Experimental demonstration of passive acoustic identification tags for AUV localization and wireless backscatter communication

Accurate positioning is critical for autonomous underwater vehicles (AUVs), particularly during homing and docking. Passive Acoustic Identification (AID) tags offer a scalable, cost-effective alternative to active acoustic and optical methods, excelling in turbid and cluttered environments. These tags guide AUVs by generating distinct acoustic signatures to improve localization and navigation accuracy. This study demonstrates long-range experiments with larger AID tags (up to 24-inch diameter) in a lake environment, tested at frequencies between 100 and 600 kHz. Results show detectability at distances exceeding tens of meters, with optimized signal processing techniques enhancing robustness in cluttered conditions. Furthermore, an active tag design for wireless backscatter communication was implemented. Powered by ultrasonic energy transfer from an interrogating AUV, the tag harvests energy and communicates data via single-frequency modulation, achieving data rates of up to 200 kb/s even in low signal-to-noise environments. These advancements establish AID tags as a dual-purposesolution for improving AUV localization and enabling robust communication in complex underwater missions.