[mythtv-users] PVR-150 Tuner Quality Issues

Steven Adeff adeffs.mythtv at gmail.com
Mon Apr 17 12:46:06 UTC 2006


On 4/16/06, Michael Horn <mjhorn at gmail.com> wrote:
>  Thanks everyone for the input so far. I've made some progress with the
> picture quality, through a combination of fine tuning the frequencies as
> well as adjusting some of the brightness,contrast etc settings on the card.
> Ive been adjusting the brightness and whatnot using ivtvctl -y
> brightness=xxx, but it seems that this is reset by mythtv each time the
> channel is changed. are there global or possibly per channel settings within
> myth I should be using instead?

tune to the channel in live TV and set the contrast/brightness/etc
settings you want for that channel. these settings are saved
per-channel in the database and mythbackend uses them when it tunes to
that channel for live tv or recordings.


>  Anyways, the picture is looking much better now, and the only remaining
> problem is of the interference the picture seems to be picking up on some
> channels. Wander, you suggested grounding my case, whats the best way to go
> about this to ensure its properly grounded?

Many surge supresors have a proper ground light indicator that can be
used to see if your outlet is grounded, if so then using the normal 3
wire power cable will give you a proper ground to the computer power
supply, and as long as the power supply is making metal on metal
contact with the case it and the motherboard will be grounded. If your
outlet isn't grounded then you may want to look into getting it
grounded. Its easy enough to do on your own with one of those
self-help books at home depot or get an electrician to do it.

You can also buy a grounding block for your cable (few $$ at Radio
Shack or Home Depot). Or just buy a Home Theatre surge supressor that
has a cable/sat/ant passthrough which will ground and sometimes filter
for noise your cable/sat/antenna. If your using a UPS for your Myth
computer DON'T combine it with a surge supressor! But you can use one
for other equipment in your home theatre and run the cable/sat/ant
through it,

>  And what other sources of interference should I be on the lookout for/ what
> can I do to try and prevent them? I've tried to keep the unit as far from
> the rest of the electronics as possible, including speaker wiring and power
> cables.
if your using proper cables with good insulation those things won't
matter the signal and noise on the lines won't be enough to cross talk
to any meaningful ammount.

>I have a dsl connection, so interference from cable internet isn't
> an issue tho it was a good thought.

again, different frequencies so it won't interfere.

>  Finally I believe the interference is restricted to just my myth box and
> not something picked up elsewhere in the cable line as the rest of the tvs
> in the house show no symptoms.

then its most likely noise from your computer. It could be your
powersupply creating the noise, or even a harddrive or fan within your
case. If you have a good quality powersupply and still get the noise
consider connecting your harddrives and fans to a seperate
powersupply.

--
Steve


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