Comparative Analysis of Ultra-Low-Power PPM Demodulation Algorithms Applied to Underwater Biotelemetry Systems’ Bidirectional Acoustic Tags

In this article, a comparative analysis of pulse position modulation demodulation algorithms tailored for ultra-low-power applications is presented, specifically in the context of bidirectional acoustic tags developed to improve marine biotelemetry data acquisition. Various algorithms and techniques were evaluated, with the three most theoretically efficient methods tested using a simplified acoustic transmission model and validated against qualitative field data. The two algorithms demonstrating the highest detection performance were subsequently implemented on a bidirectional acoustic tag prototype, where power measurements were conducted to identify the method offering the optimal balance between signal detectability and energy consumption. The results show that the Göertzel algorithm achieves detection performance equivalent to the FFT-based approach while offering significantly improved energy efficiency, operating at a reduced microcontroller clock frequency of 16 MHz, compared to the 24 MHz required by the FFT implementation.