The design and performance of a compact underwater acoustic network node

A major focus of the Acoustic Telemetry Group at Woods Hole Oceanographic Institution (WHOI) has been the development of underwater acoustic communication networks. Similar to a cellular telephone network, an acoustic network consists of a number of nodes or modems which adaptively route digital data packets between scientific sensors and a data collection or viewing point. A significant milestone in the development of such a network has been the recent demonstration of a multichannel adaptive receiver for coherent underwater communications. As the current generation of commercial telemetry devices do not meet the computational requirements of this algorithm, a new compact, high-performance modem has been developed at WHOI. This unit has a processing capacity of more than 80 Mflops (million floating-point operations per second) and contains a full-featured personal computer. The capabilities of the new modem are reviewed together with preliminary results from two deployments of a network of six modems. The results highlight the ability of the new modem to autonomously monitor network configuration and channel quality