[mythtv] Current SVN DVB-S zapping problems (diseqc?)

Simeon Simeonov simeonov_2000 at yahoo.com
Tue Aug 29 00:59:02 UTC 2006

I also have very similar problem to what Lukas
described and have been trying to do some testing.
My setup is Twinhan 102g->Rotor 1.2->switch. Switch
port 1 is connected to one LNB and switch port 2 is
connected to universal LNB. I am running the latest
SVN and a week old v4l-hg drivers on fedora core 5
The switching worked 100% with the patch following:
and retune procedure. So the hardware should be OK.
Since version 10585 I am not able to switch to
position 2 most of the time. Inserting larger delays
after diseqc commands helped somewhat and ocasionally
the switching occurs. What is interesting is that once
on position 2 I have hard time switching back to 1.
Even restarting the backend does not help. Very often
the only way is to turn off the computer and back on.

I also confirmed using a voltmeter that the switching
does not occur - so it must be the diseqc. The voltage
is set correctly 100% of the times.

Trying to isolate the problem I bypassed the rotor and
tried to get reliable switching to my universal LNB on
port 2 from port 1. Here I observed something similar
to what Lukas described. When I switch from port 1 to
port 2 the first tune is sucessful. Switching to a
second channel on the same input source would very
often fail even if the channel is one the same
multiplex ???? Looking into the code I see that the
only thing that happens when we switch to channel on
the same input is the tone switching for the universal
LNB. I hacked the code to avoid unnecessary tone
switching (i.e if the tone is off I do not issue
SET_TONE_OFF) and for my surprise channel szapping
became much more stable. Unfortunately it is still not
100%. Adding the rotor and testing with it made the
situation much worse.
So I am still not sure what is the reason for all that
but it seems to is more like ioctl are failing for
some reason.

I thought I would share this with you and see if
someone has any ideas.


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