Here's my other video that I just uploaded.
http://www.youtube.com/watch?v=NbNsIljofto
Franklin County sounds for three minute intervals with seven minutes in between. They used to make announcements during the 7 minute periods but they have since stopped seeing as how the siren sounding should be enough of an indication of a tornado.
I was just watching 10tv news and they showed a DUAL TONED 3016 in Franklin County doing alert. I would LOVE to know where that one is!