Acoustic Tags for High Frequency Sidescan Sonar

Abstract

Autonomous underwater vehicles (AUVs) are used by several commercial, research, and military agencies for various applications. To facilitate the navigation of these underwater vehicles, tags and transponders are often used to mark underwater targets or tracks of interest. However, most underwater tag identification systems rely on an active source system and electronic hardware to broadcast a beacon acoustic signal. Such systems require extensive calibration at setup and are prone to high maintenance costs. This thesis work develops lower-cost, totally passive acoustic tags ("AcoustiCode") that are able to encode information which can be read by a conventional high-frequency side-scan SONAR. The AcoustiCode tags utilize Braggs scattering principle to create a unique reflected beampattern (an acoustic signature) that can be detected by a SONAR. The information is encoded in the unique spatial beampattern of each AcoustiCode tag. Numerical simulations and experimental testing in a water tank are conducted to investigate the performance of the proposed approach.