The US Navy is using drones to gather data that could help improve radar and communication at sea.
Unmanned aerial vehicles (UAVs) can easily fly into parts of the atmosphere where weather variations can alter the path of radio waves, increasing the chance of enemy interception or of radar systems missing potential targets.
The UAVs collect real-time measurements of variations in atmospheric and ocean conditions that provide a detailed picture of the turbulence that affects radio waves, which could enable engineers to design communication systems that compensate.
‘In the old days, we launched weather balloons to give us the best data on the real environment, but that only happened in one place and at one time of day,’ said Commander Rob Witzleb, head of capabilities and requirements for naval oceanography.
‘Many miles and hours later, we were often left looking for answers when weapon systems didn’t perform the way we thought they would. Using UAVs is giant leap forward in that they can give us near-continuous data, across multiple parameters where the atmosphere is the most unpredictable.’
Changes in the lower atmosphere can cause radio waves to be refracted in different ways, sometimes trapping them in “ducts” that allow the signals to travel much further than under normal conditions.
This makes the transmissions more likely to be intercepted by an enemy and can prevent radar systems from receiving the reflected signals they use to detect objects.
‘We need to understand where we are in relation to this ducting environment and understand the energy we’re emitting and the energy an adversary is emitting,’ said Dr. Dan Eleuterio, program officer for ONR’s Ocean Battlespace Sensing Department.
‘If we don’t know these things, it’s like rolling the dice. If we do know them, it can give us a tactical advantage.’
The Office of Naval Research (ONR) vessel Knorr recently spent a week sending out ScanEagles – the low-cost, long-endurance surveillance UAVs built by Boeing and used by navies around the world since 2005 – to collect data about the ducts, flying as low as 100 feet (30m) above the ocean surface.
The ScanEagles carried sensor packages developed by the Marine Physical Laboratory at Scripps Institution of Oceanography that measured surface waves, winds, humidity and temperature to fluxes in mass, momentum and energy.