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30 st / September 2016 www.sea-technology.com able with high bandwidth and is not limited to short lengths, but comes with higher cost of implementation. This cost includes not only optical wet-mate connectors but also the optical infrastructure required in the electronics module to which the optical connectors are mated. Notable oceanographic projects using optical communi- cation systems include: DONET, Ocean Networks Canada, ANTARES, NEMO, OceaNet, OCB TWERC and MACHO. Ethernet Flying Leads In 2005, Teledyne Oil & Gas (TOG) began develop- ing Ethernet flying leads in response to early adoption of Ethernet by the oceanographic market. Around 2010, demand for Ethernet flying leads increased rapidly due to the standardization of subsea Ethernet by many operators in the oil and gas industry. At this point, it was apparent that the length limitation would eventually be an issue for this market. At that time, the Ethernet flying lead length limit was 60 m before communication broke down and was unusable. In 2011, Teledyne developed a better pas- sive Ethernet solution, which could be utilized reliably for 100-m Ethernet communications. But it was clear that this was still insufficient for applications in which longer distances were required. Active Flying Leads for High-Bandwidth Data Transfer AFL Simplifies Infrastructure for Seafloor Observatories By Michael C. Greene (Top) The Electrical-to-Optical Flying Lead (EOFL). (Bottom) An ROV connects an ODI wet-mateable fiber-optic connector to a subsea instrument plat- form within the NEPTUNE Canada ocean observa- tory network. A s the sensors used in the undersea monitoring net- works environment increase in number and capabil- ity, the corresponding data transmission traffic increases significantly. The data must be collected and transmitted back topside, where they can be reduced and utilized. Traditional methods for data transfer bandwidth include electrical modems, electrical DSL, electrical Controlled Area Network bus (CAN bus), electrical Ethernet, and op- tical Ethernet. Conventional electrical modems can trans- mit data over long distances. This technology is by far the most mature for subsea use, but the maximum data transfer rates achievable are insufficient for technologies that demand data transfer rates in excess of 20 kbps. Where electrical DSL offers higher bandwidth than mo- dem technology at reasonably long distances, the available bandwidth decreases as a function of length and still does not provide enough bandwidth for data-rich technologies (200 to 3,000 kbps, up to 15 km). Electrical Ethernet has proven to be reliable and high bandwidth, but is limited to short step out distances (less than 100 m). Electrical Ethernet is extensively used for short- distance subsea communications. In cases where step out distances are too long, or bandwidth requirements are too great great, optical Ethernet is utilized. Optical Ethernet is reli- optical great, optical Ethernet is utilized. Optical Ethernet is reli- Ethernet great, optical Ethernet is utilized. Optical Ethernet is reli- is great, optical Ethernet is utilized. Optical Ethernet is reli- utilized great, optical Ethernet is utilized. Optical Ethernet is reli- Optical great, optical Ethernet is utilized. Optical Ethernet is reli- Ethernet great, optical Ethernet is utilized. Optical Ethernet is reli- is great, optical Ethernet is utilized. Optical Ethernet is reli- reli great, optical Ethernet is utilized. Optical Ethernet is reli-