[mythtv-users] Hauppauge WinTV-quadHD TV Tuner Card 1609 and Pixelation

Allen Edwards allen.p.edwards at gmail.com
Tue Feb 19 19:56:09 UTC 2019

On Tue, Feb 19, 2019 at 10:32 AM Barry Martin <barry3martin at gmail.com>

> Hi Allen!
> You can pretty much make the sensitivity of all of the tuners irrelevant
> with a preamp right at the antenna.
> Yes, agree: the best tuner in the world is only as good as the signal to
> it. Here have experimented with a few pre-amps within three feet of the
> antenna’s connector, different splitters (non-amplifed), etc. The problem
> seems to be a drop of the signal due to wind or possibly movement of tree
> branches. I can’t cut the neighbours’ (plural) trees but can move the
> antenna and that didn’t help. And the pixellation occurred if too
> deep/length of a signal; drop, never with an increase, so presuming not an
> overload and therefore cutoff of the tuner’s AGC circuitry or possibly
> overloading of the splitter. (And I’m stating as partially as what I have
> done to rectify as opposed to being confrontational – I’ll admit I may be
> on the wrong track and willing to listen.)
> As it seems like the only thing I haven’t changed and have control over is
> the tuners I’m considering a newer tuner might have better acceptance of
> signal strength variations.
> Barry

Given everything you have said I would say that there are two
possibilities. One is the loss of signal strength you are suspecting. In
that case a higher gain antenna might help.  Unlikely that a better tuner
would help as you have tried amplifiers and report no change (I think you
said that).

The other thing you might be seeing is multipath or direct signal fading
which can certainly show up more when there is wind as the tuner cannot
adapt to the change in multipath or signal level fast enough.  In this case
a new tuner might help if the new chip is better at dealing with fast
changes in the signal characteristics. In this case it is more the DSP and
AGC part you are concerned with and less with the RF sensitivity.  Here a
higher gain antenna can also help as the beam is narrow and the antenna
itself will reject the interfering signal.  If you are experiencing signal
strength fluctuation in the signal path from the wind, you need a chip that
has a fast AGC and can deal with fast changes in signal level.  So given
all this, I have to confess I have no idea what the state of the designs
is.  If it were me, I would want to know what demodulator was in the tuner
and look at the claims in the datasheet from the chip manufacturer. Also,
see how new or old the chip is. I think that the demodulator is likely more
important than the tuner in this case.


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