DJI sells a product called Aeroscope which is an antenna platform used by airport towers; it shows them via the frequencies the drones operate on where the drone is, that it is active, all information tied to the serial number including the drone pilot's FAA registration (who the owner of the drone is, the pilot's phone number, their address, etc.) It also this shows them the location of the pilot via the remote control frequency.

This applies even for their sub-$1000 consumer drones, and FAA registration is mandatory for all drones above 250g weight.