Ukraine employs innovative network: Acoustic sensors for drone defense

General James Hecker is the chief of NATO's Allied Air Force Command and the commander of American air forces in Europe and Africa, otherwise known as the United States Air Forces in Europe - Air Forces Africa. At the recent AFA Warfare Symposium, this American military officer shared a unique approach to combating drones, employed by Ukrainians during warfare.

Reported by The War Zone and quoted by Gen. Hecker, an extensive array of acoustic sensors, created from several thousand stations and utilizing smartphones and directional microphones, operates to aid Ukrainian drone hunters.

Thanks to this vast array of dispersed sensors, it's possible to identify and track numerous objects, including those flying extremely low, to evade radar detection.

A dense network of outposts equipped with acoustic sensors is an effective method for countering such threats as it can detect - even at night - low-flying Russian drones. This is possible because even small drones with weak engines, such as the Shahid-136, generate significant noise.

This enables effective identification of passing objects, determination of their routes, and providing alerts to drone hunters' smartphones. Gen. James Hecker does not specify the exact solutions used by Ukrainians.

However, he mentions that the Telegram platform is a popular communication channel for issuing warnings and coordinating anti-drone tactics. It's commonly used among Ukrainian volunteer drone trackers.

While the media typically focuses on visually impressive weapon types, like the Flakpanzer Gepard or Skynex, General Hecker emphasizes that the foundation of the Ukrainian anti-drone defence system consists of mobile, improvised groups of drone hunters.

They utilize various light vehicles and combat drones primarily with adaptively fitted firearms of different types, like machine guns or - less frequently - small-caliber automatic cannons.

A great example is the use of old-fashioned Maxim machine guns for combating drones, which prove to be an effective weapon due to their high firepower.

Equipment is supplemented with night vision and thermal imaging scopes, laser indicators, and searchlights, enabling the identification and destruction of targets at night.

Ucrainian experiences have highlighted finding the most cost-efficient solutions, thanks to which kamikaze drones can be effectively countered using appropriate tools, without resorting to sophisticated, complex, rare, and costly weapon systems.

Such experiences provide critical knowledge. As Gen. Hecker notes, detailed information about the dispersed network of acoustic sensors has been shared with decision-makers, including those from the U.S. Missile Defense Agency. The objective of this analysis is to determine if and how NATO could use the information gleaned from Ukraine.

Interestingly, the use of microphones or different kinds of acoustic sensors to detect airborne intruders seems like history has come full circle, considering this method was used prior to the advent of radar.

In the early days of aviation development, when locating aircraft flying above a layer of clouds was problematic, sound detection devices were found to be the solution. These took various forms including mobile devices mounted on human heads, larger devices placed on vehicles, up to large, several-yard concrete structures.

Perhaps the most notable example of such a solution is the "sound mirrors" constructed in the UK in the 1920s and 30s.

The creator of this solution, William Sansome Tucker, was a British physicist who was assigned to the Experimental Sound Measurement Station during World War I.

This institution conducted research on sound propagation to develop early counter-battery systems. These were based on registering artillery shots from a network of outposts. The variance in time for each outpost recording the shot allowed the localization of enemy artillery positions.

This system was also adapted to detect incoming aircraft. Beyond various types of mobile listening posts, stationary infrastructure was created. Some facilities like RAF Denge station have survived to this day, forming large concrete structures that reflect and amplify sound waves.

Work on enhancing sound mirrors ceased in the 1930s, when radars gradually replaced listening posts.