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Formal Reports

Report of results of completed projects or major milestones either in scientific terms or in terms acceptable to a wider audience. Note: Unless linked to the full text, reports are only available to NATO member nations from designated distribution centres. 

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TALON 13 demonstration report TALON 13 demonstration report

Date added: 10/07/2015
Date modified: 10/07/2015
Filesize: Unknown

TALON 13 demonstration report. Oddone, Manlio; Francis, Christopher S.; D'Amaro, Luigi; Fioravanti, Stefano; Grati, Alberto; Mannoni, Andrea; Bertagna, Davide; Zappa, Giovanni; Stipanov, Marin; Jourden, Nicolas. CMRE-FR-2015-003. February 2015.

This work looks at a prototype harbour protection system, "TALON", developed at the NATO Centre for Maritime Research and Experimentation (CMRE) for the purpose of demonstrating a potential capability to defend units, facilities and infrastructure in ports and harbours, against asymmetric threats posed by small boats, swimmers and divers. Combining rapid contact designation and warning (i.e. comprising detection, tracking, inspection, friend/foe classification and alert) with delivery of proportional, non-lethal response, TALON is designed to safely and effectively warn off innocent contacts, and to establish proof of hostile intent in the event of an attack. Primary focus lay in demonstrating the concepts that a scalable number of sensor-effector clusters can be deployed during expeditionary missions to provide the above capabilities in a largely automated fashion, and increased robustness and effectiveness can be achieved through the implementation of interchangeable mobile C2 devices and by integrating data fusion capabilities. Concepts were successfully demonstrated to stakeholders at CMRE during "TALON 13" exercises, in which live vignettes were executed by members of the Italian Navy to simulate a variety of intrusion scenarios against the system.

Adaptive Bayesian behaviors for autonomous underwater vehicle surveillance networks Adaptive Bayesian behaviors for autonomous underwater vehicle surveillance networks

Date added: 10/07/2015
Date modified: 10/07/2015
Filesize: Unknown

Adaptive Bayesian behaviors for autonomous underwater vehicle surveillance networks.  Goldhahn, Ryan A.; Braca, Paolo; LePage, Kevin D. CMRE-FR-2015-002. January 2015.

Autonomous underwater vehicles (AUVs) present a low-cost alternative or supplement to existing underwater surveillance networks. The NATO Centre for Maritime Research and Experimentation (CMRE) is developing multi-sensor data fusion techniques and collaborative autonomous behaviours to improve the performance of multistatic networks of AUVs for the purpose of underwater surveillance. In this work, a range-dependent acoustic model for the predicted probability of target detection is combined with the detections observed on all available platforms in a Bayesian framework to compute a posterior distribution on target position for each ping. This posterior is then used by the AUVs to collectively optimize their future actions based on a mission-driven measure of network performance. A Bernoulli filter is used to jointly estimate both the target state and whether zero or one target is present. Simulation results are presented quantifying the performance increase using these adaptive behaviours over traditional pre-planned trajectories.

Bayesian inference of seabed geoacoustic and scattering properties using the DREAMzs algorithm Bayesian inference of seabed geoacoustic and scattering properties using the DREAMzs algorithm

Date added: 10/07/2015
Date modified: 10/07/2015
Filesize: Unknown

Bayesian inference of seabed geoacoustic and scattering properties using the DREAMzs algorithm.  Nielsen, Peter L.; Canepa, Gaetano; Fox, Warren L. J. CMRE-FR-2015-001. January 2015.

The probability of mine burial and sonar performance prediction are strongly dependent on the seabed properties. In particular, for low-frequency mine-hunting sonar operations focusing on detection and classification of partial or fully buried targets, the transmitted acoustic field has significant interaction with the seabed. CMRE is in the process developing a sonar system operating at lower acoustic frequencies compared to more traditional mine-hunting sonars, and the intention is to use this sonar system to determine the seabed properties as the mine hunting mission progresses. This report describes a methodology to estimate the unknown seabed geoacoustic and scattering properties with associated uncertainties tailored to the CMRE low-frequency sonar. The algorithm is composed of an acoustic model developed at CMRE to calculate the backscattered intensity from a layered seabed as a function of geoacoustic, interface and volume scattering properties. This acoustic model is linked to an inversion package based on a Bayesian framework to provide the best estimate and uncertainties of the seabed properties. The performance of this environmental characterization algorithm is demonstrated for synthetically generated test cases which mimic the operation of the CMRE low-frequency mine-hunting sonar. The test cases are at present limited to a fine silt bottom type described as an infinite halfspace with water-seabed interface and volume scattering. Both noise free and noisy synthetically generated data are analyzed, and different run parameters for the inversion package are changed to evaluate the impact on the inferred seabed properties. The added noise is treated as an unknown together with the seabed properties. The geoacoustic and scattering parameters are well determined for the noise free cases, while only sediment sound speed, volume scattering spectral level and added noise are well estimated for the noisy test cases.

Coupled forward and inverse radiative transfer modelling Coupled forward and inverse radiative transfer modelling

Date added: 01/15/2015
Date modified: 01/15/2015
Filesize: Unknown

Coupled forward and inverse radiative transfer modelling.  Sanjuan Calzado, Violeta; Fournier, Georges. CMRE-FR-2014-027. December 2014.

The optical signature in the ocean is a result of the absorption and scattering processes in the medium with particles. Calculating the radiant field from these absorption and scattering interactions is a well known problem. The radiant distribution is calculated from the radiative transfer equation, where state of the art models are able to reproduce similar boundary conditions as in the environment. The inverse problem, where the absorption and scattering processes are calculated given a radiant distribution, has only been attempted once with numerical formulations. Gordon's algorithm is discussed here and evaluated for success under a variety of different types of scenarios. The algorithm convergence in shallow water scenarios with high bottom reflectivity and sediment resuspension is moderate with average convergence of 50%, whereas in oceanic stations it is less than 5%, even in scenarios presenting vertical stratification. However, the calculation time is very high and therefore it is notappropriate for implementation in any operational system. Based on Gordon's formulation, a new inversion algorithm has been developed, with excellent results compared with Gordon's approach. The algorithm does not include a forward radiative transfer model; therefore the computational time required is minimal. Initial tests have shown excellent agreement when introduced in an iterative fashion with a forward radiative transfer model compared with measured absorption and backscattering data.

An analysis of the multistatic employment of low frequency active sonar An analysis of the multistatic employment of low frequency active sonar

Date added: 01/15/2015
Date modified: 01/15/2015
Filesize: Unknown

An analysis of the multistatic employment of low frequency active sonar.  Strode, Christopher. CMRE-FR-2014-028. December 2014.

This work examines a number of metrics and operational analysis techniques to explore the potential employment of Low frequency Active Sonar (LFAS) within multistatic networks. The analysis considers the combined sonar area coverage of a number of monostatic and bistatic configurations including LFAS operating in conjunction with sonobuoys and helicopter dipping sonar. The conclusions of this study may be used to update the current Surface Ship Multistatic Sonar EXTAC which has been drafted by the United Kingdom, France and Canada.

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