19 February 2024

Ukraine’s microphone-laden balloons that battle Russian drones awe US

Christopher McFadden

The United States military is considering developing novel acoustic sensors to counter drone threats, The War Zone reports. Inspired by Ukrainian prototypes currently in use to find and track Russian drones, the sensors could provide a much-needed interim measure before the U.S. planned E-7A "Wedgetail" fleet comes online. Such sensors could provide much-needed early-warning systems to U.S. personnel to defend against long-range kamikaze drones in places like the Middle East.

General James Hecker, who leads the US Air Forces in Europe (USAFE), Air Forces Africa (AFAFRICA), and NATO's Allied Air Command, recently shared information about Ukraine's acoustic sensor network and addressed air and missile defense issues during a press roundtable at this year's Air & Space Forces Association Warfare Symposium.

At the event, Hecker explained how the Ukrainian military has implemented a network comprising thousands of acoustic sensors nationwide to detect and track Russian kamikaze drones.

This network enables them to alert their air defenses in advance and dispatch teams to shoot down the drones. While far more sophisticated, any lover of military history will immediately think about using acoustic mirrors before and during the Second World War.

Before the invention of radar, military air defense forces used these large concrete parabolic passive listening devices called experimental parabolic sound mirrors.

These devices were used as early-warning systems to detect incoming enemy aircraft by listening to the sound of their engines. Hecker went on to explain that the U.S. military is exploring the possibility of testing this capability to enhance its ability to monitor and engage drone threats.

Return of the acoustic mirror

"At the unclassified level, Ukraine's done some pretty sophisticated things to get after [a] persistent ISR [intelligence, surveillance, and reconnaissance]" picture of "low altitude objects," Hecker explained, The War Zones reports. This now includes an acoustic sensor system that utilizes microphones to pick up and amplify ambient noise.

"Think if you have a series of sensors, think of your cell phone, okay, with power to it, so it doesn't die, right? And then you put a microphone to make the acoustics louder of one-way UAVs going overhead," Hecker explained.

"And you have … 6,000 of these things all over the country. They've been successful in [picking] up the one-way UAVs like Shahid 136s and those kinds of things," he added.

Hecker proposed that the acoustic sensor technology detecting drones could have applications beyond NATO. They could be a handy interim measure until more sophisticated ISR assets are online.

Detailed information was not forthcoming, but Hecker mentioned that he is looking forward to delivering "tethered aerostats" equipped with a payload capable of detecting one-way UAVs within the next six months to a year.

These aerostats can remain in the air for an extended period, except during strong winds, when they may need to be reeled down temporarily.

"What it does, you know, when it's airborne, it will give us a persistent picture, ISR picture, down to low altitude, where many of these one-way UAVs and cruise missiles operate at," Hecker said about the E-7A Wedgetail airborne early warning and control aircraft that the Air Force and NATO are in the process of acquiring.

"And it has a pretty good capability in the range that it can detect those [types] of threats," he said.
A novel anti-drone warfare solution

"Unfortunately, they're [the E-7s] not coming off the line starting tomorrow," he continued. "So we have to look for ... interim solutions.," he added. Many modern airborne threats, including small drones, cruise missiles, and stealthy aircraft and missiles, pose significant challenges to current radars.

Given the difficulties in detecting, tracking, and defeating small aerial threats like kamikaze drones for frontline personnel, the kind of "back to the future" use of acoustic listening devices could prove invaluable for the U.S. military. What such systems will look like and how effective they will be is yet to be seen, but this is an interesting proposal nonetheless.

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