[mythtv-users] Indoor HD antenna question

Fri Apr 13 19:15:36 UTC 2018

On Fri, 13 Apr 2018 17:17:34 +0000, you wrote:

>Seems that the driver doesn't seem to load - or that's what I am getting
>when I look in the dmesg.

There is some confusion going on here.  MythTV is saying that
/dev/dvb/adapter0 is an "Air2PC v2" tuner, which is a USB ATSC tuner.
But the full dmesg does not show any sign of such a tuner.  Instead,
it shows messages that would be expected for a Avermedia AverTVHD
card.  But that card is not documented as being an ATSC tuner.  So I
have to guess that the Avermedia AverTVHD card that you have is
actually a variant of the card manufactured for the US market that
does ATSC instead of DVB-T.  Somehow MythTV seems to be giving the
card the "Air2PC v2" name instead of the correct name.  I do not know
where MythTV gets those names, so that is possible, but I would have
expected that it got the name from the hardware or drivers somehow, so
it is a worry that it has the wrong name.

The error messages about saa7134_alsa are impossible to pin down as to
which card they apply to.  But the name saa7134 is a chip that is
likely used on the AverTVHD card.  The _alsa at the end suggests that
the driver having problems loading is for the audio side of the card,
rather than video, but any driver not loading is going to cause
problems.  It might be an idea to try removing the PVR-150 card and
booting without it to see if those saa7134_alsa error messages go
away.  That would indicate that the bad driver was being used for the
PVR-150, rather than the AverTVHD card.

The only way I know of to fix that driver problem is to get a working
driver from somewhere.  That can involve finding the source code and
compiling it.  The kernel comes with a set of V4L (Video for Linux)
drivers that are conservatively chosen - they are older and well
tested.  But it looks like the testing has missed your card somehow
and its driver is not compatible - maybe the testers no longer have
one of your model of tuner card to test with.  If you are lucky, the
problem you are having has already been fixed in a later version of
the V4L drivers and if you install the latest version of them, it will
work.  This page has how to do that:

https://www.linuxtv.org/wiki/index.php/How_to_Obtain,_Build_and_Install_V4L-DVB_Device_Drivers

If, after trying the latest V4L drivers, you want to revert back to
the V4L drivers that are built into kernel packages, you have to
reinstall all the kernel packages.  The method of doing that depends
on what distro you are using.

One other option is to go back to an older kernel that is compatible
with the drivers you have.

It is possible to scan for channels from the command line.  You do
that by using the "scan" command.  Use "man scan" to tell you the
options.  In Ubuntu, there is a file here:

/usr/share/dvb/dvb-legacy/atsc/us-ATSC-center-frequencies-8VSB

that provides the "initial-tuning-data-file" for scan's -c option.  It
contains all the ATSC frequencies, so many may not be used in your
area and will fail to tune.  Let scan go through the whole list of
frequencies, which will take a while.  If it will scan, but does not
see any channels on any frequency, then there is likely a problem with
the signal from the aerial.  If it will not scan, then the driver
problem is likely making the tuner non-functional.

I think you said that you connected the aerial directly to a TV and
the TV could see your channels.  Is that correct?  If so, make sure
your TV is able to see the channels before you move the connections
(without bumping the aerial) to the MythTV box and run "scan".  That
way you can be sure there is a valid signal for the tuner to use.

In case your distro does not have the us-ATSC-center-frequencies-8VSB
file or some equivalent, here is what is in it:

root at mypvr:~# cat
/usr/share/dvb/dvb-legacy/atsc/us-ATSC-center-frequencies-8VSB
A 57028615 8VSB
A 63028615 8VSB
A 69028615 8VSB
A 79028615 8VSB
A 85028615 8VSB
A 177028615 8VSB
A 183028615 8VSB
A 189028615 8VSB
A 195028615 8VSB
A 201028615 8VSB
A 207028615 8VSB
A 213028615 8VSB
A 473028615 8VSB
A 479028615 8VSB
A 485028615 8VSB
A 491028615 8VSB
A 497028615 8VSB
A 503028615 8VSB
A 509028615 8VSB
A 515028615 8VSB
A 521028615 8VSB
A 527028615 8VSB
A 533028615 8VSB
A 539028615 8VSB
A 545028615 8VSB
A 551028615 8VSB
A 557028615 8VSB
A 563028615 8VSB
A 569028615 8VSB
A 575028615 8VSB
A 581028615 8VSB
A 587028615 8VSB
A 593028615 8VSB
A 599028615 8VSB
A 605028615 8VSB
A 611028615 8VSB
A 617028615 8VSB
A 623028615 8VSB
A 629028615 8VSB
A 635028615 8VSB
A 641028615 8VSB
A 647028615 8VSB
A 653028615 8VSB
A 659028615 8VSB
A 665028615 8VSB
A 671028615 8VSB
A 677028615 8VSB
A 683028615 8VSB
A 689028615 8VSB
A 695028615 8VSB
A 701028615 8VSB
A 707028615 8VSB
A 713028615 8VSB
A 719028615 8VSB
A 725028615 8VSB
A 731028615 8VSB
A 737028615 8VSB
A 743028615 8VSB
A 749028615 8VSB
A 755028615 8VSB
A 761028615 8VSB
A 767028615 8VSB
A 773028615 8VSB
A 779028615 8VSB
A 785028615 8VSB
A 791028615 8VSB
A 797028615 8VSB
A 803028615 8VSB