Detection of multiple micro‐drones via cadence velocity diagram analysis

Many studies have demonstrated the capability of radar micro‐Doppler signature for classifying micro‐drones. However, most existing works on radar classification of drones are based on the assumption that the received signal is only reflected from a single drone. When multiple drones are present simultaneously, the existing methods of drone classification fail due to the superimposition of the micro‐Doppler features of multiple drones. In this Letter, a method for detection of multiple drones is proposed. First the time–frequency spectrogram is converted into the cadence‐velocity diagram (CVD), which expresses how the curves in the time‐frequency‐domain repeat. Then the cadence frequency spectrum (CFS), as the basis vector of the training data from each class, of the CVD is extracted. Finally, the K‐means classifier is used to recognise the component of multiple micro‐drones based on the CFS. The experimental results on real radar data demonstrate that the proposed method is capable of dealing with multiple drones with satisfactory classification accuracy.