Under ice positioning and communications for unmanned vehicles

Unmanned "gliders" have demonstrated long endurance operations and are the platform of choice for broad scale meteorology and oceanography (METOC). With buoyancy engines, gliders can operate for months and have demonstrated success with common oceanographic sensors. Likewise low frequency acoustics have been used for basin scale tomography for many years. Together these technologies present a comprehensive tool for under-ice operations. Low frequency acoustics show promise as a method to locate undersea vehicles. This is especially valuable in the arctic environment where ice cover prohibits routine surfacing for GPS fixes. The overall capabilities of this combined system are presented in this paper. This paper builds upon demonstrated results in under-ice and open water environments to present a systematic vision of future capabilities. While the entire system, as discussed, has not been fielded under-ice, the component capabilities have been proven in field programs. Emerging technologies will improve the concept. The primary application will be navigation and telemetry for unmanned vehicles operating in ice covered waters. With effective navigation and telemetry, the demonstrated long endurance of unmanned gliders can be applied to regional environmental monitoring and offshore operational needs in the arctic and Antarctic. Underwater acoustic systems can provide geo-location and telemetry in ice-covered regions. Broadband sound sources with precision clocks can provide underwater navigation in the Arctic, with frequency and signals selected for the ranges of interest, which span tens to thousands of kilometres. Initial experiments in the Fram Strait in 2010 have shown the utility of the single-tube source for transmitting long-range communications and navigation signals. This paper presents results from these trials, and others, and assess the potential performance of a combined glider/acoustic system for under ice environmental monitoring.