The Pentagon’s research entity and BAE Systems are working together to develop a next-generation undersea drone communications technology to help identify mines, find enemy submarines and surveil many items relevant to combat missions.
Using underwater acoustic signals, a surface buoy, beacon or “node,” and GPS signals in a coordinated fashion, the Positioning System for Deep Ocean Navigation (POSYDON) is able to quickly relay location coordinates from undersea drones on patrol to command and control systems on board a ship or submarine.
Distant Thunder / NetSAT littoral water system (DARPA)