Results 161 to 170 of about 3,360 (206)

Synthetic aperture active sonar imaging

[Proceedings] ICASSP-92: 1992 IEEE International Conference on Acoustics, Speech, and Signal Processing, 1992
The main problems involved in synthetic aperture sonar imaging are medium instability, slow mapping rate, and platform motion. Proposed solutions to these problems are reviewed, and a new technique for synthetic aperture sonar imaging is presented which allows a fast mapping rate and improved motion compensation.
Brett L. Douglas, Hua Lee
openaire   +1 more source

Adaptive waveform selection for active sonar

Proceedings of ICASSP '94. IEEE International Conference on Acoustics, Speech and Signal Processing, 2002
Investigates an adaptive waveform selection scheme where selection is based on overall tracking performance of the active sonar system. The assumption of an optimal receiver allows the inclusion of transmitted waveform specification parameters in the tracking sub-system equations, leading to a waveform selection scheme where the next transmitted ...
David J. Kershaw, Robin J. Evans 0001
openaire   +1 more source

Demonstration of the invariance principle for active sonar

The Journal of the Acoustical Society of America, 2008
Active sonar systems can provide good target detection potential but are limited in shallow water environments by the high level of reverberation produced by the interaction between the acoustic signal and the ocean bottom. The nature of the reverberation is highly variable and depends critically on the ocean and seabed properties, which are typically ...
Jorge E, Quijano, Lisa M, Zurk, Daniel, Rouseff   +2 more
openaire   +2 more sources

Performance improvement of localization for active sonars

2012 18th Asia-Pacific Conference on Communications (APCC), 2012
In sonar systems, the reverberation is a primary cause of false alarm. The multiple return association and localization (MRAL) algorithm is a data-fusion algorithm that can efficiently reduce the false alarm rate. The localization results of MRAL are lattice points that are the nearest points to targets in a searching area.
Eun-Jeong Jang, Dong Seog Han
openaire   +1 more source

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

Application of DORT to active sonar

Oceans '04 MTS/IEEE Techno-Ocean '04 (IEEE Cat. No.04CH37600), 2005
Active sonar in shallow water is often reverberation-limited and the detectability is often limited by the presence of too many false alarms. The problem of improving detection, and classification, in shallow water is being worked on in several different ways. The time reversal operator decomposition (DORT) is a technique that has recently been applied
C.F. Gaumond, D.M. Fromm, J. Lingevitch, R. Menis, G. Edelmann, D. Calvo, E. Kim   +6 more
openaire   +1 more source

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
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.
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