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www.sea-technology.com March 2015 / st 45 ter, made by Global Ocean Design. The Beacon Board utilizes a GPS re- ceiver inside the UUV glass hous- ing that transmits its position by VHF directly to a hand- held device on the surface ship. An onboard operator is shown a precise range and bearing to the target up to an 8-mile distance, depending on line- of-sight placement of the antenna pair. The UUV antenna may be located inside the glass sphere or external on a fag mast. This method is especially useful in the dark, fog, rain or other limited-visibility conditions. The system is a closed loop between the UUV and the ship: The Beacon Board uses multiuse radio service (MURS), an unli- censed, two-way radio, to transmit its location directly to a receiver on a ship. The shipboard receiver has its own GPS receiver to accurately locate its position. Circuitry inside the receiver decodes the position of the foating UUV, computes the bearing and range from its known position, and displays a compass dial and digital distance read-out to the UUV. A ship's captain can then steer a direct-recovery course. The navigation graphics make clear sense to every mariner and are especially helpful to feld teams operating out of a for- eign port where the ship crew's frst language may not be their own. The addition of an LED strobe provides a visual reference when the ship nears the foating UUV. The hand- held receiver unit can track up to 10 surface targets at one time, logging their transmitted positions for later download to a PC. The handheld receiver can also accept navigational charts. Tests of multiple confgurations have been made off- shore San Diego with good result. Conclusion Several means for determining position of a low-profle UUV on the surface are available to designers. Some are passive, others alert shore stations, while a third group func- tions to communicate with the surface support vessel and dynamically aid in the location of the UUV. Each beacon has comparative strengths and weaknesses, and a designer can select the options that best match his mission profle. n Kevin Hardy founded Global Ocean Design in 2011, following retirement from the Scripps Institution of Oceanography, where he developed and deployed deep-ocean landers around the world, including numerous ocean trenches. He was personally recruited by James Cameron to join his DEEPSEA CHALLENGE Expedition to the Marianas Trench. Hardy is a fellow in the Marine Technology Society. He can be reached at kevin@globaloceandesign.com. Brock Rosenthal founded Ocean Innovations (La Jolla, California) in 1993 to help guide customers though the sometimes bewildering array of marine tech- nology products. He enjoys the challenge of fnding the optimal solution for every technical problem, given the temporal and fscal constraints. Rosenthal is a fellow in the Marine Technology Society. He can be reached at brock@o- vations.com. A foating UUV, lying low at the sur- face, radios its GPS position directly to a nearby recovery vessel up to 8 miles away with a Global Ocean Design Bea- con Board.