Distributed network of underwater sensors based on local time-frequency coherence analysis

Underwater acoustic sensor networks are an important element in a large number of applications such as surveillance, environment monitoring...The development of an autonomous sensor system imposes the distribution of the data processing at the level of sensors. This operation is subject to a trade-off between the processing efficiency and the algorithmic complexity that influences the power consumption. In the case of current networks, a common way to answer to this trade-off issue is to process data (detection, recording, transmission...) when the energy of the observed signal, in an arbitrary analysis window, exceeds a given threshold. In this paper, we propose an underwater network configuration that is composed of sensors implementing a different processing approach, based on the hypothesis of a local time-frequency coherence (FM sweep). The results obtained on real data illustrate the efficiency of this algorithm, in terms of signal´s characterization and lower communication bit rates.