Malicious Drone Identification by Vibration Signature Measurement: A Radar-Based Approach

While commercial drones are nowadays effectively used across many application sectors, they can still pose several security risks and, if tampered, may serve as a tool for illegitimate activities. Therefore, it is important to design methods that facilitate the recognition of malicious drones. This paper shows a contactless vibration measurement method that fulfils this task. Indeed, it is demonstrated that the vibration fingerprint of a specific type of propeller can be extracted with a radar sensor. Building upon such a result, a measurement methodology for decoding the vibration signatures of drones is presented as well. In the second part of the work, by controlling variations of the Pulse Width Modulation (PWM) signal driving the drone motors, it is proved that the proposed radar technique can extract a simple PWM codification. Experimental results validate both the methods showing that, by setting up a fixed rotational speed of the propellers, the vibration of the drone chassis measured by the radar allows to discriminate the type of mounted propellers. On the other hand, the radar is also capable of performing such a discrimination of the propeller type, even in the presence of the encoded PWM signal. As the process requires contactless measurements, it will have minimum impact on the operation of the drone while flying or hovering.