[mythtv-users] USA OTA FCC frequency rescan?

Joey Morris rjmorris.list at zoho.com
Mon Aug 12 22:51:51 UTC 2019

James Abernathy <jfabernathy at gmail.com> wrote on Mon, Aug 12, 2019 at 09:13:42AM -0400:
> Has anyone worked out a way to do the rescan without messing things up??

I just ran through a test of this over the weekend, and it sounds like the
others who responded have covered pretty much everything I encountered. A few
notes from my test are below. A lot of this is just general channel scanning,
not specific to the repack, but it had been a long time since I did this, so it
was good to get a refresher before the big day arrives.

I didn't have any trouble running the channel scan within MythTV (from the
Channel Editor page in mythtv-setup). I deleted all my channels first and then
inserted everything that was found in the scan. Without deleting everything
first, I always get confused by the prompts about manually entering channels, so
it's easier for me to start from scratch.

Before this weekend, my last scan was in 2014, so I was concerned about changes
to the call signs breaking my "only on this channel" recording rules. I had 2
channels where this was an issue: "WRAL_HD" changed to "WRAL HD", and "WRAZ-HD"
changed to "WRAZ HD". (There may have been others with new call signs, but these
were the only 2 that also had recording rules attached to them.) I found the
problematic channels by querying the database after my rescan with the following

  select r.station, ch.callsign
  from (select distinct station from record) as r
    left join channel as ch
      on r.station=ch.callsign;

and looking for anything where the callsign was NULL. I then edited the `record`
table in the database to update the old call signs to the new ones. Later I
verified in my Upcoming Recordings screen that the rules I changed were picking
up shows on these channels as expected.

I re-ran tv_grab_zz_sdjson to re-configure my XMLTV ids, only because I hadn't
run it in a while, and I knew a few new subchannels had been picked up in the
scan that weren't there the last time I ran tv_grab_zz_sdjson. I'm hoping this
won't be necessary after the repack is complete, but we'll see.

I half-expected the channels to already be airing on their new frequencies,
because we're in the testing period, but they weren't. A period of overlap where
channels are airing on both the old and new frequencies simultaneously would be
helpful for testing, but I'm not counting on it.

Because the channels are moving to lower frequencies, some from UHF to VHF, you
may need to review your antenna situation. It's possible that your antenna may
not pick up the new frequencies as well as the old ones.

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