[mythtvnz] Possibly dying tuner card? (or something else?)

[Stephen Worthington]

On Sun, 06 Jul 2014 12:20:39 +1200, you wrote:

>Hi All,
>
>I've been running my Myth setup for nearly 3 years pretty successfully,
>but recently I've been running into a lot of problems with failed
>recordings. This started out with almost all recordings on the
>MediaWorks multiplex failing, but it has since started occasionally on
>the other multiplexes too. From looking at the logs this looks like the
>adapter is unable to tune and eventually gives up. This appears to be
>more likely when another recording is already in progress. I've done a
>couple of retunes whilst this has been going on, but they didn't help.
>
>In the last week we have also started to get a lot of interferance on
>some recordings. Last night this produced a recording which was
>completely unwatchable due to picture degradation and sound blips.
>
>Looking in the log for this recording came up with something
>interesting:
>
>Jul  5 19:25:05 laforge  mythbackend[2881]: W DVBRead
>dtvrecorder.cpp:1290 (ProcessTSPacket) DTVRec(7): PID 0x3ec
>discontinuity detected (( 5+1)%16!= 7) 0.57985%
>
>This message is repeated 42677 times for this recording! Which fits with
>the almost constant picture issues. Aside from that myth completed the
>recording 'successfully', athough another recording which started later
>failed.
> 
>Since the hardware and software didn't change since this was working,
>I'm wondering if this is caused by a slow failure of the TV tuner card,
>or some other part of the receiver setup (which consists of maybe 10m of
>cable to the antenna and a Kingray amplifier [with phantom power
>injected from ground level]). The other option is some real interferance
>- there is a ham radio operator in the next street who I've always
>suspected.
>
>The relevant details of my system are as follows:
>
>OS: Debian Wheezy with deb-multimedia packages for myth, etc.
>Tuner Card: Hauppauge HVR2200
>MythTV Version: 0.26.1+fixes20140227-dmo1
>
>I've uploaded the log from last nights recordings at
>http://webworxshop.com/~robert/logs/mythbackend.log.20140705. The
>recording 'Midsomer Murders' was the corrupted one, whilst the recording
>'Knowing' failed to tune.
>
>I'm going to try and do some investigation with tzap later today and I'll
>post the results here.
>
>Please let me know what you guys think.
>
>Thanks in advance,
>
>Rob Connolly

When one mux is giving problems, or gives more problems than the
others, that usually indicates reception problems, rather than tuner
problems (unless, like me, you have muxes forced to use specific
tuners).  Usually one mux has the worst signal, either the lowest
power transmitter, or the highest frequency.  So that mux is the one
that gives problems first.

I would suspect the cabling first.  Are you using good shielded aerial
cable (RG6 I think is what is best), and F-connectors everywhere you
can?  Is there somewhere that another power or signal cable has been
installed or moved to that runs parallel near your aerial cable?  Has
a cable been bumped and pulled out partially anywhere (eg while
vacuuming)?

Check that the power supply to your aerial amplifier is still working
- they are usually just wall warts and hence not usually the most
reliable of things.  Visually check that the aerial itself is OK and
still pointing in the correct direction.

Try using LiveTV and see what the on-screen signal level and s/n
values show, or use dvbtune.  This is the command line I use for
dvbtune:

  dvbtune -f $a -qam 64 -gi 16 -cr 3_4 -bw 8 -tm 8 -m -c $ADAPTER

where $a is the frequency in kHz (530000, 562000, 578000 or 594000 for
Wharite), and $ADAPTER is the adapter number, which is 0 or 1 in your
case.

Do you have another DVB-T tuner you could plug in for comparison (eg
USB one on your laptop)?