[linux-dvb] [patch/resend] dvb pll library

Holger Waechtler holger at qanu.de
Fri Feb 18 13:00:41 CET 2005


Gerd Knorr wrote:

>Holger Waechtler <holger at qanu.de> writes:
>
>  
>
>>On most modern cards (ancient ones like the ves1820 based, more modern
>>ones like the TDA10045-based ones, and really new ones like the
>>MT352-based Pinnacle 300i) the PLL settings depend on the external
>>circuitry and cannot really get shared between different hardware
>>designs.
>>    
>>
>
>The only thing handled by the pll lib is the calculation of the 4
>control bytes, _not_ the actual hardware access, exactly because of
>the different hardware designs.
>  
>

charge pump current, time slope and filter constants are all encoded in 
the control bytes, and usually very dependent on the actually used board 
design and external components. Even if some drivers share the same 
settings this is more a lazy compromise (and especially in the case of 
the VES1820 one that hurts many users again and again and seriously 
degrades receiption performance, especially at high modulation ratios. 
Same for the different Hauppauge and Twinhan designs with discrete 
combination of analog tuner and digital demod circuitry).

we explained this several times before.

Holger





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