[linux-dvb] TT S2-3200 driver

Manu Abraham abraham.manu at gmail.com
Sun Sep 7 22:53:59 CEST 2008

Ales Jurik wrote:
> Hi,
> please try attached patch. With this patch I'm able to get lock on channels 
> before it was impossible. But not at all problematic channels and the 
> reception is not without errors. Also it seems to me that channel switching is 
> quicklier.
> Within investigating I've found some problems, I've tried to compare data with 
> data sent by BDA drivers under Windows (by monitoring i2c bus between stb0899 
> and stb6100):
> - under Windows stb6100 reports not so wide bandwith. (23-31MHz, 21-22MHz and 
> so on).
> - under Windows the gain is set by 1 or 2 higher.

When you set for a higher gain, (generally: for a Class C/tuned
amplifier) the available bandwidth becomes narrower. So what you see, is
quite typical for a pre-stage set up for a higher i/p gain factor.

> When setting those parameters constantly to values used under Windows nothing 
> change. So maybe some cooperation with stb0899 part of driver is necessary. 

When the bandwidth changes, the stb0899's step size also might change,
though the demodulator can easily track a slightly off-centered signal,
though not the ideal case. Involves a bit of an additional overhead on
the on-chip CPU, as far as i can think.

> Also it is interesting that clock speed of i2c bus is 278kHz, not 400kHz 
> (measured with digital oscilloscope). But this should not have any influence.
> Maybe somebody will be so capable to continue?

The patch looks fine as to temporarily disable the PLL loop initially
and enable it later on. Will apply this change.


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