Shallow-water low-frequency active sonar modelling issues

Developing models to predict the detection performance of low frequency active sonars requires consideration of each of the parameters in the traditional sonar equation. In many cases, it may be desirable to investigate and develop models that produce high fidelity estimates of parameters such as total reverberation energy. With each of the sonar-equation parameters, there are some fundamental modelling issues: for the purpose at hand, would ray theory, normal-mode theory, or yet another approach be appropriate? Is it acceptable to model only range-independent environments, N/spl times/2D environments, or is it necessary to model fully 3D varying environments? Furthermore, requirements on output products, graphical user interfaces (GUI), and availability of environmental information must be considered. This paper gives an overview of the issues in developing such models with examples drawn from DREA's Shallow Water Active-sonar Modelling Initiative (SWAMI).