[mythtv-users] USA recommendations for Digital Over the AirCapture Card

[David Brodbeck]

On Wed, November 19, 2008 2:48 pm, Kevin J. Cummings wrote:
> ATSC = DTV  It includes the 8VSB currently being used OTA *AND* the
> 16VSB and QAMs currently being used by cable companies (see the
> wikipedia page for ATSC).  So, saying that it can do both ATSC an QAM is
> redundant since QAM is a part of ATSC.

To clarify further, 8VSB, 16VSB, and QAM are all modulation methods --
they describe how the digital signal is converted into something that can
be transmitted over the air or over coaxial cable.  In the U.S., 8VSB is
used for over-the-air broadcasts; and 16VSB and QAM are used for cable TV,
with QAM being the more popular of the two.  (Analog TV only had one
modulation method -- VSB.)  I'm not going to go into what the letters mean
because it's all very technical and there's frankly not much reason for an
end user to care.

The distinction is useful because not all tuners can handle all of these
modulation methods.  For example, most set-top converter boxes can only
receive 8VSB, because they're intended for receiving over-the-air
broadcasts.  They don't do QAM, so if you hook one up to cable you won't
get anything.

Actually, QAM isn't even part of the ATSC standard (yet), but cable
operators don't have to follow any particular standards if they don't want
to.

Is it any wonder consumers find digital TV so confusing?