Drones don’t just blow up the enemy | Hindustan Times

In the David and Goliath war between Ukraine and Russia, drones have proved a great equaliser. Ukraine’s short-range aircraft are cutting Russia’s supply lines to its occupying troops, while long-range versions attack oil refineries, airfields and warehouses as far afield as Siberia.

A French gendarmerie drone flies to monitor for wild camping and forest fires around Lake Sainte-Croix, southeastern France on August 8, 2026. (FILE AFP)Not all military drones, however, carry warheads. Many are used instead for spying and target location. A lot of these gather their data at optical or infrared frequencies. But some, involved in the field of signals intelligence, or SIGINT, listen out for radio waves. And within that category are those which seek not to understand what is being broadcast, but merely to identify and locate it, the better to attack it—a field of endeavour that goes by the name of ESM, or electronic support measures.

According to Thomas Withington, an electronic-warfare expert at the Royal United Services Institute, a think-tank, the result has been an arms race in which the radio frequencies used to control drones have migrated ever further up and down the spectrum, in attempts to evade detection. Frequency-hopping radios, which skip from one wavelength to another thousands of times a second, are getting faster, so a transmitter may be visible only momentarily; signals are increasingly disguised to merge into background noise.

Dr Withington notes the advantages drones bring to ESM. A lorry-mounted system with a ten-metre antenna can detect transmitters roughly 13km away. The same receiver on a drone at an altitude of 1,000 metres can see for 130km. Having antennae on drones is also more useful when an attack may come from any direction. It avoids blind spots caused by topography.

The Ukrainians are reluctant to discuss what they are up to. But not all their research is being done in-house. At Eurosatory, a European defence exhibition held in June, Aaronia, a German manufacturer, unveiled a SIGINT electronics package that can be mounted on a drone. The developers say three such drones working in tandem can pinpoint transmitters to within 25 metres from up to 75km away.

At 5kg, Aaronia’s product is inconveniently heavy. Sky Spy, based in Delaware, recently demonstrated Agent 001, a 500-gram electronics package that can be mounted on a small Orqa quadcopter. This proved able to detect, identify and locate “hostile” radios as part of an exercise in Estonia. Agent 001 also has on-board processing, linked to the drone’s camera, so it can move towards a transmitter and capture video for its operator to confirm the identity of the source.

One limitation of small drones, says Dr Withington, is that the amount of processing capacity they can carry is restricted. Such capacity is essential for sifting through signal data. Drone-control signals may, for example, be hidden in Wi-Fi.

New processors and AI software are, however, making small drones vastly more capable. One bit of kit that can be mounted onto a drone, known as Barn Owl, has been developed by NxGenComm of North Carolina. David Gross, NxGenComm’s marketing director, says Barn Owl follows all traffic in the Wi-Fi range, analysing changes to pick out the signatures of concealed military signals. He claims the process is fast enough to keep up with the most nimble frequency-hopping radios, and powerful enough to scan and analyse an 800MHz-wide swathe of radio signals.

Intelligence can go to commanders, or directly to other units. In one proposed set-up, a parliament of Barn Owls would be linked directly to interceptor drones. When they detected an incoming drone, they would launch an interceptor and guide it to the target’s location until it was close enough for visual confirmation by the operator. NxGenComm hopes to deploy Barn Owl to Ukraine in the next few months, and is in discussion with American military customers.

As well as locating enemy drones, ESM can also help identify their control frequencies so that they can be jammed. Both sides get round this by flying some drones via fibre-optic control cables, which unspool as they fly. Such drones, which can carry 50km of fibre, emit no radio signals. Similarly, some AI-enabled drones can operate incommunicado, flying and striking targets without operator input.

In the meantime, however, the vast majority of drones still rely on radio, and the electronic-warfare arms race continues. Falling behind can be disastrous: if an enemy can jam communications and knock drones out of the sky while remaining invisible, heavy losses are sure to result.