Measurement of sound emission characteristics of quadcopter drones under cruise condition

Quadcopter drones have distinctive sound emission characteristics, which also depend on their mode of operation.
While determining these characteristics is of interest in different contexts, this proves particularly challenging when the mode of operation involves movement of the drone.

In this contribution, a method for characterizing the in-flight sound radiation in terms of sound power and directivity is applied to three different drone configurations flying at different speeds. Based on microphone array measurements, the trajectory of the drone during its flight through the array is reconstructed. The estimated flight path is then used to de-dopplerize the measured signals and determine the directivity based on the time-dependent relative angle of radiation from the drone to the microphones.

The exemplary evaluations include the calculation of sound power spectra and directivity factors. Current limitations of the method are highlighted and ways to overcome them are discussed.