"Surveillance drones" are small flying machines equipped with cameras and sensors that are used to watch and monitor people or places from above, collecting information and capturing images or videos. Full definition
They may also keep a solar - powered surveillance drone in the sky for what could be years at a time. (scientificamerican.com)
Thus, in the summer of 2013, the news of the «rise and fall» of a German surveillance drone caught the German and European public by surprise. (blog.politics.ox.ac.uk)
It is light enough to be carried by these tiny surveillance drones and also uses very little power. (newscientist.com)