[mythtvnz] dvbv5-scan 22KHz tone support

[Stephen Worthington]

On Fri, 20 Dec 2024 13:22:35 +1300, you wrote:

>Anyone tried to use dvbv5-scan  to scan Optus D10 on a Sky Dish recently?
>
>I can't find any decent examples, but it looks like "-S 1" will activate
>DISEqC support for 22KHz tone.
>
>Just trying to run some test scans of Optus D10 ahead of the big switch
>over, and I'm not sure if my ​Matchmaster 10mm-dda28 is getting in
>the way.

With dvbv5-scan, I do not think it has a blind scan option - it only
works from the multiplex data in its config files.  The relevant one
in Ubuntu 24.04 is:

/usr/share/dvb/dvb-s/Optus-10-156.0E

but that does not contain any of the new Sky multiplexes.  You would
have to add them manually.

I have been able to run blind scans using DVBViewer (Windows payware)
via a SAT>IP connection to my DVB-S2 tuners running under minisatip. I
had to change the minisatip LNB settings manually to force the 22 kHz
tone on, as there are no LNB settings that actually match my fairly
standard Sky dish.  So I changed this option:

-L *:10750-10750-99999

to this:

-L *:10750-10750-00000

and restarted minisatip.  What this does is specify the LNB local
oscillator frequencies for the low and high oscillators both as 10750,
and the changeover frequency between low and high to be 0, so that the
LNB will be set to use the high local oscillator.  Switching to the
high local oscillator with the default ("Universal") type of LNB is
done by turning on the 22 kHz tone.  With my Sky dish, it does not
actually have low and high LNB local oscillators.  Instead, it seems
to have only one local oscillator, and uses the 22 kHz tone to select
the second throat that is pointed at 156.0E.  The first throat is
pointed at 160.0E.

So if you can get any scanning software to generate the 22 kHz tone
somehow (maybe via a DISEqC option), that would be better than what I
am doing by fooling around with the LNB settings.  But if not, then
you should be able to do it with the LNB settings the way I am.  If
your dish works the same way mine does.

Note to everyone - if you send 22 kHz to your Sky dish from a DVB-S/S2
tuner while your Sky box is recording, or you are recording via
MythTV, you will be switching throats and the current recordings will
fail.  Make sure to only do it when the dish is not being used, and to
switch the 22 kHz tone off when finished testing.