Defence
Gunfire Noise Analysis - GNAT
The CAS Gunfire Noise Analysis Tool (GNAT) models the propagation and attenuation of gun and shell noise and displays calculated noise level contours over a digitised terrain map.
The GNAT software model uses the prevailing weather conditions and digital terrain data along with measured noise spectra of guns and shells to establish propagation paths and associated attenuation. Using the calculated results it plots noise level contours and calculates noise power levels for key areas of inhabitation.
The system is being used by the UK Ministry of Defence in the planning phase - to establish the likelihood of increased levels of noise nuisance to the introduction of new guns at the Otterburn live firing range in England - and at Salisbury Plain to actively manage noise.
The Otterburn Range lies in a National park area and the environmental impact of noise pollution is of key concern to all inhabitants and visitors to the area.
Use of the system at Salisbury Plain has led to a noticeable reduction in the number of noise related complains.
The GNAT model takes into account a number of factors which contribute to, and influence, noise propagation and attenuation. These factors include :
- Geometric spreading
- Directivity
- Barrier Attenuation
- Air Absorption
- Wind and Temperature
- Ground Attenuation
Wind speed, direction, temperature and relative humidity are all important factors governing noise propagation. The CAS GNAT offers simple dialogue boxes to allow evaluation from current or expected meteorological conditions. Results may be displayed as calculated noise level contours over a map or as tables.
GNAT has facilities to set up a number of different scenarios concurrently and switch between them. All scenarios can be saved to disk for later recall and analysis. Map data can be supplied for any area and is, essentially an array of digital terrain elevations.
The system software runs on a standard desktop PC and has been designed with ease of use in mind.