[linux-dvb] Re: DVB-C driver (Re: More thoughts on coldbootdriver crash)

[Ragnar Sundblad <ragge@nada.kth.se>]

--On den 4 januari 2003 03:41 +0200 Jaakko Hyvätti <jaakko@hyvatti.iki.fi> 
wrote:

>   Anyway, the most important thing is that zigzag is disabled.

I had problems with the zigzaging too when trying to troubleshoot
my card. It also seemed to not want to stop when retuning, it
seemed to continue zigzaging on the new channel, but I am not
sure about that. Zigzaging might be good in some cases, but not
when playing with the tuner. :-)

> The tuning
> takes 1-2 seconds in worst case.  I guess it is the slow afc, maybe it
> takes time to settle.  Are there any parameters to make that a bit faster?
> Charge pump currents or such?

1-2 seconds is pretty good, don't forget that both the frontend
and the mpeg decoder needs to get in sync. I could improve
settling time and time-to-picture to under 1 sec by uping the
charge pump current and increasing the stepsize, but it can also
get instable. I am not sure it would be a good idea to optimize
it for your card and just hope it works for all cards on all
bands and put it in the CVS driver. I'd prefer having the driver
in the CVS do as the manufacturer says, or maybe being trimmed by
an expert (which I am not).

But hey, give it a try and see what you find! Try different
combinations of stepsize and pump current on different bands,
and you could also try coarse tuning it with some settings
and fine tune it/decrease noise with some other some time
later.

/ragge




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