[mythtv-users] Mux-shifting. DVB-T retune
Klaas de Waal
klaas.de.waal at gmail.com
Sat Mar 14 16:09:26 UTC 2020
On Sat, 14 Mar 2020 at 16:20, John Pilkington <johnpilk222 at gmail.com> wrote:
> On 14/03/2020 13:14, John Pilkington wrote:
> > On 14/03/2020 12:25, Klaas de Waal wrote:
> >> On Sat, 14 Mar 2020 at 12:04, John Pilkington <johnpilk222 at gmail.com
> >> <mailto:johnpilk222 at gmail.com>> wrote:
> >> On 04/03/2020 14:48, John Pilkington wrote:
> >> >
> >> > The DVB-T/T2 scans did not find the new QAM-256 transports
> >> > automatically, and a full scan looked as if it would take a long
> >> time.
> >> > I'm afraid I let the TV tell me the new frequencies.
> >> >
> >> > "700 Mhz clearance" -> DVB-T2 now on 586, 746 and 754 MHz
> >> >
> >> I have a new problem with DVB-T2 and last night's master,
> >> 2e9f884. I'm
> >> not sure when it started.
> >> After last week's retune I had 3 DVB-T2 transports, with channels.
> >> Their frequencies are quoted above. In current scans only two are
> >> populated. 746 MHz gives no channels. VLC, also using the MyGica
> >> tuner, has the same problem with just that mux.
> >> My TV finds and plays these channels. One is BBC NEWS HD.
> >> There's a new commit, 405e049, that may affect this. I'll start a
> >> build.
> >> When VLC also has problems there might have been something changed in
> >> the multiplex.
> >> You could try with the "Complete scan data required" option unchecked
> >> (by default it is checked).
> >> A complete log of the scan, capturing the terminal output of
> >> mythtv-setup like this:
> >> mythtv-setup -v chanscan,channel,record --loglevel=debug 2>&1 | tee
> >> ms-20200314-1321.log
> >> is what I need to figure out what is happening. This will be too big
> >> for the mailing list but it can be sent to me directly.
> >> BTW the latest commit changes the numbering scheme for duplicate
> >> channels. It will not influence the scanning itself.
> >> Klaas.
> > I have the new build and will experiment soon. I forgot to say that the
> > scans reported No Lock, with all the options I tried.
> > There are political moves to stop open access in the future. May be
> > ominous.
> Hope this helps
> Indeed there is nothing received on the 746MHz. I see it donet twice, once
with what is probably the old/existing transport and once with a manually
As the 754MHz and the 586 MHz DVB-T2 transports are received correct with
the same tuning parameters the MyGica must be correct.
What I think of is that the modulation has changed and that the "auto"
setting for one or more of the parameters needs to be explicit.
Maybe you can find from the internet what the modulation parameters are. If
you find them, please send a link.
I suggest then a "Full Scan (Tuned)" on the 746Mhz and fill in the
parameters as found.
You can also just experiment a bit with the various values but you will get
a combinatorial explosion of possibilities.
I see that I still have to change the Mod Sys default to DVB-T2. This was
intended but I missed that.
Another thought about the "clearance". I was under the impression that all
broadcast frequencies are being moved to below 700Mhz to make space for
mobile/5G so it surprises me a bit that you still have to tune to 746 and
754 MHz. Are you sure your 746Mhz is not moved to a lower frequency?
BTW I am planning to reduce the range of frequencies to scan with a "Full
Scan" when I know the new limits.
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