[mythtv] diseqc

[Daniel Kristjansson]

On Fri, 2006-05-26 at 13:30 -0400, Yeasah Pell wrote:

> I'm not sure exactly what the signal monitor will be doing with the 
> approximate position information. Presumably we'll want to display that 
> on the OSD (several people seem excited about that idea), and presumably 
> it will be used as part of tuning decisions as well. As long as the 
> signal monitor doesn't do anything that actually prevents tuning of a 
> signal for the 37.5-75 seconds that the position is unknown, I'm fine 
> with leaving the persistent position feature out.
> 
> It might make sense for the signal monitor to treat a motor with unknown 
> position as if there were no motor at all, thus falling back to the same 
> behavior that exists right now during that window of startup?

Basically, the reason knowing the position would be very good for
tuning is because it would allow PAT match only tuning to be safer.
Right now we are using an SDT match for tuning with DVB, and VCT
for tuning with ATSC. Some people have complained that their DVB-S
provider only transmits an SDT every 30 seconds. They would like
to be able to tune on the PAT alone. The way I figure it SDT tuning
should be safe no matter where the dish is pointing, but we could
all PAT only tuning once we're reasonably sure the dish is pointing
in the right direction and tuned to the right transport params.
So in the normal SDT case the dish direction would only be used
for updating the UI, but with the PAT only tuning hack it would be
used to delay channel lock (but in this case the user would chose
this behaviour because presumably it is normally faster).

Knowing the Dish position might also be useful for speeding up EIT
scanning, but this is a far off dream at the moment.

-- Daniel