Originally Posted by JBaumgart
Question: why does Comcast have the same programming on multiple channels? For example, the HD version of HBO is on 215, 300 and 900. Is this really necessary, and is this not a waste of bandwidth?
This is just "channel mapping". In the example listed above, HBO HD is listed in the premium channel area next to the SD counterparts, in the old HD area next to the old HD channels, and in the new HD area next to the new HD numbers. It doesn't affect bandwidth, and is done so for channel surfing, to make it easier to surf.
I'm not sure why they keep the "old" and "new" HD numbering, but I will say that the new HD numbers are the same on both systems (Minneapolis and St Paul). I know at "some point" they are going to remap ALL of the channels to put like-channels together. News in one "neighborhood", general entertainment in another, etc, etc. Then, the HD counterparts are going to be what the SD number is + 1000, so KTCA would be 1002, KSTP would be 1005, etc.
The reason that none of this affects bandwidth is because it is just a simple "map". In other words, when you go to channel 30, the box attached to your TV knows that channel 30 is located at 300Mhz (it probably isn't just using that as illustration). If Comcast wanted to only carry one channel on every number (NBC, haha), then they could just tell the boxes that every channel you turn to is being broadcast at 300Mhz, and it would take up no more bandwidth than one channel. This also allows them to move channels without you knowing about it. So, today, 30 could map to 300Mhz, and tomorrow it could map to 305Mhz, but both times you would just punch in "30" on your remote and get the same programming. Make sense? The same concept applies to HDTV. Channel 2.2 is actually being transmitted on 16, for example. Channel 23.1 is actually 17, etc.