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38 st / July 2014 www.sea-technology.com has continued to de- velop solutions that beneft both the telecom and scien- tifc communities. This overview of undersea telecom tech- nology and currently available transmission and powering architectures is meant to help ocean observatory planners select from new design options available at both the product and architectural level. Acknowledgments We would like to recognize all of the many members of TE SubCom for their product development efforts that support and validate the subsea architectures addressed in this article. We would also like to acknowledge TE SubCom members Bamdad Bakhshi, George Harvey, Maurice Kor- dahi, Lee Richardson and Michael Sanders for their contri- butions to this article. References For a list of references, please contact Robert Thomas at rthomas@subcom.com. n Bob Thomas is with TE SubCom in Eatontown, New, Jersey, where he has sys- tem engineering responsibility for telecom projects serving scientifc and off- shore markets. His undersea cable background includes work in the develop- ment and production of undersea vehicles and in cableship construction. Adnan Akhtar is with TE SubCom where he works on undersea optical transmis- sion design, including modeling, simulation, and optimization of transmission paths for scientifc and offshore platform networks. He graduated with a Ph.D. in electrical engineering from the University of Toronto in 2008. Marsha Spalding is the director of cable and offshore planning and engineering at TE SubCom. She has been responsible for the design and qualifcation of numerous generations of undersea optical fbers and SL cables. Her undersea system experience also includes technical sales, application engineering, and project and product management. Power switched branching units (PSBU) provide un- dersea electrical and optical connections among three cable sec- tions. The electrical con- nections can be switched using optical control signals from a cable station. They can support direct optical connections and shared optical routing through OADM technology. Hybrid Architectures More complex arrangements can be considered, such as multistation observatory powering using a dual-conductor cable, power switched branching units and the high-cur- rent repeater. A hybrid, multiuse system could include an "express" high-capacity telecom backbone used for carrier traffc between shore facilities, with its own conductor and dedicated PFE. High-current repeaters and dual-conductor cable could be employed in selected segments to support observatories, and could be confgured so that each obser- vatory could receive power from either (or both) of the two onshore observatory's dedicated power supplies. The optical connectivity architecture for the same mul- tiuse system includes repeaters confgured with multiple amplifer designs that support different data rates, modula- tion formats and transmission equipment. For instance, at each shore facility, the "express" system would have under- sea telecom grade submarine line terminating equipment (SLTE), and the associated repeaters would have at least one amplifer design that supports this high-capacity DWDM application, i.e., 100 wavelengths x 100 gigabits per second per fber pair. The "observatory" path could use gigabit eth- ernet (GE) and 10 GE transmission equipment in the shore facilities and at the observatories. Conclusion Ocean cabled observatories have multidimensional pow- ering and data transmission needs that differ from standard undersea telecom solutions. Clear-channel EDFA repeaters, high-current repeaters, dual-conductor cables, PSBUs and OADM technology can be used creatively to provide fex- ible data transmission and powering solutions for cabled observatories. The undersea telecom industry has supported a wide range of ocean cabled observatories projects and TE SubCom's Reliance-class vessel, a proven plat- form for cabled ocean observatory installation and maintenance. (Credit: TE SubCom)