Drones knocked out of the air by sound waves

Sound waves resonating at a certain frequency can knock a drone out of the air, researchers have found. By focussing on the gyroscope component of drones, scientists from the Korea Advanced Institute of Science and Technology were able to force consumer UAVs out of the sky.

Micro-Electro-Mechanical Systems (MEMS) gyroscopes are used within drones to provide balance and stability while airborne. Experiments showed that these gyroscopes can be manipulated with external sound frequencies to disrupt their operation.

Findings from the study, Rocking Drones with Intentional Sound Noise on Gyroscopic Sensors, are set to be presented at the USENIX Security Symposium in Washington this week. "We first tested 15 kinds of MEMS gyroscopes against sound noise and discovered the resonant frequencies of seven MEMS gyroscopes by scanning the frequencies under 30kHz using a consumer-grade speaker," the study states.

"We performed real-world experiments and a software simulation to verify the effect of the crafted gyroscope output. Our real-world experiments showed that in all 20 trials, one of two target drones equipped with vulnerable gyroscopes lost control and crashed shortly after we started our attack."

Initial experiments focussed on rendering a drone inoperable by attaching a speaker to the drone itself. The researchers said that major weapons manufacturers would be able to develop a tracking system that could direct sounds at a drone from a distance.

"We found in these experiments that an attacker with only 30% of the amplitude of the maximum sound noise could achieve almost the same effect at the same distance. The countermeasures that are mentioned in the last subsection have limitations and require hardware modifications and additional materials," the paper concluded.

Due to the increase in production costs that hardware modifications would entail, the researchers suggest a low-cost, software-based defence mechanism to prevent against such attacks in the future.