[mythtv-users] multiple tuner question

[Bruce Markey]

Ray Olszewski wrote:
> At 01:00 PM 6/18/2003 -0500, Richard J. Finn wrote:

> Finally, you may have a mixed system -- analog plus digital. That's what 
> I have, for example, and here I need a digital set-top (actually, it's 
> way too big for "set-top" use) box to get the digital channels (>100, 
> approximately) but can receive the analog channels on any reasonably 
> modern TV, VCR, or video-capture card.

I also use both. The channels below 100 are the same for both
and channels above 100 are only available through the cable
box. I grab listing for two videosources. MythTV doesn't (yet)
have the smarts to know that some stations are the same for
both sources (1030 != 2030) so to avoid confusion, I only grab
the digital cable listings for the high channels. My first
slave (second card) has digital cable into the s-video and
analog cable into the coax. MythTV does have the smarts to
know that it can only use one of these inputs at a time. The
first digital show is recorded from the s-video on the second
card and any other overlapping analog shows go to the other
tuners. If there are no digital shows to record, the second
card gets the second analog show.


> Oh, one closing thought ... with analog cable, each 2-way splitter 
> reduces the signal strength to each connection by about half (-3.x db). 
> Split the signal too much and it starts to look like 1950s broadcast 
> quality. I don't actually know what splitting does to digital quality, 
> but I'd guess that digital is all or nothing ... if the signal is strong 
> enough it is clear, and if it is not there is no picture ... just a 
> guess, though.

Not only will a splitter degrade the split signal but it may
also add interference that may affect the signal from other
cable drops in the house. I use amplified splitters that
you can find at Radio Shack and elsewhere. Some work better
than others.

As for splitting to a digital cable box, analog channels will
be degraded through the box as it is just passing the analog
signal along. For digital channels, there are TCP/IP packets
going over the cable so as long as there aren't data errors,
a weak signal will look indentical to a strong signal. However,
if there is intermittent data loss there would be blocks of
garbage on the screen.

--  bjm