@anarchosaurus Ah, Tchaikovsky. I've heard it's got some really good reviews. Must find the time to read it

@anarchosaurus @cypnk I read this before the parent post, didn't realise it was about artificial satellites and wondered what was notable about that.

@woozle @cypnk There are some electronics in the dish that are related to the channel you're tuned to. It may only be polarization direction, though, so I think two LNBs might be sufficient to power an arbitrary number of receivers with a sufficiently powerful amplifier or a large enough dish. I don't think this is a specific requirement of the satellite TV companies.

@cypnk @woozle All of the access control happens in the receiver itself, so your original post stands if you just replace dish with receiver.

@freakazoid @cypnk Does the tuning hardware have to be in the dish, though? That doesn't really make sense. The dish just focuses a weak signal so an amplifier can pick it up, then the amp sends it to the tuning electronics. ...as I understand it.

@woozle @cypnk For satellite TV the signals are distinguished not just by frequency but by polarization. They're circularly polarized so the same set of frequencies can carry signals with counterclockwise and with clockwise polarization. A single LNB is only capable of picking up one of those at a time. The receiver sends a signal up to the LNB to select which one, but with dual LNBs you can do both.