I've been thinking of upgrading to a Hopper but wanted to understand how Primetime Anytime (PTA) actually works. It is my understanding that one of the hopper's tuners records all four networks during primetime hours. How does this actually happen? Are all four networks "multicast" and encoded on one transponder and the Hopper then splits them all up on its end? If that's the case then which transponder is it on and which satellite? I'm on the western arc.