[linux-dvb] Some tests on Avermedia A700

Matthias Schwarzott zzam at gentoo.org
Sat Feb 9 22:14:06 CET 2008


On Samstag, 9. Februar 2008, Eduard Huguet wrote:
> Hi, Matthias
Hi Eduard!

>     I've been performing some tests using your patch for this card.
> Right now neither dvbscan nor kaffeine are able to find any channel on
> Astra (the sat. my dish points to).
>
> However, Kaffeine has been giving me some interesting results: with your
> driver "as is" it's getting me a 13-14% signal level and ~52% SNR when
> scanning. Then, thinking that the problem is related to the low signal I
> have I've changed the gain levels used to program the tuner: you were
> using default values of 0 for all (in zl1003x_set_gain_params()
> function, variables "rfg", "ba" and "bg"), and I've changed them top the
> maximum (according to the documentation: rfg=1, ba=bg=3). With that, I'm
> getting a 18% signal level, which is higher but still too low apparently
> to get a lock.
>
> I've stopped here, because I really don't have the necessary background
> to keep tweaking the driver. I just wanted to share it with you, as
> maybe you have some idea on how to continue or what else could be done.
>

So I can do only this guess:
I changed demod driver to invert the Polarization voltage for a700 card.
This is controlled by member-variable voltage_inverted.

static struct mt312_config avertv_a700_mt312 = {
        .demod_address = 0x0e,
        .voltage_inverted = 1,
};

Can you try to comment the voltage_inverted line here (saa7134-dvb.c: line 
865).

BUT: If this helps we need to find out how to detect which card needs this 
enabled/disabled.

Regards
Matthias

-- 
Matthias Schwarzott (zzam)



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