AC3 is digital encoded sound used in a stereo system.
PBS runs several shows at the same time but you need an additional device to decode it, otherwise you hear nothing. The satellite receiver sends out the sound portion as an optical signal. Some people use a stereo system to decode this, others use Extigy, others use their computer. Yet they are the same shows shown in different time zones. Nevertheless, you can get PBS with sound from Montana PBS. Its great. I even joined their membership and in return I get a monthly TV guide detailing their programming. Since there is a 2 hours time difference (I'm in Eastern time zone, while Montana PBS is Mountain time zone), I use my VCR to tape what I want to watch.
