Validation of high frequency acoustic target modeling

The underwater acoustics group at TNO Defense, Security and Safety has developed two simulation software programs named ALMOST and SIMONA. The first is already commercially used and aims at sonar performance prediction, whereas the second one is used as a tool to generate simulated data for mine hunting scenarios with the aim to test different algorithms like synthetic aperture sonar (SAS) algorithms or to plan trials. In order to validate targets simulations in both simulators and build a database with detailed acoustic characteristics, different targets were simulated. The targets were a 10 cm diameter steel sphere, a 15 cm long and 10 cm diameter half cylinder (along the length) and a steel exercise manta. The TNO underwater acoustics group basin facility was used to record the acoustic data. The basin is equipped with a scan frame, coated with anechoic material and is 8 meters deep. Each target was measured broadband on a 1D scan for time reasons. The scan frame scenario was then simulated in ALMOST and SIMONA. After some adjustments in the two simulators to take into account the very near field present in the measurements, the visual resemblance with measured data is good for both simulators. Some differences remain that can be explained by the target model used. Herewith, the high frequency target model used in both simulators was validated.