Sea Technology

NOV 2013

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

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(Top) A candidate deployment location in San Diego, California. (Bottom) An overview of CONOPS. operators located at a nearby joint operational shore facility. The mobile sensors in this network will usually be autonomous, with operators simply monitoring routine operations. In the event of an anomaly, however, operators can take real-time control of individual platforms, reconfgure the network itself to maximize information fow, extend the sensing range of fxed assets and call in manned intervention if necessary. Importantly, the network will allow for the real-time connection of remote decision makers, even over a great distance, via the Internet. The U.S. Navy's magnetic silencing facility (MSF) in San Diego, California, has been identifed as a candidate deployment location for such a joint system of networked sensors. Concept of Operations A typical concept of operations (CONOPS) for the proposed sensor network would involve several autonomous platforms, each equipped with a user confgurable suite of sensors, autonomously patrolling designated areas, jointly operating with onshore and undersea fxed sensor arrays. A wide range of sensor technologies already exist, such as cameras, hydrophones, nuclear and biological material detectors and environmental sensors. These mobile platforms are connected to each other, to the fxed sensors and to a shore control station over low-bandwidth RF and acoustic communications operating as a mesh network. If one of the mobile or fxed sensors detects an anomaly or emergency condition, a high-bandwidth, secure communications link is established. This high-bandwidth link is a 20 st / November 2013 hybrid FSO/encrypted RF link, in which RF covers outages in the FSO link. However, FSO outages should be minimal because the network will use the diverse positioning of the mobile platforms to continuously reconfgure and optimize itself. An example anomaly would be a Harbor Shield detection of an unusual object attached to the hull of a passing ship. Images of the object would be relayed to a mobile platform on the surface via acoustic communications, and the mobile network would be confgured to provide shore operators a high-bandwidth, secure link between all sensing assets, giving the operators near-real-time eyes on the scene and command and control of the network platforms to better investigate and monitor the developing situation. A beneft of the combined Harbor Shield/ CASMS/WaSPNet approach to harbor and choke-point security and monitoring is that these technologies work in a complementary fashion to address a variety of threat characteristics with high effciency. The fxed Harbor Shield and CASMS sensors—providing both active and passive acoustic cueing—signifcantly increase WaSPNet's on-station availability and longevity by reducing the need of the mobile sensor grid to chase and engage passing vessels merely to perform initial inspections. Platforms on and above the surface of the water represent only part of the needed sensors, so the mobile ad hoc network must be extended below the surface in a useful and reliable manner. A variety of ROVs, tethered and unmanned systems may be used to address the underwater environment in U.S. ports and harbors. As in the surface example, these underwater vehicles will generally operate autonomously, in some cases tethered to an attendant surface platform, and will be connected to the network via low bandwidth acoustic communications. Again, when an anomaly or emergency situation evolves, a high-bandwidth underwater optical network can be established using the surface platforms to give shore operators eyes on the action and near-real-time control of underwater assets. Conclusion Choke-point or perimeter deployment of these systems would signifcantly improve maritime security by enhancing the ability to detect low-observable targets (e.g., selfpropelled semisubmersibles or small submarines), conducting underhull security inspections of vessels in transit and networking multiple undersea and surface sensors through a mobile ad hoc waterborne network. This system would complement existing underwater security installations by using WaSPNet to extend the monitoring range and sensor type of the detection systems. References For a list of references, contact Richard Granger at grang n Nathan Whittenton is a business development manager for L-3 PHOTONICS. Rich Granger is a program manager for Battelle's Maritime Systems business unit. Craig Walker is a lead engineer for the Naval Undersea Warfare Center Detachment in San Diego, California.

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