[mythtv-users] Answers about pcHDTV HD-3000 support in Myth, QAM support, and more

Brandon Beattie brandon+myth at linuxis.us
Wed Oct 20 21:24:59 UTC 2004

On Tue, Oct 19, 2004 at 03:06:27PM -0400, Cory Papenfuss wrote:
> On Tue, 19 Oct 2004, Preston Crow wrote:
> >While the HD-3000 will hopefully have support for unencrypted QAM
> >digital cable streams, am I correct that there is only one coax input,
> >so you won't be able to switch between broadcast and cable in software?
> 	That's an interesting thought.  It doesn't sound all that uncommon 
> to want to tune in some stations via QAM cable, and some via VSB 
> broadcast, but I guess it wouldn't fly.  Of course, what you really are 
> referring to is either a mux'd tuner, or multiple tuners.  You might 
> be able to mix the RF through a VCR's RF output to select between two 
> different inputs.  It would definately be a kludge, though.

It may be possible to switch between QAM and OTA on the fly.  The idea
would be to use a Y-combiner to bring OTA and QAM onto the same cable.
This though could pose major problems.  If 2 channels use the same
frequency you'll obviously have problems.  (I'm not sure but cable may
use higher frequencies???)  There will be a couple seconds of pause
between switching I was told.  Personally, this may be a very ugly hack,
but this is how you would do it.  Otherwise, if you want OTA and QAM,
you will probably be better off having one card for cable and the other
for OTA.  There will probably be a little bit of work to do when QAM
support comes out to set the card into QAM from Myth, shouldn't be bad -
unless it's found you can somehow be safe pulling OTA and QAM feeds in
over the same cable to the card.  

As for having a second coax input that would be a mute point since there
is only 1 tuner in the card.

> >Personally, I would have kept the two coax inputs and dropped NTSC input
> >altogether.  All the reports from the forums suggests that hardly anyone
> >is even trying to use the NTSC side of the card, as using a hardware
> >MPEG encoder is vastly superior.
> >
> 	It's not that simple.  Although I don't know for sure, I suspect 
> that the two RF inputs on the HD2k were for TV and FM-radio, not TV1 and 
> TV2.  Getting the smaller form-factor and possibly cheaper tuner on the 
> new card were probably a factor.

The HD-2000 card had one coax input for ATSC and the other was for NTSC.
Both used the same tuner though.  This was somewhat helpful if you
wanted to use NTSC with your current home antenna, but you had to buy
another directional antenna for HD.  NTSC and ATSC towers aren't always
in the same place so antenna location may only work well for 1 broadcast

I do not know why the HD-3000 is different.  


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