"Commercial websites currently exist that display in real time the tracks of relatively high and fast aircraft—from small general aviation planes to large airliners—all overlaid on geographical maps as they fly around the country and the world," DARPA's program manager Jeff Krolik said. "We want a similar capability for identifying and tracking slower, low-flying unmanned aerial systems, particularly in urban environments."
While the FAA is using much more consumer-friendly burrito delivery tests to build out a method of low-altitude air traffic control, DARPA envisions a system that can be used by the military in urban settings overseas or for homeland security applications in the US. DARPA's plan would include a network of surveillance nodes that can track slow, low-flying drones without the need for a direct line of sight. Those nodes could be anything from a fixed instrument to a tethered or "long endurance" drone and the whole thing is meant to be cost-effective and highly scalable for larger coverage areas.
While the agency doesn't have a plan for implementing this dragnet just yet, the program is seeking proposals from teams with "expertise in sensors, signal processing, and networked autonomy." Full details about the project goals have been posted to FedBizOps and there is a Proposers Day scheduled for September 26th, 2016 in Arlington, Virginia.