Model Development to Support Analysis of Acoustic Buried Target Data

The work reported here makes use of scattering models to understand and develop quantitative predictions for the sub-critical-grazing-angle target detection performance observed in sonar field tests using the Naval Surface Warfare Center Panama City Division’s (NSWCPCD) synthetic aperture sonar (SAS) systems. Recent investigations have confirmed that diffraction of sound into the bottom by surface ripple can greatly enhance the detection of cylindrical targets buried as much as 50 cm in a fairly uniform sand bottom, even when the average grazing angle is low enough (e.g., below the critical grazing angle) and frequencies high enough that detection would normally be expected to be very difficult. Furthermore, evanescent waves provide a mechanism for enhanced detection of buried targets at low frequencies that little quantitative validation has been carried out for. The long-term goal is to identify the mechanism and relevant environmental parameters responsible for detection and use this information to formulate models that reliably predict sonar detection and classification/identification performance against buried mines.