Smaller is Better
New technologies provide a lightweight solution for the Navy's communications.
One key component of the Global Security Directorate's research agenda is its work for the U.S. Navy. Heading up this effort is Richard Snead, whose experience as a naval officer, commander of a submarine attack squadron, and Pentagon financial specialist affords rare insight into the Navy's decision process for funding R&D projects. Snead says funding decisions are always contentious and are not always driven by acquiring the latest technology. Some communities within the Navy are concerned that new technologies might not be as reliable as those that have served well for years, while others have a more open attitude toward the potential of R&D. While navigating these organizational dynamics, Snead's job is to match ORNL's comprehensive technology portfolio against gaps in the Department of the Navy's R&D program. "My charter is to represent the laboratory's capabilities in the right places," Snead says. "I find the guys who are interested in whether we can deliver what they need, and then I make sure we deliver."
Laser communication
Among the Navy's varied needs are several that center around signal processing—the ability to transmit, receive and process information. These activities are particularly critical to the ability of unmanned aerial and submersible vehicles to gather and transmit information. One of the obstacles to providing enhanced signals processing capability is the significant power required for communications systems to operate, particularly in unmanned vehicles where weight is at a premium. A related issue is finding the room in the already-crowded radio frequency (RF) portion of the spectrum for the military to transmit information. "Other than fencing off portions of the RF broadcast spectrum for military use," Snead says, "the only place to find free bandwidth is in the visible light portion of the spectrum."
Addressing these challenges is the focus of a team of scientists in the laboratory's Computational Science and Mathematics (CSM) Division led by Yehuda Braiman. Braiman and CSM researcher Bo Liu have found a way to apply some of the very small and inexpensive components normally used to drive industrial lasers to the task of producing high-quality beams for use in communication systems. A critical advantage of these systems is that they are both cost- and energy-efficient, greatly reducing the power required to transmit optical signals. If applied to an orbiting communication satellite, the reduction in size and energy requirements represents the difference between a system that is overhead for 20 minutes of each orbit and one that could maintain a geosynchronous orbit and provide persistent communications coverage over a large area. Snead notes that such a system could enable the Navy to communicate with the entire fleet using a relatively small number of satellites.
Laser-based communication systems also have a critical advantage over RF-based systems when communicating with submarines and other submersible vehicles. Certain laser frequencies can penetrate hundreds of feet of water, enabling relatively high-bandwidth communication links. Current systems require submarines to rise near the surface and raise a radio mast or deploy a communications buoy before sending or receiving information. Snead contends that for submariners a paramount goal is the ability to communicate while moving at speed in deep water. At present a submarine cannot move fast and maintain communications and cannot maintain communications while tracking a ship or submarine. The importance of this breakthrough technology to the submarine force would be a classic game changer. The Navy has been working on similar communication technologies for 30 years, but previous systems were always too big and inefficient. In contrast, the laser source being developed by ORNL is light and energy efficient enough to be mounted on satellites or aircraft, an enabling technology that can be adapted to any number of uses.
Laser-based communication systems hold the promise of constant communication with the entire U.S. submarine fleet using a relatively small number of satellites.
Combining strengths
One adaptation pairs the highly efficient laser technology with ORNL's advanced computational capabilities to create a highly sensitive submarine sensor. The sensor applies the laboratory's computing capacity to the challenge of identifying underwater targets such as submarines and geographical features. Until recently, the algorithms that undergird this approach to signals processing were too complex to be used in a system requiring split-second feedback. Researchers, however, have adapted the algorithms to a new generation of multicore computer processors, enabling the computational load to be shared among a number of processor cores, greatly reducing the time required to generate results.
Multi-core processors, such as GPUs (graphical processing units), have also demonstrated the ability to handle computational loads with greater energy efficiency than that of previous generations of computer chips. Snead believes this unique quality makes GPUs an attractive option for boosting the signals processing performance of unmanned aerial and submarine systems, where currently much of the power must be reserved for propulsion. Snead says ORNL is talking with several contractors about applying GPUs to the problem of energy-intensive signals processing equipment.
Elements of progress
Snead's sponsors are interested in making technologies that are smaller, lighter and more efficient. Part of this emphasis is directed toward increasing the capabilities of unmanned vehicles, while part reflects a constant drive for cost-effectiveness. "The smaller a technology is, generally speaking, the cheaper it is," Snead observes. "Since the Royal Navy built HMS Victory for Horatio Nelson, we have bought innovation by the pound. If it's bigger, it's going to be more expensive." A corollary advantage of downsizing technology is versatility. Snead notes that the Global Security Directorate's Navy sponsors want the ability to launch an unmanned vehicle from a torpedo tube, drop it from an aircraft, or have a team of Navy Seals pick the vehicle up and throw it over the side of a ship. To maximize the potential of unmanned systems, Snead believes future technologies must be small, affordable and adaptable to a variety of launch platforms.
Working from this premise, ORNL is applying a range of capabilities to help the Navy realize a vision of smaller, lighter, more capable and more affordable technologies. Snead's lengthy list of promising research areas includes advanced signals processing; affordable, lightweight materials; power electronics; computation; new welding techniques for thinner pressurized hulls; and advanced robotics for hull inspection and improvised explosive device removal.
Snead is convinced that ORNL matches these capabilities with a commitment to customer satisfaction. "When we get involved with a project, we attempt to prove we can deliver. Recently, one of our sponsors told me that a key difference between ORNL and other contractors is that we tell him how we think things can be done, not why they cannot be done. I am excited that we are making a difference."