Environment Adaptation for LFAS and Corresponding 3D Modelling of Sonar Performance

In Anti-Submarine Warfare (ASW), focus has been shifted towards littoral environments. These harsh environments are in general characterised by high variability in sonar performance, depending heavily on environmental input-parameters. Therefore, a strong need is signalled for accurate sonar performance models, which can model range-dependent as well as bearing-dependent behaviour of Low Frequency Active Sonar (LFAS). These models in turn should provide the optimal sonar parameters setting (e.g. optimal depth and optimal use of available frequency bandwidth). In this paper an example will be given of this kind of modelling and optimisation. The TNO-FEL model ALMOST (Acoustical Loss Model for Operational Studies and Tasks) is used as a kernel, controlled by a research software tool, in order to combine sonar performance calculations for multiple bearings and multiple sonar parameters. Simulation results are compared with LFAS measurements. It is concluded that the 3D model seems adequate to predict the sonar performance, even in difficult environments, but that there is still a long way to go before automated optimisation of LFAS settings is reality.