Here is how they do it in our market (Wilkes-Barre/Scranton). All of Dish's receivers are at WNEP-TV (ABC). There, WNEP sends their signal directly from the tech area to DISH. THe other stations are picked up with off air antennas, with the option to fiber the signal to the plant. There the output is combined and sent on fiber to an uplink site, which I believe is in NJ. DirecTV is similar, except the receivers are at WVIA (PBS)