Sea Technology

NOV 2018

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

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Navigation

Page 29 of 52

www.sea-technology.com November 2018 | ST 29 at sea; and eth2 (192.168.40.1/24) is plugged into the WAN2, which connects to the internet via 4G rout- er (192.168.40.2/24) when the ves- sel is in port or near the coast within coverage of a mobile network. The UTM firewall must be con- figured to cover all network man- agement needs. Satellite internet is expensive, and the bandwidth is small. The firewall's primary job is to allow only a few computers to connect to the internet; otherwise, navigation would be extremely slow or impossible. The RV García del Cid has a bandwidth of 128 to 256 kbps, lim- iting internet access to five comput- ers. To communicate via text, the WhatsApp application can be used on smartphones; this requires min- imal bandwidth. The smartphones are connected to the access point "ap-whatsapp" (192.168.4.47/32). The access point has an activated DHCP that gives each smartphone an IP address in another range. To ensure that only text messages are transmitted (no images or videos), a service is configured that permits only traffic from 192.168.4.47 via TCP/UDP port 5222, which is used by the application to send text mes- sages. To establish a VPN between the vessel and UTM-CSIC headquar- ters, it is necessary to have a Zentyal at each site. The UTM-CSIC manag- es several research vessels, and a star structure was designed for their VPN. Each ship's Zentyal is connect- ed to the headquarters' Zentyal. In this way, people obtain access from the vessel (range 192.168.4.0/24) to the headquarters (range Public IP- UTM/25) and vice versa all within the same network. The ship's Zen- tyal (192.168.4.1) is the gateway. The DNS server resolves the names of all fixed machines con- nected to the ship's LAN. The DHCP server gives the machines an IP ad- dress between 192.168.4.100 and 192.168.4.199. Satcom at Work In May 2018, the RV García del Cid was involved in the data vali- dation project of the Surface Water Ocean Topography (SWOT) sat- ellite in the Balearic Sea. SWOT is a NASA project that aims to ac- complish the first global survey of Earth's surface water. The work that the Spanish RV participated in was called PRE-SWOT, during which the in-situ data collected by the ves- sel was compared with data from NASA airplanes. Satcom was used to provide internet access and telephone ser- vices to those involved in PRE- SWOT; to coordinate the operations with the UTM-CSIC headquarters; and to send the data in real time. This field work proved that the new vessel satcom system enables and manages communications at sea. Acknowledgments This work was performed in sup- port of the European Union, co-fi- nanced by the European Regional Development Fund. The authors would like to thank UTM Director Jordi Sorribas and the captain of RV García del Cid, Ale- jandro Muro, for their help. ST Alberto Hernandez works for the ICT department of UTM- CSIC to develop and improve communi- cations systems for research vessels and Antarctic stations. He holds a B.S. in tele- communications en- gineering from Alcala University and an M.S. in free software from Open Catalonia University. Raul Bardaji is in- volved in internation- al projects related to developing and innovating autono- mous observation platforms. He has specialized in DIY technology and data analysis tools. He holds a B.S. and M.S. in telecommunications engineering from La Sal- le, Ramon Llull University. Juan Luis Ruiz is a data manager at UTM-CSIC and is involved in interna- tional projects related to distributed marine data infrastructure. He holds a B.S. in electronics engineer- ing from Barcelona University. find out more www.blueprintsubsea.com enquiries@blueprintsubsea.com sound by design Multibeam Imaging Sonars Single and Dual Frequency Operation Portable Sidescan Sonars Towed, OEM, Hull and Pole Mounted Micro-USBL Tracking Beacons Bidirectional Acoustic Data Modems

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