Russia’s fiber-optic drones dodge jamming, but Ukraine hunts them with infrared and sound

A thin glass thread trailing behind new Russian drones has neutralized billions in electronic warfare defenses. Now, Ukrainian forces are scrambling to devise new air defense strategies.
A Ukrainian fiber optic drone operator, photo via Ukraine’s Ministry of Defense.
Russia’s fiber-optic drones dodge jamming, but Ukraine hunts them with infrared and sound

Drone warfare is already considered a hallmark of the Russo-Ukrainian war. Drone combat footage has dominated the overall perception of how this war is viewed and will continue to do so in the near future. Doubly so because of the military innovations that are taking place in rapid succession. Quite literally, a “cat and mouse” game is taking place behind the frontlines, with both parties seeking ways to master technology and force a breakthrough on the battlefield.

One such particular case is the fiber optic drone, which has emerged as a notable presence on the battlefield. Even more importantly, as of this moment, Russia has an advantage in this type of drone warfare against Ukraine, having outpaced Ukraine in both development and scaling. Commander-in-chief of the Ukrainian Armed Forces, Oleksandr Syrskyi, noted that Russia’s increased use of fiber optic drones poses significant risks to troop safety and added that Ukraine has also begun deploying similar technology.

The emergence of fiber optic drones represents both a breakthrough and a battlefield puzzle. We’ll examine the engineering behind these systems, their battlefield impact, and how both sides are scrambling to adapt. At stake is not just tactical advantage, but the future direction of unmanned warfare.

The fiber optic drone flying, showcasing the wire attached. Photo via Ukraine's Ministry of Defense.
The fiber optic drone showcases the wire attached. Photo via Ukraine’s Ministry of Defense.

FPV vs. fiber optic – what’s the difference?

The Russo-Ukrainian War sees the large-scale implementation of so-called first-person view (FPV) drones. These small, agile unmanned aerial vehicles (UAVs) are piloted using a live video feed from the drone’s onboard camera, providing operators with a “drone’s-eye view” of the battlefield. FPV drones rely on radio signals for communication.

Initially used for intelligence, surveillance, and reconnaissance missions, FPV drones have evolved into formidable weapons systems. They have routinely been employed as kamikaze units, capable of destroying a wide range of military targets, including armored vehicles, artillery units, air defense systems, and even individual enemy troops.

While standard FPV drones rely on radio signals for communication, making them vulnerable to electronic warfare and jamming, fiber optic drones are controlled through an exceptionally long wire that unravels over several kilometers during flight. This unique feature renders them immune to electronic jamming, basically making them undetectable. Unlike radio-controlled drones, these drones fly at low altitudes, avoiding obstacles and reducing exposure to air defense fire.

The fiber optic drone, photo via Ukraine's Ministry of Defense.
The fiber optic drone, photo via Ukraine’s Ministry of Defense.

The design of these drones is largely similar to conventional combat FPVs, with the key difference being a larger body and more powerful batteries to accommodate a several-kilogram coil of wire that unravels during flight. The smallest drones can operate at distances of up to 2 km, while the largest can reach up to 20 km, depending on the length of the wire attached to the drone. The wire connects to the operator’s control panel and transmits a high-quality image with minimal delay.

The race to detect unjammable drones

As these drones perform well in foggy conditions and are immune to electronic warfare systems, they have become a particular challenge for frontline troops. Although these fiber-optic-controlled drones cannot be detected through their radio signature, there are other methods for detection. Kara Dag, a Ukrainian technology company, has proposed using acoustic and visual signatures combined with advanced processing techniques to detect these tethered drones.

The acoustic detection of drones is a well-established technique that relies on an array of microphones to identify the distinctive noise produced by drone propeller blades and motors. Fiber-optic drones are louder than similar non-tethered drones because their propellers must generate more thrust to support the added payload of the cable spool. Regardless, the primary challenge with this approach has traditionally been range. Noise levels attenuate with distance, and most microphones struggle to distinguish drone noise from ambient sounds at distances greater than approximately 100 meters.

The equipment necessary for operating the fiber optic drone. Photo via Ukraine's Ministry of Defense.
The equipment necessary for operating the fiber optic drone. Photo via Ukraine’s Ministry of Defense.

To address this limitation, arrays of directional microphones are commonly used. These arrays focus on specific portions of the sky, significantly reducing the interference from ambient noise. By sweeping the sky, they can enhance the likelihood of detecting the acoustic presence of a drone.

The visual detection of drones is similarly well-established but also has its own challenges. Small drones often appear as tiny specks against the sky, making them difficult to distinguish from aircraft or birds. Moreover, tethered drones typically fly closer to the ground, which limits the line of sight required for visual detection. However, several proposed techniques use fiber-optic cables to aid in the detection.

Although the cable is thin and difficult to see in the visible spectrum, it reflects light in the infrared range. A drone detection system can exploit this property by using a diffuse infrared laser to sweep the sky and an infrared camera to detect reflections from the cable. The infrared cameras could also detect the heat signature from the drone’s motors as they heat up during operation.

The next frontier in drone warfare

Both acoustic and visual detection methods must identify very small signals within a large amount of noise, the proverbial needle in a haystack. Advances in processing techniques, including machine learning and artificial intelligence, have the potential to make this task easier.

Additionally, when the two detection techniques are combined, they reinforce each other, increasing the likelihood of detecting a drone. Kara Dag is developing such a system for Ukraine, leveraging the country’s strong technical expertise in advanced processing techniques.

The appearance of the fiber optic drone does not imply that earlier drones have suddenly become irrelevant, especially considering the fact that the fiber optic drone has its own downsides:

  • slower than the traditional FPV drone due to cable limitations
  • limited maneuverability due to the adapted size of the drone
  • possible risk of cable snapping
  • requires a larger, stronger frame to accommodate the fiber optic spool and thereby reduces payload capacity for other equipment.

However, this technology is so novel that many issues that currently seem problematic may no longer be an issue as engineers improve the product or as the military learns to use it effectively.

Drone warfare has now developed in such a way that there are general and specialized categories of drones. In effect, every type of drone is specifically built for a certain combat situation. Some drones are more suitable for reconnaissance, whereas others are built for precision strikes on enemy vehicles.

In the most ideal situation, a military unit should have multiple options to its disposal, possessing various types of drones to be used in each particular case. Nonetheless, soldiers often operate in far-from-ideal conditions, to put it lightly. Therefore, the urgent question remains how to counter these particular type of drones.

One such possible counter could come fromlaser technology. In 2024, the British Armed Forces announced that it had successfully tested its DragonFire laser weapon. Laser-directed energy weapons can engage targets at the speed of light and use an intense beam of light to cut through the target, leading to structural failure or more impactful results if a warhead is targeted. DragonFire’s range is classified, but it is a line-of-sight weapon and can engage with any visible target.

The DragonFire laser directed energy weapon (LDEW) system achieved the UK’s first high-power firing of a laser weapon against aerial targets. Photo via Wikimedia.
The DragonFire laser-directed energy weapon (LDEW) system achieved the UK’s first high-power firing of a laser weapon against aerial targets. Photo via Wikimedia.

These types of countermeasures will surely make its impact felt on the battlefield against drones in the future. However, this is still very much research and development, and will not immediately provide an answer on the battlefield in Ukraine.

Currently, neither Ukraine nor Russia has any effective countermeasures against fiber optic drones. Ideas are being explored for physically neutralizing such drones using turrets, net launchers, and shotguns, as well as studying the use of lasers to disable them. As of this writing, the race is still on. Whoever finds a practical and applicable countermeasure first will attain an advantage against the opposing party on the battlefield.

Related:

You could close this page. Or you could join our community and help us produce more materials like this.  We keep our reporting open and accessible to everyone because we believe in the power of free information. This is why our small, cost-effective team depends on the support of readers like you to bring deliver timely news, quality analysis, and on-the-ground reports about Russia's war against Ukraine and Ukraine's struggle to build a democratic society. A little bit goes a long way: for as little as the cost of one cup of coffee a month, you can help build bridges between Ukraine and the rest of the world, plus become a co-creator and vote for topics we should cover next. Become a patron or see other ways to support. Become a Patron!

To suggest a correction or clarification, write to us here

You can also highlight the text and press Ctrl + Enter

Please leave your suggestions or corrections here



    Euromaidan Press

    We are an independent media outlet that relies solely on advertising revenue to sustain itself. We do not endorse or promote any products or services for financial gain. Therefore, we kindly ask for your support by disabling your ad blocker. Your assistance helps us continue providing quality content. Thank you!