[linux-dvb] Re: VES1820 and BSRV2 issues

[Holger Waechtler <holger@convergence.de>]

Dennis Noordsij wrote:
> On Wednesday 16 October 2002 19:14, you wrote:
> 
>>Hi everybody,
>>
>>I appied some changes which make the open issues about old BSRV2
>>revisions and the strange modulation dependent offsets in DVB-C more
>>robust, the zigzag scan catches now catches after some trials the right
>>frequencies.
>>
>>For those of you who want to go on debugging the VES1820 code (and that
>>would be pretty good since it could speed up tuning noticable) you might
>>want to enable the printk() in dvb_frontend.c, line 332,
>>dvb_frontend_set_parameters() to show the actual frequency offset.
>>
>>a side note: maybe it's better not to play with the reference AGC value
>>but the AGC timing constants...
>>
>>- Holger
> 
> 
> Tried again the latest CVS head last night, it will tune to QAM64 after a few 
> tries (not stably though), but not to QAM128, although I think it is a 
> different kind of problem than the ves1820 register values.

I introduced a bug, sorry! Could you please try again?


> REL-0-9-2 tunes very fast and never fails, but with 2 cards in one PC I get 
> occasional artifacts and glitches (never does that with 1 card), and only on 
> one of the 2 cards. I even got a cable signal amplifier because I figured 2 
> splitters could cause problems. It helped a lot (without amplifier the 
> glitches were much worse) but it's not perfect yet.

in NEWSTRUCT/HEAD is some code to prevent interference between tuners, 
could you please try this?


> Doesn't QAM128 allow denser packing of DVB data in a frequency, making it also 
> more sensitive? (i.e. needs a better signal)

yes, QAM128 is more sensitive to noise.


> Somehow I feel the new firmware with the HEAD drivers would be more solid, if 
> only I could get them to tune :-) 

the firmware is the same, we just work around some bugs and catch some 
constellations that might crash the ARM.

Holger



-- 
Info:
To unsubscribe send a mail to listar@linuxtv.org with "unsubscribe linux-dvb" as subject.