Rotation rate estimation of dual propellers drones with opposite direction using a multistatic radar

Accurate estimation of propellers rotation rate is crucial for effective radar classification of drones and provides valuable information into their capabilities. This paper presents two techniques for estimating the rotation direction and rate of two propellers rotating in opposite directions using observations respectively from two and three slightly displaced observation angles. First, leveraging angular diversity, we devise a cancellation technique to suppress the contribution of a single rotating propeller with known period. Then, we employ the derived cancellation technique for estimating the rotation rates and directions of the opposite propellers. The proposed techniques are validated against both synthetic and experimental data, demonstrating promising prospects for the development of drone classification systems.