Performance evaluation of C-UAS sensor systems and the development of detection algorithms require ground truth knowledge of the position of the target drone to be available during the measurement. In practice this is done by retrieving flight logs from the UAS, and comparing the obtained GNSS positions with the known position and orientation of the sensor at the corresponding timestamps in the recorded sensor data. Alternatively, video or sensor data can be manually annotated by an operator to indicate whether a drone is seen in each frame, allowing sensor performance to be evaluated.