[mythtv] diseqc
Yeasah Pell
yeasah at schwide.com
Wed May 24 20:49:20 UTC 2006
>DiSEqC 2.0 supports bidirectional commands, and the spec defines
>everything you'd need to know what the motor is doing. Unfortunately I
>don't know of any motor that supports this, and even if they existed,
>the linux dvb api doesn't support 2.0 (although many cards do.) However,
>for my setup I have the diseqc class calculate how long it will take to
>do the move based on the last known location, and the motor manufacturer
>specifications for the angular speed at 13V and 18V. It works fairly
>well, though it's obviously not as good as having real motor feedback.
>
>
This reminds me -- back when I was first doing the angular rate
calculations I encountered a problem where the EIT scanner seemed to use
a diseqc object with a different angular position than the actual last
position that the recorder used. I forgot all about this, but now that I
think about it I wonder if this is a bug that is responsible for the
occasional lost recording I get, under this kind of scenario:
[recorder runs at position 1, finishes]
[active eit scanner begins at position 1, motor moves to 1 -- doesn't
realize it was already at 1]
[active eit scanner moves to position 2, motor moves to 2]
[recorder runs at position 1, but the recorder's diseqc object still
reflects position 1, so it doesn't move]
This was on 19-fixes, I haven't tried to see if it's a problem in one of
the more recent branches, or even if it's still a problem in 19-fixes.
I'll check it out when I get a chance.
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