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Memorandum Reports

Report that covers interim results during the course of a project. Note: Unless linked to the full text, reports are only available to NATO member nations from designated distribution centres.


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Civilian Monitoring Network (CMN) high level report Civilian Monitoring Network (CMN) high level report

Date added: 02/05/2016
Date modified: 02/05/2016
Filesize: Unknown

Civilian Monitoring Network (CMN) high level report. Collins, Michael. CMRE-MR-2015-018. January 2016.

The advent of low cost hydrophones and the electronics necessary to record, process, and disseminate recordings has led to an increase in the amount of recording equipment deployed in the ocean for nonmilitary purposes. Installations of recording equipment used by civilians are referred to as ?Civilian Monitoring Networks? (CMNs). A CMN may inadvertently record the acoustic signature of NATO submarines, thus compromising their security. To quantify this risk, a computer pro-gram called the Passive Acoustic Modelling Tool (PAMT) is developed to estimate CMN detection range. PAMT uses the Artemis sonar performance model to estimate transmission loss in the vicinity of CMN sensors. Artemis accounts for the effects of bathymetry, sound speed profile, surface and bottom scattering, and bottom conditions. PAMT combines the transmission loss calculation with knowledge of CMN sensor characteristics and ambient noise measurements. The CMN sensor characteristics modelled by PAMT are self-noise and array geometry. PAMT is used to generate maps showing the detection zones for a CMN sensor at a given radiated noise level. The effect of CMN array geometry, frequency, submarine depth, sound speed profile, and ambient noise level is studied.

Capability of the direction of arrival estimation using a 3D acoustic compact array Capability of the direction of arrival estimation using a 3D acoustic compact array

Date added: 02/01/2016
Date modified: 02/01/2016
Filesize: Unknown

Capability of the direction of arrival estimation using a 3D acoustic compact array. Jiang, Yong Min. CMRE-MR-2015-021. December 2015.

The capability of estimating the DOA of underwater source is one of the competencies for an underwater ISR system. A prototype 3DCA was developed underwater glider at CMRE for exploring the capability of estimating the elevation and azimuthal angles of underwater acoustic sources. The 3DCA comprised of eight hydrophones - 3 pairs of hydrophones lie on 3 orthogonal axes, one in the origin, and the other one on the vertical axis. The inter-element separation was 16.5 cm. This layout allows us to obtain up to the second orders of pressure gradient along the two horizontal axes, and up to the third order of pressure gradient in the vertical direction. The spatial resolutions of using the combination of pressure and different orders of pressure gradient were simulated. A relative phase difference based DOA estimation algorithm was deducted for the 3DCA. The performance of the algorithm was evaluated using the data collected during the REP14-MED (Recognized Environmental Picture 2014 - Mediterranean) sea trial, which was conducted to the west of Sardinia in June 2014. The algorithm was applied to the data collected at two acoustic stations with nominal distances of 0.5 and 1.0 km, and at two source depths, i.e. 25 and 60 m, at each station. The algorithm was performed on eight CW (continuous wave) tonals for each source ? receiver combination. The frequency of the signal ranged from 331 Hz to 1433 Hz. It is shown in the preliminary results that consistent estimates of the elevation angle with acceptable standard deviations were obtained. However, a systematic bias in bearing angles was found in the results for every source ? receiver combination and across all the frequencies. Is appears that the 3DCA array structure and the corresponding phase difference DOA estimation algorithm are feasible for being implemented in gliders.

2014 workshop on decision support and risk assessment for asset planning (DeSRAAP 2014) 2014 workshop on decision support and risk assessment for asset planning (DeSRAAP 2014)

Date added: 02/01/2016
Date modified: 02/01/2016
Filesize: Unknown

2014 workshop on decision support and risk assessment for asset planning (DeSRAAP 2014). Vicen Bueno, Raul. CMRE-MR-2015-015. December 2015.

The 2014 Decision Support and Risk Assessment for Asset Planning (DeSRAAP 2014) workshop was organized at NATO STO CMRE to bring together military personnel and research communities to understand and address shortfalls in operational planning aids to assist decision makers. It took place on 9- 11 July 2014 at the NATO STO CMRE facilities in La Spezia, Italy. The workshop focused on understating how the environment conditions the planning and execution of operations in the maritime domain. Several factors and time scales were considered as a consequence: meteorological and oceanographic (METOC) conditions; resources (assets, often limited); as well as socio/economic/political factors. The main objectives of the DeSRAAP 2014 workshop were: Risk assessment; Environmental impact in civilian and military assets (ports, infrastructures, vessels, etc.); Decision support; and Asset planning. A total of 34 military personnel and researchers participated in the DeSRAAP 2014 Workshop. They came from 10 different NATO nations and from 13 different military and research institutions. The presentations provided by each participant are available in a user-password protected NATO STO CMRE server, which can be accessed under request. NATO STO CMRE personnel acquired knowledge of tools/systems on the workshop topics developed by other institutions. An agreement of collaboration between 11 of the 13 organizations participating in the workshop was reached. This agreement is focused on working together on topics relevant to NATO nations, such as: predicting and managing uncertainty; generation of scenarios of potential common interest (counter piracy, illicit activity, irregular migration, oil spill, ice, and coastal areas); and system interoperability.

An unbiased sway estimator for wide aspect synthetic aperture sonar applications An unbiased sway estimator for wide aspect synthetic aperture sonar applications

Date added: 01/25/2016
Date modified: 02/01/2016
Filesize: Unknown

An unbiased sway estimator for wide aspect synthetic aperture sonar applications. Hollett, Reginald D. CMRE-MR-2015-017. January 2016.

In the case of wide aspect synthetic aperture sonar applications, the estimation of sway is subjected to a bias. The bias is taken into account by decomposition into a primary bias an a secondary bias. The performance of the unbiased sway estimator is assessed on the basis of the deviation of estimated values of sway from known values. In the case of sways up to ±1 cm, typical of operational situations, the deviation is found to lie within ±0.1 mm. In the case of a track, the deviation of the estimated position from the known position is found to amount to no more than 2 mm over a distance of 100 m.

CORSAR - a rapidly relocatable ocean forecast system CORSAR - a rapidly relocatable ocean forecast system

Date added: 01/19/2016
Date modified: 01/19/2016
Filesize: Unknown

CORSAR - a rapidly relocatable ocean forecast system. Onken, Reiner. CMRE-MR-2015-011. November 2015.

A prototype of a relocatable real-time ocean operational system named CORSAR, has been successfully implemented for a subregion in the western Mediterranean Sea. The core of CORSAR is ROMS (Regional Ocean Modeling System) which is one-way nested in the global MERCATOR ocean model. At the sea surface, ROMS is driven by the RLM13 atmospheric prediction model, and observational data are assimilated whenever they are available. Since early 2015, CORSAR runs on a daily schedule and provides nowcasts and 72-hours forecasts of the prognostic quantities temperature, salinity, horizontal velocity, and sea surface height. In addition, information about the three-dimensional distributions of potential density and sound speed, the depth of the sound speed minimum and the mixed-layer depth is created from the prognostic variables. The horizontal resolution of CORSAR is about 1.5 km which requires a downscaling factor of about 6 from MERCATOR, and the horizontal resolution of RLM13 is about twice the resolution of the atmospheric prediction model forcing MERCATOR. This enables the evolution of mesoscale and submesoscale features in CORSAR which were not visible in MERCATOR, and more realistic atmosphere driven patterns.

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