[mythtv-users] Re: New MythTV Hardware Review

Jay R. Ashworth jra at baylink.com
Fri Dec 10 21:52:42 UTC 2004

On Fri, Dec 10, 2004 at 11:52:51AM -0800, Brad Templeton wrote:
> On Fri, Dec 10, 2004 at 10:29:35AM -0500, Joseph A. Caputo wrote:
> > This is how I understand it (from one layman to another):
> > 
> > If you have digital cable, the digital channels (typically channels < 
> > 125 are still analog NTSC, even if you have a digital subscription) use 
> > QAM.  I'm not clear on whether it's the QAM signal itself or the MPEG-2 
> > content that's encrypted (if at all), but in any event the FCC 
> Actually, what I see from comcast is NTSC analog channels, and channels
> 72 and up, plus 33, are QAM transmissions with up to 20 SD channels per
> major channel.  (I was not aware that QAM had so much extra bandwidth.)
> The vast majority are encrypted (yes, it's the mpeg) but a number of
> the locals are in the clear and several are HD.
> In one exception, channel 33-1 is NBC-HD and 33-2 is ESPN-HD.  It's in
> the clear.  The "exception" is both the low channel and the non-OTA
> channel.
> Of course it varies in other cable companies, but from what I see they
> are getting large numbers of SD channels per QAM signal (more than 4
> certainly) and so I presume the entire digital cable lineup is there,
> encrypted, but perhaps I am wrong and other parts of it need to be
> enabled or go in a band my QAM-cable capable TV can't tune.
> Please note I do NOT have digital cable.

I'm confused, Brad.  Cause if you have QAM signals coming in over your
cable, then you have digital cable by definition, no?

Analog cable is comprised entirely of signals which are NTSC RS-170a
system M modulated to be receivable by a standard TV set -- if it can
tune the center frequencies of the channel properly.

It may be the case that you aren't *subscribing* to digital cable...
but that it's on the wire anyway since it hasn't been nececssary for
the cableco to *trap* it to date, since non-cableco, compatible
decoders have been a rare item.

-- jra
Jay R. Ashworth                                                jra at baylink.com
Designer                          Baylink                             RFC 2100
Ashworth & Associates        The Things I Think                        '87 e24
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      If you can read this... thank a system adminstrator.  Or two.  --me

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