This paper reports on early observation results from the S-band Array for Bistatic Electromagnetic Ranging Technology Demonstrator Array. This system is a demonstration platform for a passive ground-based primary radar station for monitoring aircraft. This station is unique in that it utilizes existing satellite-based radio signals as transmitters rather than terrestrial signals. Using algorithms that enable long integration times, this system might provide accurate position and velocity measurements at ranges of tens of nautical miles from the ground station for most targets, and up to 100 nautical miles for larger targets. In these measurements, XM-Radio was used as the illuminator and the SABER-TDA station as the receiver. Different types of aircraft were observed in different scattering geometries. Comparison with truth data is in progress.

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Autonomous underwater gliders are a family of autonomous vehicles used for a long-range, long-term observation of oceanic environments. To do this, they leverage changes in net buoyancy and the resulting vertical motion to generate forward locomotion via hydrodynamic surfaces. To function for extended periods, these systems operate in a low-speed, low-drag regime. Conventionally propelled underwater vehicles typically operate at speeds in excess of those achievable by gliders and therefore require more energy in order to compensate for losses due to hydrodynamic drag. An interesting question arises when considering the operational efficiencies of conventionally propelled systems when they operate at speeds typical of underwater gliders. A first-principles energy-based approach to glider operations was derived and verified using real-world data. The energy usage for buoyancy-driven propulsion was compared to conventional propulsion types. The results from these calculations indicate that a conventionally propelled autonomous underwater vehicle can compete with a buoyancy-driven system given the proper propulsive efficiency.

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