[mythtvnz] Pixellation Every ~ 20 minutes

[Stephen Worthington]

On Sun, 7 Oct 2012 11:34:33 +1300, you wrote:

>5. For some reason I can't check live signal strength using Alt+F7
>which would help check if this is a signal/lock problem. I might just
>swivel the aerial to Te Aroha instead of Hamilton Infill today, do a
>retune and see if that helps. I used to use Te Aroha previously (well
>before the current issues though).

Going back to first principles here, just how sure are you of your
signal levels?  The last time I had problems like yours, it turned out
that our VHF antenna had come loose in the last gale and turned around
until it was touching the UHF antenna.  That resulted in a loss of
signal strength.  But I did not figure it out until I just happened to
be looking at our roof one day and noticed the misaligned VHF antenna.
All the signal strength and quality readings I was getting from my
tuners said they were OK (or what I thought was OK).  But of course,
each different tuner was reporting different numbers - only identical
models will ever report the same.  What I actually had was marginal
signal levels, and every so often the recording would have a bad
patch, just like you are seeing.  The bad patches, like yours, did not
seem to be occurring randomly - there seemed to be a pattern to when
they happened, so I was looking for other problems initially.

On fixing the VHF antenna, the reported signal levels only went up a
little, but everything was working again.  So the levels before my
problem must have been just on the good side, and during the problem,
just on the bad side, of OK.  Since then, I have added another antenna
amplifier as I have added another tuner to my mother's MythTV box, and
that has boosted the levels way higher.  The VHF antenna has moved
into contact again after more wind, but is not causing any problems so
I am considering just leaving it like that.

So, it might pay to check the antenna, the cables, splitters and
amplifiers, just to make sure.  I have heard of problems caused by the
dog or kids playing or vacuuming over the cables, and them coming just
loose enough to cause problems.  And corrosion is an ever present
danger, although where you are is not close to the sea salt that
virtually guarantees a short life for any TV antenna.