[LINK] US digital tv switch going ahead -- sort of

[Scott Howard]

On Wed, Feb 11, 2009 at 3:43 PM, Jan Whitaker <jwhit at janwhitaker.com> wrote:

> unless things have changed, cable receivers weren't always stbs in
> the US. I seem to recall that I could plug the coax directly into my
> vcr or tv when they were all analog. I *think* here the stbs from the


The vast majority of US analog cable just uses NTSC frequencies.  ie, you
can pretty much just think of the "cable" as going to an antenna and plug it
directly into the back of your TV/VCR/etc as functionally it's exactly the
same.  This is why "stealing your neighbours cable" is so easy - you just
tap the coax and plug it into the back of your TV.

Digital cable is much the same only it uses QAM rather than NTSC, which is
different to over-the-air digital which uses ATSC.  Some TVs can decode QAM
so a cable box isn't required.  However many cable companies actually use
encrypted-QAM in order to reduce the incidence of theft. In that case you'll
need an individual decryptor box and some form of key (smart card or
"over-the-cable" license, etc) in order to decrypt and use the signal.

Even if the QAM signal is unencrypted most people use "cable boxes" for
digital - mainly because only a smaller percentage of digital TVs support it
(they all supporting ATSC for over-the-air), but also in order to access the
extra things like on-demand channels/tv guides/etc which normally require a
specific type of box.

  Scott