Re: A bit more on that pesky drone.
If we can hear it, it's not impossible for them to hear it.
Unfortunately, an RPV must constantly feedback information to its controllers, so it cannot be totally stealthy. It is emitting radiation, cleverly and sneakily, but sooner or later people will figure out how to crack Enigma. They always have. Maybe that's not how they got this one, but if they're smart, we'll never know for sure.