[mythtv] Current DVB problems rundown

Daniel Kristjansson danielk at cuymedia.net
Sat Sep 10 02:32:19 UTC 2005

On Sat, 2005-09-10 at 03:53 +0200, Kenneth Aafløy wrote:
> Lørdag 10 september 2005 03:40, skrev John P Poet:
> > Playing with azap, I have seen it take up to 20 seconds to get a lock
> > on that station (KOB-DT 4-1 or 26-3).
> >
> > Once it gets a lock, it holds it.  Once it gets a lock, I can stop
> > azap and restart it, and it immediately gets a lock.
> It could be something related to zig-zag scanning, if atsc frontends
> permit that, since if you already have a lock it won't do it.
> It could also be related to an internal scanning routine (they do exist)
> which is not set up properly.
This would be my guess, the frequency is far enough off that the
driver/hardware has to hunt for it.

I would try adjusting the frequency in 100Mhz increments in each
direction until azap can no longer find the channel at all. Make
sure you tune to a completely different channel between each try.
Then pick a frequency in the center of the range that works at all.

I've talked to John Pullan about adding something like this to
the setup program as an "optimize frequency of each transport" 
process. Though we would probably use a binary search in the 
range on each side of the center frequency and then scan that
range at regular intervals, with time to tune as used to shape
the response curve estimate. With a lookup table to avoid 
redundant tunes of course.

-- Daniel

More information about the mythtv-dev mailing list