[mythtv-users] Different rescanning results from different tuner on same card?

Michael T. Dean mtdean at thirdcontact.com
Sat Aug 25 19:44:12 UTC 2007

On 08/25/2007 11:24 AM, James Cummings wrote:
> On 8/25/07, Michael T. Dean <mtdean at thirdcontact.com> wrote:
>> On 08/25/2007 07:03 AM, James Cummings wrote:
>>> This seems weird to me.  I have a Hauppauge Nova-T dual tuner card.
>>> When I go to the channel editor, delete all channels, and do a rescan
>>> of existing transports on DVB:0 it doesn't find channels on one or two
>>> multiplexes.  If I then go and rescan existing transports on DVB:1 it
>>> *does* find those channels.  I'm wondering if this might explain
>>> recording problems on those channels when the tuner that sees them is
>>> busy recording something else?
>>> Shouldn't both tuners on a single card find the channels just the
>>> same?  Is there some difference between them or something I've set 
>>> wrong?
>> Signal quality affected by the internal splitter or SNR affected by the
>> internal amp (because of poor signal quality)?
> That might make sense.  It is a shared aerial for a 10-apartment block of
> flats.  I've put a powered TV Signal booster on the line to see if that
> helps.  It does boost the signal % myth reports to around 70-75% signal
> while rescanning.

This is probably useful, though, with the configuration described may be
amplifying noise as much as signal.  Ideally, the booster would go as
close to the aerial as possible.  (I have mine 6" from the antenna.)

>   Noise/SNR is always given as zero when I test or when
> rescanning channels.

Yeah.  Some cards' drivers don't report useful values.

>   I'm not allowed to change the aerial/antenna (the
> curtain-twitching little old ladies in surrounding flats will probably
> notice if I sneak onto the roof at night and replace it with one I've
> bought...).


> If that is indeed the problem, any suggestions as to what I can do to help
> it?  Anything else I should check?

Do you have dark close?  Can you get a realistic-looking life-size
picture of the old aerial?  Perhaps your above-mentioned after-dark
aerial installation plan could be made to work.

You may want to first check cables, connections, and ensure you've
terminated any unused outputs of your splitter.  It could just be a
problem with the connections.  If that doesn't pan out, any chance you
have access to an extra single-tuner card to verify that it works with
the cables/etc. even when the good tuner of the current card is
connected (and/or in use)?


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