[mythtv-users] Setting a channel to prefer a tuner or how to remove static

[Bruce Markey]

Chris Moewes-Bystrom wrote:
> I have 2 pvr-150 in my system and for some reason one of them display
> channels 2-4 with static and the other doesn't. I have tried swapping
> the cables and the outputs from the splitter and nothing seems to
> change the quality.

You need an adjustable wrench. Tighten down all the F-connectors
in you home beyond finger tight. Note that interference on one
cable may be the result of a loose connection somewhere else
entirely. Replacing a bad cable in another room may fix the
problem. If you have a splitter with an unused connection, cap
it with a terminator or replace it with a splitter that has the
number of connectors you need.

If there is an open end, the cable can act as an antenna.
If you connected a long cable to your card and left the other
end open, you would likely see ch 4 and possibly even hear audio.
Low channels and some high channels are most susceptible to
this kind of interference.

> So, 2 questions. Any thoughts on why one tuner card would have static
> and the other not?

That's typical. Whenever I have a source of interference, the
effect is different at each drop.

>  I guess I haven't tried switching the pci slot they
> are in but I can't imagine that would be a problem.

If there were interference patterns like diagonal stripes on
several channels then that would be a good idea. Probably
not for interference on low channels but it is worth trying.

> confirm that they are using the same freq's? What might be the cause
> of this problem?

...but this is a dead end =).

> If no answer to the first question, is there a way to make recording
> on those channels prefer one tuner vs the other? I know it is an
> option at the recording level, but is there a way to do this at the
> channel level so I don't always have to remember to set it?

Make sure that the card/input without noticeable interference
is first and the one with interference is last. If this is not
the case, run mythtv-setup and "Delete all capture cards" then
enter your cards and inputs in your new order of preference.
This will not remove your sources and channels. You want to keep
these and only renumber your cards and inputs.

Your "good" card will be used first and if there is only one
recording, only the good card will be used. You could also add
channel priority in TV Settings->Recording Priorities->Channel
Priorities. Add priority to 2-4 so that shows on those channels
are more likely to "win" card 1 when there are two recordings.
I had done this for years due to interference on OLN ch 73 until
channel priorities temporarily stopped working as intended.
This, along with some other needs, led me to add the per rule
preferred input. I could have sent dozens of messages complaining
that someone else should do this as I demand and say that myth
is a bad application by bad people and try to incite other weak
minded people to complain too but I decided to write the code
instead and now it works for me and everyone else too.

You do have a problem that you are going to have to pay attention
to no matter how you cut it. One suggestion that has come up on
this topic in the past is to have a way to disallow channels on
specific inputs but this doesn't work out so well. Say you had
two shows at a time that are both on 'bad' channels. One would
not record due to conflict if these channels weren't allowed on
card 2. You would be better off recording the show even if the
picture isn't as good. If it was unwatchable, you could delete
it but at least you had a chance to see it.

For recurring series, you can set a Channel rule and only set
the prefinput once. Search rules that may match shows on these
channels may still need an override to set the prefinput if
card 2 was chosen. One way to check periodically, is to go
to Schedule Recordings->Search Lists->Channels. Assuming you
have 2, 3 and 4, pick 2 from the popup and look to see that
all the titles in green (or orange depending on theme) are set
to record on card 1 and not 2. Press the "End" key to go to
the list for channel 3 and End again to see ch 4. This should
only take a few second to see if there are any problems for
any of these channel over the next two weeks.

--  bjm