[linux-dvb] Re: VES1820.c question

[Holger Waechtler <holger@convergence.de>]

Hi,

Dennis Noordsij wrote:
>>>Now, I understand there can be a million reasons why the sourcecode does
>>>something else, and I wouldn't know any of them, but the reason I am
>>>asking is that in order to tune to QAM_128 (remember Siemens DVB-C) Marko
>>>discovered register 1 should be set to 120 instead of 126 for QAM_128.
>>
>>(Hmm, I'd suppose a typo which did not showed up in our tests:)
>>
>>Unfortunally we have only QAM_64 transmissions here, and there the value
>>was correct...
>>
>>
>>>Which brings the
>>>question, why does a different value than the datasheet work for for
>>>example QAM_64, but not for QAM_128 ?
>>
>>For QAM_64 values in registers 1 and 9 were equal (106).
> 
> 
> DUH! 
> True :-)) Didn't notice :)
> 
> The one thing I'm still wondering about is that the Hauppauge DVB-C also uses 
> a VES1820 (according to the driver output - "ves1820 as used on the Siemens 
> DVB-C"), and it tunes QAM_128 fine with the unmodified register 1 values.
> 
> Also, is there any difference at all between the Vista and the Philips 
> VES1820's ? Or just the markings?

I suppose this problem is caused by the different tuner module or PLL. 
If somebody finds a parameter set that works better please contact me.

- Holger




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