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brk-lnt · 02-06-2012, 04:22 PM

If the cable system is acting like a "giant antenna" then something is seriously wrong with the system.

Most modern cable systems use a dynamic channel frequency mapping. On your cable box it may always say that Channel 123 is NBC-HD for example, but the cable box is remotely programmed to make Channel 123 correspond to different frequencies. This can happen for a number of reasons, one of which could be allocating bandwidth for cable modem usage. Cable modems "steal" bandwidth/frequency from what can be used to carry TV, so there is a constant tradeoff/balance to be had.

About 8 years when the systems were first going digital, and digital tuners were not very common, many of the on-demand shows were just mapped to upper frequencies. You'd watch The Sopranos on-demand, and the cable head-end would make the equivalent of Channel 1000 for your request and tell your cable box to tune that frequency (even though it would look like you were still on channel 1 or channel 99 or whatever). During these times you could see what your neighbors ("neighbors" being people on the same node as you, not just your street) were watching by scanning these upper channels with a QAM tuner card. You'd also see them pause/rewind/fast-forward as well, since all that happens at the head-end. In many cases you can still do this in hotel room cable systems if you have a laptop and a USB tuner card for instance.

Anyway, not sure why TWC changed the channel mappings, but it was probably for some relatively uninteresting reason.

02-06-2012, 04:22 PM	#2
brk-lnt Senior Member Join Date: Aug 2007 Location: South Down Shores Posts: 1,939 Thanks: 535 Thanked 568 Times in 334 Posts	If the cable system is acting like a "giant antenna" then something is seriously wrong with the system. Most modern cable systems use a dynamic channel frequency mapping. On your cable box it may always say that Channel 123 is NBC-HD for example, but the cable box is remotely programmed to make Channel 123 correspond to different frequencies. This can happen for a number of reasons, one of which could be allocating bandwidth for cable modem usage. Cable modems "steal" bandwidth/frequency from what can be used to carry TV, so there is a constant tradeoff/balance to be had. About 8 years when the systems were first going digital, and digital tuners were not very common, many of the on-demand shows were just mapped to upper frequencies. You'd watch The Sopranos on-demand, and the cable head-end would make the equivalent of Channel 1000 for your request and tell your cable box to tune that frequency (even though it would look like you were still on channel 1 or channel 99 or whatever). During these times you could see what your neighbors ("neighbors" being people on the same node as you, not just your street) were watching by scanning these upper channels with a QAM tuner card. You'd also see them pause/rewind/fast-forward as well, since all that happens at the head-end. In many cases you can still do this in hotel room cable systems if you have a laptop and a USB tuner card for instance. Anyway, not sure why TWC changed the channel mappings, but it was probably for some relatively uninteresting reason. __________________ [insert witty phrase here]