacts of the same target. The present paper examines the effects of receiver diversity ("spatial diversity") on a multistatic system, where three independent, spatially separated sonar receivers detect ...
L. Mozzone, S. Bongi, F. Filocca
openaire   +1 more source

Active sonar and the marine environment

AIP Conference Proceedings, 2004
A study of the effects of active sonar transmissions on fish and marine mammals in Norwegian waters has been launched following the ordering of new frigates by the Royal Norwegian Navy (RNoN). The frigates will be equipped with active sonars operating at lower frequencies than those of the sonars currently in operation in the RNoN.
openaire   +1 more source

A Theory of Active Sonar Detection

Proceedings of the IRE, 1959
The results of a theory of echo detection developed for radar are extended to sonar for the case of narrow-banid transmitted signals. The exposition specifically omits discussion of the decision problem and the statistical nature of the whole process of detection.
J. Stewart, E. Westerfield
openaire   +1 more source