Frazer-Nash Consultancy is at the leading edge of the development and use of naval signature management and assessment technologies. The company supports both surface ship and submarine projects which occupy the complete spectrum of acoustic and non-acoustic signatures.

Working in conjunction with partner organisations, we can provide a comprehensive signature management service which includes signature ranging and measurement. The signatures assessment software used by Frazer-Nash, and described below, can be supplied to those customers who wish to undertake their own signature management and assessment programmes.

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TESAC

TESAC (Target Echo Strength Analysis Code) is a joint development by Frazer-Nash and Thales Communcations UK. This tool enables the prediction of the acoustic target strength of submerged objects such as:

• Submarines
• Torpedoes
• Mines

The code is the result of many years of development effort and the algorithms upon which it has been based have been extensively validated against full-scale and model-scale measurements.

With its easy to use graphical user interface, links to commercial computer aided design (CAD) packages and wide range of result types provided, TESAC provides a comprehensive design tool for TES response characterisation and active sonar stealth.

TESAC uses geometric and physical optics to predict the target strength, incorporating double and triple bounce effects, shadowing of one part of the target by another part, anechoic and other cladding fits, sea bed and sea surface effects. The results can be predicted and displayed for mono-static and bi-static cases and also for synthetic aperture arrays. The tool uses a commercially available 3D model generator (PATRAN) to define the target shape and to produce some of the results displays (overlaying the model with colours to represent the intensity of the reflected signal). Although the tool can accommodate complex target surface acoustic impedances, it does not model target flexibility.

The TESAC software is available for use on UNIX workstations.

IREP

In order to design platforms and weapon systems to specified Infra-Red (IR) targets, a comprehensive IR modelling and assessment package is required. To support all the stages of a platform’s design and development, Frazer-Nash and S&C Thermofluids have developed the state-of-the-art IR modelling and assessment software IREP.

The IREP suite of codes is able to model the combined IR signatures of platforms and their exhaust plumes. These codes have been applied to predict signature data associated with aircraft, missiles, combat vehicles and surface ships. Signature data can be presented pictorially as apparent temperatures or radiances from user specified viewpoints.

An extremely flexible approach has been adopted to the prediction of IR signatures which includes the use of computational fluid dynamics (CFD). The software can predict the IR signatures associated with phenomena as diverse as the aerothermal heating of the leading edges of fast jets and missiles, the IR signatures of their exhaust plumes and those of surface ships. It is driven through an easy-to-use graphical user interface (GUI) and does not require the user to be familiar with fluid dynamics.

Detailed predictions of the interaction of a platform with its exhaust plumes can be very important, particularly with regard to surface ships and land vehicles. In such cases, plumes can lead to heating of local areas of the platform, resulting in radiating hot spots.

The IREP software is available for use on UNIX workstations.

RADSNAT

The RADSNAT (RADiated and Self Noise Assessment Tool) is an integrated software suite that allows the prediction and management of radiated and sonar self noise from submarines. RADSNAT v2 comprises 3 modules covering structure-borne vibration, hull response and radiated noise as well as sonar self noise.

The Structural Response Modeller - Module 1
The structural response modeller is a general purpose vibration modelling code developed by FNC to provide a basis for the prediction of submarine radiated noise.

Radiated Noise Assessment – Module 2
The radiated noise assessment module simulates the response of the hull and the far field radiated noise based on the internal noise sources.

Sonar Self Noise – Module 3
The sonar self noise module is used to assess the effect of different noise sources on, for example, the response of individual hydrophones.

EMAC

EMAC (Electro-Magnetic Analysis Code) is used to predict the radar signatures of a wide variety of platforms and weapon systems. Its general purpose nature ensures that it possesses practical application to:

• Ships and their equipments
• Aircraft and missiles
• Combat vehicles

EMAC provides:

• Comprehensive solvers including physical and geometric optics plus a statistical treatment of rough surfaces
• Models of radar absorbent materials
• Ground plane effects
• Comprehensive output and visualisation facilities (including Synthetic Aperture Radar (SAR) displays)
• An optimising mesh generator
• CAD interface
• Library functions

EMAC has been constructed to be simple to use and computationally efficient to run, thereby ensuring the minimisation of the computer time required to solve a particular problem. Access to the software is achieved using a flexible Graphical User Interface (GUI) which is beneficial to both novice and experienced users. The use of industry standard computer aided engineering packages, such as PATRAN, enables CAD data to be rapidly imported into EMAC and the necessary geometric and electro-magnetic representation of the body prepared with the minimum use of mantime.

EMAC is marketed on a world-wide basis by Frazer-Nash Consultancy and is the result of many years of development effort by Thales Communications UK. Extensive validation trials, at both full and model scales, ensure that a high level of confidence may be placed in the results obtained using EMAC.

The EMAC software is available for use on UNIX workstations.

This product is available for purchase as a complete technology transfer package or it can be used by Frazer-Nash staff on a consultancy basis to provide solutions to specific customer requirements. More detailed product literature is available, together with past conference papers that describe how this software tool has been applied to resolve specific problems.

If you require further information on our products and services, or wish to know if we can assist you in a particular project, please complete the form on the Contact Us page.