[mythtv-users] PVR-150/500 and bttv?

Joe Votour joevph at yahoo.com
Tue Sep 13 03:18:53 UTC 2005


Greg,

I must say that I'm a software developer, and not a
hardware developer, so I can't say with total
certainty how a PVR-500 actually works.

That said, the set-top box that I was working on has
the same idea as the PVR-500: two tuner chips (the
same chip for both paths), with one coaxial input. 
Therefore, it is a "splitter".  However, I don't think
that it's the same as a regular splitter - I don't
think that you lose 3.5dB, like you would with a
regular two-way splitter.  (I'd have to look at the
schematic and talk with the hardware engineer to be
certain).  Plus, if there was such a high loss, then
the engineers should have compensated for it by
driving up the amp a bit (which is generally done in
the software, and not in the hardware).

I'm sure that the LG tuner part is probably cheaper in
quality than previous parts, but I have a hard time
believing it's that crappy.  I'd believe a bad run
more than that.

BTW, by hand crimping, I suspect that he means the
coaxial connectors that have to be put on and
tightened with a special tool, and are very tight
(i.e. you have to strip down to the copper wire before
putting them on), versus cheaper connectors that stay
in place via soldering or screw-on methods).  There's
definitely a difference between the difference
connector types, we've seen that at the office in the
past (running coax between a CMTS and our cubicles,
for instance).

-- Joe

--- Greg Woods <greg at gregandeva.net> wrote:

> On Mon, 2005-09-12 at 19:28 -0700, Joe Votour wrote:
> > I've read the thread you you mention, and call me
> > skeptical, but I don't buy it 100%.
> 
> Neither did I. I know lots of people who get fine
> reception without
> having to hand-crimp every connection. I am
> skeptical as to how much
> that matters except maybe in a few exceptional
> cases. But I do know just
> from my own experience that the signal degrades when
> splitters are used,
> especially at the end of a long run. The PVR-500
> also has a splitter
> inside it (it must, to the single input to two
> tuners) and is therefore
> more sensitive to signal degradation than is the 150
> (same card, single
> tuner). This is by no means intended as expert
> advice, it is merely what
> I have observed in my particular setup.
> 
> >  I might just
> > have to run a Windows/Linux comparison at some
> point.
> 
> I'm all for scientific experimentation to lend
> credence to or downplay
> theories; that would be an interesting test.
> 
> --Greg
> 
> 
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>
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> 


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