[linux-dvb] stv0297: improvement for qam256 modulated channels

Johann Friedrichs johann.friedrichs at web.de
Sun Oct 28 13:11:52 CET 2007


Hi Oliver, Hartmut

I have to modify my last statement concerning this patch. I forgot that
I had to use a frequency shift in av7110.c to achieve a good reception.
If I set this shift to 0 and use the new value of initial_demod_freq I
get a lock again on QAM256-channels with reception as good as before.
As this freq shift also improved reception on QAM64-channels I'm at the
moment using 6718 for QAM256 and QAM64 with resulting BERs in the same
range as with unpatched stv0297.ko and a frequency shift of -250000.
Maybe this also sheds some light on the discussion about shifting
frequencies on vdr-portal.de

Oliver Endriss schrieb:
> Hi,
> 
>> Oliver Endriss <o.endriss at gmx.de> wrote:
>>> e9hack wrote:
>>>> I did eavesdrop the i2c-bus on the TT-C2300 on windows. The
>>>> initialization of the stv0297 is a little bit different. If I
>>>> change the value for the initial demodulation frequency, the ber
>>>> value is reduced to a fourths.
>>> @all:
>>> please test with QAM256 channels and report any problems.
>>>
>>> If nobody objects I'll commit this patch.
> 
> Apparently we cannot use 6718 for all cards.
> So the patch must be modified...
> 
> @TT/Hauppauge DVB-C 2300 users:
> Are there any problems with this patch?
> 
> CU
> Oliver
> 




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