Sea Technology

MAR 2017

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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14 st / March 2017 major ports and harbors. These linked up to the internet, encouraging the development of third-party vessel tracking platforms that allowed anyone with a Web browser to view all commercial vessels within range. The big breakthrough around 15 years ago was the unexpected discovery that AIS signals could be picked up by low-orbit satellites at ranges 10 times greater than at sea level. This marked the dawn of near-global AIS coverage. As satellite operators continued to add compact AIS packages to their platforms it became easier to track vessels even in midocean, and so AIS came of age as a vessel tracking system whose basic service could be adapted for a wide range of purposes and users. Of course, AIS is not the only, or indeed rst, satellite tracking system. A wide range of maritime satellite-based A IS has come a long way in the two decades since it be- came an indispensable feature of maritime life. Its origi- nal purpose, which is still an important part of its functional- ity today, was as a ship-to-ship collision avoidance system. This it achieves by using VHF signals to continuously transmit a ship's GPS position, which can then be received by other vessels within range using AIS transponders and displayed on electronic charting systems. Associated software can then analyze the distance, course and speed to ascertain if there is any risk. Additional information regarding each vessel's iden- tity, speci cations, cargo and routing can also be packaged within the VHF signal. Over time, a network of shore stations, both profession- al and amateur, developed around the world, starting with AIS Essential for Fleet Management, Security Satellite Tracking Goes Well Beyond Collision Avoidance #Z4UFWF+POFTt.BSL)FXJTIt,FWJO+POFT The Notices to Mariners feature displays all current warnings and notications as used by national and international maritime authori- ties. A single click reveals the details for each.

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