How do local channels on satellite TV work?
Your local signals really do come in via the satellite but are delivered by spot-beaming. The antennas are aimed at particular parts of the country, allowing the broadcaster to reuse the same frequencies for more than one set of local channels. It could well be that these signals are stronger because the antennas are more directional, which would explain why you could continue picking up your locals during the storm. In some areas you need an oval dish that can pick up two satellites to get your channels; they do use that second satellite for locals and they also use spot-beaming there.
Kindall’s got it for the locals. For other channels there is a different explanation. For DirecTV it’s just transponders that are weak or the FEC is set wrong. Hey, you try living in space for a decade and see if parts don’t start to go bad! 😀 Each transponder can easily carry 5 – 20 channels, depending on the quality wanted. Providers are able to change the FEC rate (Foward Error Correction). A low FEC (1/2) means half the data is error correction, making the signal easier to receive after correction. A high FEC (7/8) means 1/8 the data is error correction, making the signal harder to receive after correction. The tradeoff with FEC is data rates. A typical transponder runs at about 20 Msym after viterbi correction (another required error correction), so at 1/2 FEC the provider transmits 10 Msym of usable data. At 7/8 FEC the provider can transmit 17.5 Msym of usable data. Satellite providers
