Jacob, I looked for some documentation on the 12 mile range but can't find it just now. I do know it works though. When spraying our furtherest farm I always forget to change towers. I use to always get a warning of being too far away from base station, I had to switch towers. Now I can go and spray there without having to switch towers. It's 11 miles away from it.

 edit: I found the page.

http://www.deere.com/en_US/newsroom/2007/releases/farmersandranchers/082307_starfire.html