[mythtv-users] Please help!

[Robert Denier]

On Tue, 2005-09-13 at 23:48 -0400, Tony Paterra wrote:
> Michael,

Well I'm obviously not michael, but perhaps I can help.

> What would be the effect of changing my setup to connect my digital
> cable STB to the PVR-350 using S-video instead of having the separate
> tuner connection?

The key words here are "digital cable S(et)T(op)B(ox)" or more
specifically digital.  If many of your cables channels are digitally
compressed, then it is also reasonable to assume that those channels are
compressed with a high enough bit rate to be signficantly better than a
pure analog transmission.  Also, if the digital version is the only way
to get those channels then you obviously need to use the digital cable
box...

Why is this important?  Well if it was a pure analog cable system you
would probably be better off just to split the signal from the cable
company and connect it to the 350 and be done with it.  Note that I said
probably, since it is possible the tuner inside your 350 isn't as good
as the one inside the digital set top box, but I doubt that is an issue.
As a side note, if you can do it, I'd suggest leaving a blank card slot
between your 350 and other cards, since this might reduce interference a
little.

Basically if you have digital channels I'd use the s-video cable from
the digital tuner like you said.  If you have only analog channels I'd
stick with it plugged in direct.  Better yet, you can simply try both
without it taking really that long...

>   I'm guessing this will send a much cleaner signal
> to the PVR that it would be less susceptible to interference than
> hunting down the cable companies line and putting better cabling and a

Usually cable companies have enough gain on a line to be split several
times.  (Too much gain, can occasionally make things worse from what
I've seen.)  The other email mentioned quality coax and the rest.
Basically, if your making your own cables, get a good quality RG-6 coax
and ends, and the correct tool (that can be $30ish).  In general, if you
can do it, you should have one splitter from the main cable line, then
each coax going to a separate tv.  You should try to choose a splitter
with only as many outputs as you are going to use.

If you have say 2 - 30 foot coaxial runs and one 5 foot run, you may
want to leave an extra 10 foot or so coax on the short run to balance
things a little, but it usually won't matter.  If you split it more than
about three ways you might need the amplifier you mentioned, but again
circumstances vary.

> booster as close as I can.  The only thing left to do would figure out
> how to link up the remotes (I've seen recommendations for either a
> serial cable or an IR blaster).  

Well if your cable box has a serial port and can be controlled via
serial then that is the way to go, otherwise it would be an IR blaster..

> Sorry my background doesn't include a
> strong physics/EE education, does this stand to reason?

I have a PhD in EE ;)  Of course, I used almost none of what I learned
there to answer this email.  I suppose, if I was really bored I could
try to look at it from a signals prospective, but I rather suspect it
would be an afternoons work and not change much.

As one final note for people distributing video to a lot of tv's and
such.  If you have an older house, it may be useful to check the
electrical wiring in the house where the tv's are, at least if strange
things are happening that can't be explained other ways.  In my own
house we found a ground wire was missing causing there to be some
current traveling down the shield on a coaxial cable that went to a
television downstairs.  It wasn't much current but it measured around 60
volts on a meter and caused a dish network satellite switch not to work.

-Robert