[Bo102010]

Your edit isn't quite correct - if 100 people in the same building (service group) are watching the same TV channel, there's no bandwidth savings if they're all getting an individual stream. See (http://en.wikipedia.org/wiki/Switched_digital_video) for an example of a hybrid approach.

Also, there are already technologies that know what TVs are displaying.

[pasbesoin]

Thanks for the response. I'm still a bit fuzzy this morning, and I think I was conflating a few things.

I think:

~ They want to get rid of the existing "basic cable" distribution. Which is still analog. Digital signals consume less bandwidth, don't they? So, if you are knocking off relatively few basic/analog subscribers on a segment (the rest are already digital), you can more from the elimination of the analog signals -- even though they are "shared" -- than you lose to the additional digital signals. (All the more so if those viewers don't often view TV, e.g. with Comcast those who have "basic cable" because their pricing models essentially make it "free" when you subscribe for residential internet service.)

~ In going all-digital for TV, by not putting the basic channels or some subset on clear QAM (instead, everything is encrypted), they don't need a physical presence to enable/disable TV service -- even for "basic cable". You get a box in the mail, or you have a smart enough / new enough TV, and then upstream controls whether or not you can decrypt.

~ As for my "FCC" comment, as I somewhat poorly understand it, as part off the "digital conversion" negotiations, cable TV companies agreed to maintain the "status quo" until... I believe sometime in 2013, was the date finally settled upon.

But they've pushed the boundary. In my area, forcing everything above an ever-shrinking channel set of "basic cable" to be digital, with digitally switched (if "free", in limited quantities) set top boxes required. So, your old VCR or DVD recorder or perhaps some older models of Tivo (don't know, don't have one) no longer work fully in that they can't pick the TV channel. They're dependent upon this digital box and only get whatever one channel it is manually set to output.

I'm one of those people who has "basic cable" basically because of the Internet pricing. My parents had "extended basic", but found themselves forced to upgrade because these "freebie" digital boxes meant that e.g. the Tivo stopped working.

Now they pay more, and have some POS Comcast DVR all because Comcast was allowed to skirt the edges (exceed, in spirit if not in (re)interpreted letter, in my opinion) of this "it stays the same for cable customers until 2013" agreement.

[Bo102010]

FWIW, basic cable isn't analog (well, some channels can be delivered in analog), so your points based on that line of thinking don't follow. It's typically not switched-digital because the basic services (such as the major broadcasters) are heavily watched, so there's not much benefit to going to switched-digital.

[pasbesoin]

Ok. But here, basic cable is still analog -- as my nice but rather old Panasonic 27" can attest.

My parents had extended basic. My father's understanding was that Comcast's mandate that they switch to a free, deck-of-cards sized set top box, and/or rent a Comcast DVR, meant in part that the digital signals being delivered are switched. Perhaps that's switched for smaller viewer share, and multicast for those channels with heavy viewership -- that's what I understand you to be saying.

This week's been my week to repeatedly reveal myself for the fool I am. So, I might as well make a thorough job of it in this thread.

P.S. As I recall, his thinking was in part that to keep the "deck of cards" transceiver small, power efficient, and cost effective enough, it must be receiving a single switched signal rather than trying to handle multiple signals. But perhaps it is picking amongst multiple signals, but only handling one of then at a time. (So, e.g. not producing multiple outputs that would enable a old Tivo to keep working.)

Sorry if this subthread is going on too long.

P.S. Thanks again for the explanations/clarifications.

[Bo102010]

Glad to help inform!

It's generally accurate to say that basic cable isn't _switched_ digital, which isn't the same as saying it's analog.

It's not accurate to say that basic cable is analog - that is, a single channel can fit into a 6 MHz space. Some providers may put their whole basic lineup in analog, but this is decidedly not a technical requirement.

There's a difference between the little Comcast DTA (for receiving clear QAM digital signals that aren't switched) and a tuning adapter (for receiving digital signals that are switched).

For my company, some markets have no analog channels at all - basic cable services are delivered as clear QAM, and customers use a QAM TV, a DTA, or set-top box to receive them.

Other markets have some analog channels and some digital channels as part of basic cable - if you have an analog TV, you can only see the analog ones, unless you have a DTA.