Browsing by Issue Date
Now showing items 701-720 of 882
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Target time smearing with short transmmissions and multipath propagation
(NURC, 2012/04)In active sonar the target echo level is often estimated with a propagation model that adds all multipath arrivals. If the (post-correlator) transmitted pulse is short compared to the multipath time spread then there is ... -
Antisubmarine warfare applications for autonomous underwater vehicles: the GLINT09 field trial results
(NURC, 2012/05)Surveillance in antisubmarine warfare (ASW) has traditionally been carried out by means of submarines or frigates with towed arrays. These techniques are manpower intensive. Alternative approaches have recently been suggested ... -
Adaptive autonomous underwater vehicles for littoral surveillance: the GLINT10 field trial results
(NURC, 2012/05)Autonomous underwater vehicles (AUVs) have gained more interest in recent years for military as well as civilian applications. One potential application of AUVs is for the purpose of undersea surveillance. As research into ... -
Counter piracy surveillance requirements for early detection, military rescue, or evasion
(NURC, 2012/06)Best practice for protection against pirates includes coordination with the military forces operating in the area, constant watch against the approach of pirates, and measures to prevent or delay their boarding. The time ... -
GLider Acoustics Sensing of Sediments (GLASS): experiments and data analysis
(CMRE, 2013/12)Seabed characteristics (geoacoustic properties and scattering strength) are critical parameters for sonar performance predictions. However, this bottom information is considered very difficult and expensive to achieve in ... -
Benefit assessment of glider adaptive sampling in the Ligurian Sea
(CMRE, 2014/01)The benefits of piloting a glider during a 6-day period via an adaptive sampling procedure in a 80 × 60 km2 marine area are assessed under a fully operational framework. The glider trajectory was adapted to reduce the ocean ... -
Underwater source localization using a hydrophone-equipped glider
(CMRE, 2014/01)Buoyancy-driven underwater gliders are autonomous underwater vehicles that were originally developed to collect oceanographic data. CMRE is studying the use of this technology for the characterization of denied areas, ... -
Range estimation of cetaceans with compact volumetric arrays
(CMRE, 2014/01)Passive acoustic monitoring is the method of choice to detect whales and dolphins that are acoustically active and to monitor their underwater behaviour. The NATO Science and Technology Organization Centre for Maritime ... -
Vessel pattern knowledge discovery from AIS data: a framework for anomaly detection and route prediction
(CMRE, 2014/01)Understanding maritime traffic patterns is key to Maritime Situational Awareness applications, in particular, to classify and predict activities. Facilitated by the recent build-up of terrestrial networks and satellite ... -
A novel approach for a bistatic scattering calculation suitable for sonar performance model
(CMRE, 2014/01)One of the classical approaches to the calculation of the sound pressure scattered from a rough surface is to sum the contributions to the field from a set of small tiles that approximate the surface. If the tiles are ... -
Performance assessment of the MUSCLE synthetic aperture sonar
(CMRE, 2014/01)Synthetic Aperture Sonar (SAS) systems are quickly becoming fundamental tools for seabed mapping applications, as they provide high resolution imagery independent of range from the sensor, with high area coverage rates. ... -
Ray convergence in a flux-like propagation formulation
(CMRE, 2014/01)The energy flux formulation of waveguide propagation is closely related to the incoherent mode sum, and its simplicity has led to development of efficient computational algorithms for reverberation and target echo strength, ... -
A relation between multipath group velocity, mode number, and ray cycle distance
(CMRE, 2014/01)Weston's ray invariant or "characteristic time" in a range-dependent environment is exactly equivalent to the Wentzel-Kramers-Brillouin phase integral for ducted normal modes. By considering a ray element it is shown that ... -
Localization of small surface vessels through acoustic data fusion of two tetrahedral arrays of hydrophones
(CMRE, 2014/01)Detection and tracking of vessels is important in confined areas such as marine parks or harbors. Nowadays, the presence of ships can be accurately monitored either by radar or via AIS system, while small vessels, which ... -
Efficient dense sonar surveys with an autonomous underwater vehicle
(CMRE, 2014/01)An algorithm for the in situ adaptation of the survey route of an autonomous underwater vehicle (AUV) equipped with side-looking sonars was recently proposed. This algorithm immediately exploits the through-the-sensor data ... -
Optimum sampling designs for a glider-mooring observing network
(CMRE, 2014/01)Ocean observing systems (OOSs) constituted by moorings and gliders are becoming relevant in oceanographic and climate studies. In these observing networks, the temporal variability is captured by mooring observations, while ... -
Oceanographic field estimates from remote sensing and glider fleets
(CMRE, 2014/01)This work investigates the merging of temperature observations from a glider fleet and remote sensing, based on a field experiment conducted in an extended coastal region offshore La Spezia, Italy, in August 2010. Functional ... -
Maritime surveillance using multiple high-frequency surface-wave radars
(CMRE, 2014/05)In the last decades, great interest has been directed toward low-power high-frequency (HF) surface-wave radars as long-range early warning tools in maritime-situational-awareness applications. These sensors, developed for ... -
Detection, tracking and fusion of multiple HFSW radars for ship traffic surveillance: experimental performance assessment
(CMRE, 2014/05)Low-power HF surface-wave radars fit well the role of long-range early-warning tools in maritime situational awareness applications, by virtue of their over-the-horizon coverage capability and continuoustime mode of ...