[mythtv-users] Mux-shifting. DVB-T retune

[Stuart Auchterlonie]

On 14/03/2020 16:09, Klaas de Waal wrote:
> 
> 
> On Sat, 14 Mar 2020 at 16:20, John Pilkington <johnpilk222 at gmail.com
> <mailto: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>
>     >> <mailto: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 230
>     >>     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
> 
>     https://drive.google.com/open?id=1SW5c-KbgpghSSvqhs5walkD6-MLJ13Zs
> 
> 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 added transport.
> 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.
> 
> 

The clearance still isn't complete. The current mplexes which are
up in the 700Mhz range are scheduled to be vacated over the next few
years, yet i cannot for the life of me find an actual *schedule* for
this, apart from the original one due for completion in the next few
months. This schedule still leaves various 700Mhz mplexes in
operation.

I'm currently missing 2 multiplexes of DVB-T2 channels because the
700Mhz range is outside the original aerial group for the transmitter
(Crystal palace if you care)

In order to get them back, i'd either have to get a new aerial for
a few years, or a new aerial pointing at an alternative TX.


Regards
Stuart