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

[Stephen Worthington]

On Mon, 07 Jul 2014 21:31:44 +1200, you wrote:

>Excerpts from Stephen Worthington's message of 2014-07-06 18:08:49 +1200:
>> 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.
>> 
>
>No, I don't. That's good to know, I was really hoping it wasn't the
>tuner card.
>
>> 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)?
>> 
>
>The cable runs out the back of the mythbox, through a splitter to the TV
>and then to the power injector and out through the wall. The whole thing
>is behind the TV cabinet and doesn't get poked around with much. I've
>already checked and double checked the connections. F-connectors are on
>everything except the splitter and the inputs to the TV and mythbox. Not
>sure about the cable type.
>
>> 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.
>> 
>
>I just tried to check this, but my trusty $10 multimeter only registers
>a couple of blips becuase the thing is AC. I'll take it to work later in
>the week and hook it to a proper scope.
>
>Aerial looks OK, but I think a trip to the roof may be required when I
>get the time/weather/light.
>
>> 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.
>
>For 530000, I get:
>
>Using DVB card "NXP TDA10048HN DVB-T"
>tuning DVB-T (in United Kingdom) to 530000000 Hz
>polling....
>Getting frontend event
>Overflow error, trying again (status = -1, errno = 75)FE_STATUS:
>polling....
>Getting frontend event
>FE_STATUS:
>polling....
>Getting frontend event
>FE_STATUS: FE_HAS_SIGNAL
>polling....
>Getting frontend event
>FE_STATUS:
>polling....
>Getting frontend event
>FE_STATUS: FE_HAS_SIGNAL
>polling....
>Getting frontend event
>FE_STATUS:
>polling....
>Getting frontend event
>FE_STATUS: FE_HAS_SIGNAL FE_HAS_CARRIER
>polling....
>Getting frontend event
>FE_STATUS:
>polling....
>Getting frontend event
>FE_STATUS: FE_HAS_SIGNAL
>polling....
>Getting frontend event
>FE_STATUS:
>polling....
>Getting frontend event
>FE_STATUS: FE_HAS_SIGNAL
>polling....
>Getting frontend event
>FE_STATUS:
>polling....
>Getting frontend event
>FE_STATUS: FE_HAS_SIGNAL
>polling....
>Getting frontend event
>FE_STATUS:
>polling....
>Getting frontend event
>FE_STATUS: FE_HAS_SIGNAL
>
>The program just keeps polling without exiting, so I hit Ctrl-C.
>
>I get similar output for the other muxes, although with a higher
>percentage of FE_HAS_CARRIER messages. At the current time live TV works
>on TV ONE and Prime but TV3 fails to tune.

Those messages just mean that dvbtune found nothing to tune to on that
frequency.

This is what I get when I tune to an invalid frequency:

Using DVB card "DiBcom 7000PC"
tuning DVB-T (in United Kingdom) to 520000000 Hz
dvb_frontend_parameters: frequency = 520000000, inversion = 0,
qpsk.symbol_rate = 0, qpsk.fec_inner = 3
polling....
Getting frontend event
FE_STATUS:
polling....
Getting frontend event
FE_STATUS: FE_HAS_SIGNAL
polling....
polling....
polling....
polling....
^C

And this is what it looks like when there is a transmitter on the
frequency:

Using DVB card "DiBcom 7000PC"
tuning DVB-T (in United Kingdom) to 530000000 Hz
dvb_frontend_parameters: frequency = 530000000, inversion = 0,
qpsk.symbol_rate = 0, qpsk.fec_inner = 3
polling....
Getting frontend event
FE_STATUS:
polling....
Getting frontend event
FE_STATUS: FE_HAS_SIGNAL FE_HAS_LOCK FE_HAS_CARRIER FE_HAS_VITERBI
FE_HAS_SYNC
Bit error rate: 0
Signal strength: 36040
SNR: 261
FE_STATUS: FE_HAS_SIGNAL FE_HAS_LOCK FE_HAS_CARRIER FE_HAS_VITERBI
FE_HAS_SYNC
Signal=36040, Verror=0, SNR=239dB, BlockErrors=0, (S|L|C|V|SY|)
Signal=35984, Verror=0, SNR=252dB, BlockErrors=0, (S|L|C|V|SY|)
Signal=35937, Verror=0, SNR=240dB, BlockErrors=0, (S|L|C|V|SY|)
Signal=35920, Verror=0, SNR=237dB, BlockErrors=0, (S|L|C|V|SY|)
Signal=35886, Verror=0, SNR=241dB, BlockErrors=0, (S|L|C|V|SY|)
Signal=35896, Verror=0, SNR=259dB, BlockErrors=0, (S|L|C|V|SY|)
Signal=35894, Verror=0, SNR=255dB, BlockErrors=0, (S|L|C|V|SY|)
Signal=35914, Verror=0, SNR=251dB, BlockErrors=0, (S|L|C|V|SY|)
^C


What transmitter do you receive from?  You need to look up the
frequencies for it and use them to test with.  There is a government
web page with all the transmitters on it, but I can not remember
exactly where it is at the moment.  It is referenced somewhere earlier
this year on this list, from when all the frequencies were
reorganised.  You can also use some SQL to see what is in your
database:

select distinct frequency from dtv_multiplex order by frequency;

The DVB-T frequencies are 9 digits long and in Hz - if you also have
DVB-S, they are 8 digits long (and in kHz units IIRC).

Note that the dvbtune output for signal level and s/n ratio can not be
compared between different types of cards, as the manufacturers do not
tell us what the absolute values mean.  But you can use them to
compare tuners of the same type, and to compare reception of different
transmitters using the same tuner.  My results above are using a one
of the two tuners on my Happuauge Nova TD-500 PCI card.

>> 
>> Do you have another DVB-T tuner you could plug in for comparison (eg
>> USB one on your laptop)?
>> 
>
>Unfortunately not.
>
>Thanks for your help so far!
>
>Cheers,
>
>Rob