Browsing by Title
Now showing items 405-424 of 882
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Incoherent sub-band averaging for improved target detection and Doppler estimation in linearly frequency modulated continuous active sonar
(CMRE, 2019/05)Linear frequency modulated (LFM) continuous active sonar (CAS) waveforms show promise for use in target tracking given that waveforms can be split into sub-waveforms (sub-bands), thereby increasing the target refresh rate. ... -
Increasing the operational safety of autonomous underwater vehicles using the JANUS communication standard
(CMRE, 2019/05)Increasing the operational safety of Autonomous Underwater Vehicles (AUVs) is necessary to fully explore their potential. Currently, AUV operations are limited by several constrains including the need to guarantee no ... -
Influence of background-noise spatial coherence on high-resolution passive method
(NATO. SACLANTCEN, 1982/06)New signal processing methods for passive listening have appeared recently : they are called "high resolution" methods because they have theoretically a better resolving power than conventional or adaptive beamforming . ... -
Influence of internal waves on sound propagation in the SOFAR channel
(NATO. SACLANTCEN, 1975/10)In this paper theoretical investigations due to the influence of internal waves to sound propagation in the SOFAR-channel are presented. The undisturbed acoustic field is described by a normal-mode model. The disturbance ... -
Information and source quality ontology in support of maritime situational awareness
(CMRE, 2019/05)To support situation awareness, the benefit of using a variety of sources is undeniable although it brings additional challenges related to possible conflicting information, heterogeneity in data formats, semantics, ... -
Infrared detection of marine mammals
(NURC, 2005/12)An infrared (IR) binocular, designed for in-the-field military applications, was tested using in situ marine mammals during the Mar Ligure Joint Experiment 2003 (MLJX03) that took place in August-September 2003 onboard the ... -
Instrumentation for crosshole geoacoustic measurements in unconsolidated sediments
(NATO. SACLANTCEN, 1994/06)Research tools are described that enable direct measurements of sediment properties as a function of depth in unconsolidat,ed sediments. The first tool is a hole making device that sits on the sea floor and utilizes pneumatic ... -
Intensity and phase fluctuations in low-frequency acoustic transmission through internal waves
(NATO. SACLANTCEN, 1975/10) -
Intensity at caustics
(NATO. SACLANTCEN, 1971/12)The classical divergence expressions predict an infinite intensity at caustics. This infinite intensity is a fundamental limitation of geometrical acoustics (ray theory). The intensity at a caustic is of primary concern ... -
Intensity calculations along a single ray
(NATO. SACLANTCEN, 1974/02)A method is presented for the calculation of sound intensity using only one ray. The sound-velocity profile is assumed to be continuous up to the second derivative and it is supposed that the ray equations are solved ... -
Intensity calculations along a single ray
(NATO. SACLANTCEN, 1971/12)A method is presented for the calculation of sound intensity using only one ray. The sound velocity profile is assumed to be continuous up to the second derivative and it is supposed that the ray equations are solved ... -
Intensity moments of underwater sound scattered by a Gaussian spectrum corrugated surface: measurements and comparison with a catastrophe theory approximation
(NATO. SACLANTCEN, 1997)An underwater forward-scattering investigation was undertaken with random rough corrugated pressure release surface manufactured out of Styrofoam. Measured wavefields associated with the reflection caustics agree with ... -
Intensity-range relations for shallow-water sound propagation
(NATO. SACLANTCEN, 1976/04)Convincing experimental evidence is presented to show that various "decay laws" for the decrease of sound intensity with increasing range can give high-quality representation for shallow water data. However, while a sequence ... -
Interactive tools for the exploration and analysis of multibeam and other seafloor acoustic data
(NATO. SACLANTCEN, 1997)The Ocean Mapping Group has developed a full suite of software tools for the real-time or near real-time display, editing, quality control, interpretation and visualization of multibeam sonar data. The combination of ... -
Interface wave studies on the Ligurian shelf usingan OBS array: experimental results and propagation models
(NATO. SACLANTCEN, 1986/06)Seismic waves travelling in the water/sediment or subbottom sediment/sediment interface have been the subject of considerable interest in recent years. Experiments have confirmed the existence of interface waves in different ... -
Interface-wave propagation studies: an example of seismo-acoustic propagation in non-homogeneous materials
(NATO. SACLANTCEN, 1990/01)This study addresses the problem relating to the interaction processes -
Intermediate water downstream of the Strait of Sicily
(NATO. SACLANTCEN, 1972/09)In July 1970 the ATLANTIS II sailed through the western Mediterranean providing an opportunity to make a quasi-synoptic observation of the Levantine Intermediate Water between the Strait of Gibraltar and the Strait of ... -
Internal oceanographic microstructure phenomena
(NATO. SACLANTCEN, 1975/10)This paper is concerned with the nature and causes of both fine structure and microstructure in the ocean. Following an account of the acoustic/oceanographic background to subject, the characteristics of fine structure are ... -
Interpretation and fusion of sonar images using evidential reasoning
(NATO. SACLANTCEN, 1995/12)A method and system architecture for automatic interpretation and fusion of multiple sonar images is proposed. The interpretation of a sonar image consists of the creation of a symbolic geographical map indicating the ... -
Interpretation and representation of the synoptic features in the Iceland-Faeroe-Shetland region
(NATO. SACLANTCEN, 1993/07)The kinematic structure of the sub-inertial fluctuations of measured current and temperature fields from 6 moorings deployed during the June