Russia and China have been rapidly improving their ability to disrupt American military communications during wartime. Now the US Defense Department is waking up to the problem—and exploring new, harder-to-jam comms systems.
The latest might even be the most innovative so far. The Defense Advanced Research Projects Agency is preparing to test a network of radio relays mounted on sea buoys and connected via hair-thin fiber-optic cable. If the DARPA system works and the Pentagon chooses to acquire it, there could soon come a time when American warplanes swap data via buoys bobbing on the ocean waves.
The jamming problem has been getting worse in recent years. Russian and Chinese forces have deployed increasingly powerful electronic warfare gear in the air, on the ground, and at sea—all aimed at denying the radio frequency, or RF, to the US military.
The Americans are uniquely vulnerable to RF jamming, as many US war-fighting concepts rely on the ability of ground forces, aircraft and warships to exchange information via radio networks.
“We’ve just been assuming that the RF spectrum is a benign environment and nobody’s going to threaten us,” US Air Force general John Hyten, then head of Air Force Space Command, said at an electronic warfare conference in late 2015.
“The rest of the world’s been watching that, too,” Hyten said. “China and Russia in particular.”
To help preserve radio networks in the most electronically-intensive combat, in mid-2014 DARPA launched the Tactical Undersea Network Architectures. “The concept involves deploying RF network node buoys—dropped from aircraft or ships, for example—that would be connected via thin underwater fiber-optic cables,” DARPA stated.
The US government spent around $30 million on TUNA in 2015 and 2016.
TUNA could help US forces to power through electronic interference. Radio signals lose power over distance, making them progressively more vulnerable to jamming. Two jet fighters flying a couple hundred of miles apart and trying to directly exchange data via, for example; a Link-16 network could be particularly susceptible to enemy jammers targeting the Link-16 signal.
But if the first fighter instead communicated with a TUNA buoy a mere 25 miles away and that buoy relayed the data via fiber-optic cable to a second buoy just 25 miles from the second plane, then the distance between emitter and receiver—for both fighters—would be much shorter. The network would be less vulnerable to jamming.
The agency wants a TUNA buoy network to last 30 days—long enough, it believes, for US forces to establish more permanent data networks.
To work as designed, the buoys required two novel technologies. One, an ultra-thin but durable cable “able to withstand the pressure, saltwater and currents of the ocean,” according to John Kamp, DARPA’s TUNA program manager.
Second, DARPA needed some way to power the buoys. Heeding the agency’s call, the University of Washington’s Applied Physics Lab developed a kind of “generator buoy” that produces electricity from wave motion.
Now that the cable and generator buoy are both ready, DARPA announced in January 2017 that TUNA is ready for at-sea testing. American forces are one step closer to communicating through the water and defeating enemy jamming.