Sky+ And Dual Feed LNB Confusion

[GaryM]

Apologies if this sounds like a dumb question as I don't really know too much about the way LNB's work, but why exactly does a Sky+ box require 2 separate cable feeds from an dual output LNB? Why can the box not take a single cable feed from a single output LNB and then split it internally within the Sky+ box itself, or have it split just before the box (with some kind of "Y" splitter) to avoid 2 cables being run all the way from the dish?

I'm sure my ignorance is probably the main reason but some basic explanation would be welcomed if someone can spare me a few minutes

Thanks.

[penrhyn]

The box has two satellite TV tuners built in to it enabling you to record one channel whist watching another. The LNBs are power fed and individually tuned from the box. Thus the need for twin feeds.
I think there are developments which will allow the use of a single feed from the dish.

[reddwarfcrew]

I could get into the technicalities as you 'could' use a Y splitter, however you wouldn't be able to get all the channels and you;d only get the one's transmitting on the same polarity etc (some transmit on a vertical polarity and some on the horizontal). Part of the sat box function is to send a signal to the LNB telling it to change polarity so that it receives the right channel (it all happens seemlessly to us!!).

Bottom line is that you need 2 feeds from the LNB to be able to use SKY+ properly .

[GaryM]

Thanks for your explanations...understood perfectly

I wasn't sure if it was just a one-way signal from the LNB to the box (like a standard TV aeriel signal) but now I know that the individual tuners in the box talk back to the LNB it makes sense as to why a dual output LNB with 2 separate feeds are required.