Environmental Impact on Variable Depth Sonar (VDS) System Performance

A modeled based performance assessment of the collective acoustic and oceanographic characteristics of the Shallow Water Active Classification SWAC sea trials conducted in the Mediterranean Sea is provided. The assessment enables the determination of which environmental conditions e.g., bottom characteristics and VDS system parameters e.g., source depth significantly impact active sonar system performance for the purpose of identifying system parameters that could be adaptively exploited. Using the best available input data in a range-dependent model. extant conditions throughout four sea tests covering three geographical areas and two seasons were modeled to predict selected performance metrics. Operational performance was then assessed at frequencies near 600 and 3000 Hz to determine a expected variability, b sensitivity to perturbations in the modeled conditions and c the correlation between system and acoustic parameters. In all the SW AC operating areas, bottom loss is the most significant parameter affecting reverberation and SIR. Reverberation, signal to interference ratio and multi path time spread were much more dependent on operating area than time of year. Furthermore, there was as much variability within test events spanning a few hours as was observed across seasons. Results from this assessment will be compared to measured system performance using the SW AC acoustic data at a future date.