Ive been hearing a lot about Multicasting. What is it?
This is somewhat technical in nature, but let me try to explain this… Broadcasters are allowed to transmit up to 19 megabits of data per second for each DTV channel. They are not however, required to use the entire bandwidth for a single channel. Instead, they may split this bandwidth across multiple sub-channels of varying resolution – just so long as they live within the 19 megabit limit. Here where I’m located, the local PBS station broadcasts on channel 21. It’s main channel is 21-1 and it’s a HD broadcast. During the day, they also broadcast on channels 21-2, 21-3, and 21-4. These additional channels are of standard definition. Because standard definition is of lower quality, not as much data needs to be sent over the air and this broadcaster takes advantage of this by broadcasting one HD and three SD channels over the allocated bandwidth. THEN, during the evening hours, channels 21-2, 21-3, & 21-4 are turned off. The extra bandwidth is then allocated to a new channel (21-5) tha
