[mythtv] Problems tuning ATSC w/ HDHR and 0.21? LaGv Partial Lock?

[Mark Paulus]

Derek Atkins wrote:
> Hi,
> 
> My cable provider decided that they no longer want to clear-QAM my
> local HD stations so I decided to re-task one of my HDHR boxes with
> an OTA antenna.  It mostly works (although I must admit that the
> signal isn't as strong as the cable company's)...
> 
> The scanning process seemed to work okay, but when I walk through
> the stations it cannot tune one of them.  When I try the OSD says:
> 
>   (Signal 100 % LaGv) Partial Lock
> 
> Looking at my backend log I see the following:
> 
> 2008-05-29 22:52:31.136 Could not find channel 56_1 in TVCT
> 2008-05-29 22:52:31.137 
> VCT Terra: channels(3) tsid(0x553) seclength(143)
> Channel #0 name(WHDH-HD) 7-1 mod(ATSC 8-VSB) cTSID(0x553)
>  pnum(3) ETM_loc(0) access_ctrl(0) hidden(0) hide_guide(1) service_type(2) source_id(1)
>  descriptors length(17) count(1)
>   Service Location Descriptor (0xa1) length(15)
> 
> Channel #1 name(WHDH-SD) 7-2 mod(ATSC 8-VSB) cTSID(0x553)
>  pnum(4) ETM_loc(0) access_ctrl(0) hidden(0) hide_guide(1) service_type(2) source_id(2)
>  descriptors length(17) count(1)
>   Service Location Descriptor (0xa1) length(15)
> 
> Channel #2 name(WHDH TV) 7-0 mod(Analog) cTSID(0x552)
>  pnum(65535) ETM_loc(0) access_ctrl(0) hidden(0) hide_guide(1) service_type(1) source_id(3)
> 
> Strangely WHDH is a different station (and it comes in just fine).
> 
> I saw a posting from a couple years ago that mentioned setting atscsrcid
> but in my case atscsrcid (in the channel table) is NULL, so I'm
> guessing that doesn't apply anymore.
> 
> I did capture the output of "mythtv-setup -v channel,siparser" when
> scanning these stations, but mythtv-setup CRASHES at the end of the
> scan process when run in this level of verbosity.  No, I haven't
> grabbed a backtrace of the segv.  I suppose I can do that tomorrow,
> but I really want to get this station tuning in right but I'm not
> sure what tweaks to the database I might need to do.
> 
> All help would be greatly appreciate.
> 
> Again, this is 0.21 (current fixes branch as of a couple days ago).
> 
> Thanks in advance!
> 
> -derek

Check the wiki for "Adding_QAM_Channels_For_HDTV_Tuner_Cards":
http://www.mythtv.org/wiki/index.php/Adding_QAM_Channels_For_HDTV_Tuner_Cards.

In this case, the section you want would be the part about 
"Scanning for Channels".  This will show you some tools that
you can use outside of mythtv to investigate your channel selection.

You might also need to adjust the orientation of your antenna slightly,
or get additional antennas to get a quicker/better lock.
You can also check out what stations you should be able to get,
and where they are on the antennaweb site:
http://antennaweb.org.  Hit the "Choose an antenna" button, put
in your address, and see what's available for you.
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