Sunday, December 17, 2017
      CMRE Facebook page  CMRE LinkedIn page  CMRE PAO Youtube page
   
Text Size
CMRE banner

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. 

Documents

Order by : Name | Date | Hits [ Ascendant ]

Multipath pulse shapes with refraction Multipath pulse shapes with refraction

Date added: 04/01/2006
Date modified: 06/22/2012
Filesize: Unknown

Multipath pulse shapes with refraction. NURC-FR-2006-005. April 2006.

All long range sonars have to contend with the effects of multipath propagation. One effect is that an impulse from a remote source or a reflected impulse from a point-like target will be significantly broadened. For example, in isovelocity water it has already been shown that one expects the tail of the pulse to fall off linearly in dBs with a decay constant that depends only on the bottom reflection properties and does not depend on the range of the target. Furthermore if neither sonar nor target have significant vertical directionality then the pulse shape is independent of their properties too. This finding has important implications for the design of sonars since integration times need to be matched to the characteristic arrivals of a target in its environment. The benefit of analytical solutions is that behaviour becomes immediately clear without having to cover an ndimensional parameter space. In addition one can make generalisations which would otherwise be impossible. This report extends the work to investigate the effects of upward or downward refraction. The known angle behaviour of the multipath arrivals can be converted into a time dependence to reveal the multipath pulse shape for a remote source (one-way path) or a target (two-way path). Exact solutions can be calculated numerically, explicit closed-form approximations are given for oneway paths, and these are converted to two-way paths by numerical convolution.

Modern minehunting techniques and the MCM EXPERT software Modern minehunting techniques and the MCM EXPERT software

Date added: 04/01/2006
Date modified: 06/22/2012
Filesize: Unknown

Modern minehunting techniques and the MCM EXPERT software. NURC-FR-2006-011. April 2006.

Side-scan sonars are increasingly being used to perform detection and classification in minehunting operations. The current NATO Mine Countermeasures (MCM) software tool, MCM EXPERT, provides support for the planning and evaluation of minehunting operations, but was developed for MCM units having forward-looking sonar. The NATO Undersea Research Centre (NURC) has initiated a project to provide the capability to accurately plan and evaluate minehunting operations using side-scan sonars and Autonomous Underwater Vehicles (AUVs). As part of this project, a complete review of the MCM EXPERT algorithms was undertaken in order to evaluate their applicability to modern minehunting systems using AUVs and side-scan sonars. Based on a review of the current algorithms, the NURC have provided a set of interim recommendations for the use of MCM EXPERT with side-scan sonars. Certain pre-conditions, which have been documented in this report, must be met for MCM EXPERT to be used to plan and evaluate minehunting missions using side-scan sonars. In addition, limitations in the accuracy of the results obtained when using MCM EXPERT for side-scan sonar are stated.

Algorithms for Decision Aid for Risk Evaluation (DARE) version 2.1 Algorithms for Decision Aid for Risk Evaluation (DARE) version 2.1

Date added: 04/01/2006
Date modified: 06/22/2012
Filesize: Unknown

Algorithms for Decision Aid for Risk Evaluation (DARE) version 2.1. NURC-FR-2006-002. April 2006.

Decision Aid for Risk Evaluation (DARE) is a software tool for assessing the risk to transiting vessels after Maritime Mine Countermeasures (MCM) have taken place. The DARE software has been used in NATO Exercises since 1997. The software has been updated and improved to reflect the needs of the NATO navies. In order to estimate the risk to naval traffic, DARE uses information on the mines countered during MCM Operations, along with the "percentage clearance," or the probability estimate of having countered any given mine. DARE is a command level tool developed to provide an estimate of risk in the case where there may be several units working together and where the mine threat cannot be attributed to a single mine type. Another NATO software tool, MCM EXPERT, can be used to assist units in Planning and Evaluating tasks, and to provide the percentage clearances required by DARE. The NATO Undersea Research Centre has been responsible for the previous two versions of DARE. Version 2.0, released in May 2004, was entirely revised from the previous release (DARE98) and included a new Graphical User Interface, an updated algorithm, and an optimized calculation method which greatly increased the size of scenarios that could be calculated. DARE version 2.1 was released in December 2005. In addition to new software functionality, this version has additional algorithms which can be used to handle the case of multiple transitors. This document provides a comprehensive treatment of the algorithms used in DARE version 2.1.

Active detection performance sensitivity to target depth and aspect changes in a shallow water environment Active detection performance sensitivity to target depth and aspect changes in a shallow water environment

Date added: 04/01/2006
Date modified: 06/22/2012
Filesize: Unknown

Active detection performance sensitivity to target depth and aspect changes in a shallow water environment. NURC-FR-2006-006 / SR-433. April 2006.

The variations on the performance of LFAS systems in coastal areas due to target depth and aspect are examined. The analysis is based on real data acquired during the BASE ’02 sea trial conducted using NURC’s LFAS system and a conventional submarine as cooperative target. Three structured scenarios and one free play are considered. The structured cases include: a) single depth change, b) three moderate aspect changes due to zigzag manoeuvering associated with three target depth changes, one for each aspect, and c) multiple depth and aspect changes due to target manoeuvering in conjunction with abrupt source depth changes. The free play, with only depth constraints, demonstrated the challenges of detection in the littoral when target manoeuvering enjoys many degrees of freedom.

Infrared detection of marine mammals Infrared detection of marine mammals

Date added: 12/01/2005
Date modified: 08/14/2012
Filesize: 1.72 MB

Infrared detection of marine mammals. Alberto Baldacci ; Michael Carron ; Nicola Portunato. SR-443. December 2005.

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 (MLJX'03) that took place in August-September 2003 onboard the NRV Alliance. The test investigated the potential IR technology for marine mammal detection, in both day time and night time conditions. The effectiveness of this IR system in detecting marine mammals was strongly affected by weather conditions, ranging from excellent performance during clear and low sea-state conditions to poor performance during hazy conditions or higher sea-states. The IR system was tested during both day and night.

User Login