Long-Endurance Maritime Surveillance with Ocean Glider Networks

This study examines the integration of ocean glider Unmanned Surface Vehicles (USVs) and Unmanned Undersea Vehicles (UUVs) in support of wide-area oceanographic and acoustic sampling. These collaborative systems could enable the U.S. Navy to conduct multi-month unmanned maritime surveillance. Optimal sensor position in the water column and persistence are critical requirements to reduce surface expressions of such a network. An experiment was conducted in Monterey Bay to evaluate underwater gliders as mobile passive acoustic sensing platforms. Acoustic propagation modeling was used to plan experiment geometry, predict transmission loss (TL), and estimate acoustic communications performance with a USV. A medium frequency acoustic source was deployed at a range of 5.5 km from a receiver on board a glider conducting a 1000 m dive to demonstrate that a glider can adapt to the local environment to exploit more reliable propagation paths. Results demonstrate that gliders are effective mobile platforms to support persistent acoustic sensing. The glider received transmitted signals at levels in close agreement with TL predictions. Signals were received while the glider was in motion, and reception improved during a quiet deep loiter. Given the depths, ranges, and environmental conditions studied, research and modeling suggest sufficient acoustic communication performance to promote connectivity of the proposed network.