Recently while driving down Interstate 485 my detector kept reporting activity every time I was near an overpass. A RADAR DRONE! Yup, some agencies place cheap radar emitters near the highway to set off an alarm. Not sure if I would call it a true false alarm. This has been going on for a while now, but it seems their use is increasing. I would even say that their use in construction zones is a good idea to help slow people down.
Ok, arguments about how truly useful these are aside, here are a few ways that detectors help to deal with drones and other false alerts.
If you have a radar detector with a multi threat display such as the Bel Professional Series RX65 or Escort Passport 8500 X50 Black and you drive in an area with drones, you will be alerted if police are also nearby and trying to use the drones to hide their radar signal.
Some of these drones use an uncommon frequency, such as X band, and can be safely manually filtered. Many radar detectors such as the Bel STi Driver radar detector also display the specific band frequency, and will help to differentiate between the band the drone uses and actual police radar.
So add drones to the list of things that will set off a detector (door openers, radar cruise control sensors, etc...)