Bidirectional acoustic tag for marine biotelemetry, system design and implementation

This paper proposes and introduces the design and implementation of a novel bidirectional acoustic tag (BTAG) for marine biotelemetry, enabling enhanced tracking and data collection from aquatic species. Unlike conventional unidirectional tags, the BTAG supports bidirectional communication, allowing for precise time-of-flight (ToF) measurements and improved geolocation accuracy. This system reduces deployment costs and the post-processing complexity while ensuring compatibility with existing acoustic telemetry networks. The BTAG employs ultra-low power components with a 1-year bidirectional life and a 10-year unidirectional mode, with a miniaturised footprint of 50 mm in length and 17 mm in diameter, and a tailored piezoelectric transducer, achieving operational longevity despite its miniaturised form factor. Field and laboratory tests demonstrate its performance, achieving effective transmission ranges up to 250 meters at 80 % reception rate, and optimal reception capabilities such as 70 meters at sea, with 90 meters tested in freshwater. The system holds the potential for integration with autonomous vehicles, further advancing marine research and conservation applications.