[linux-dvb] Re: tuning problems wih dvb-kernel

[Holger Waechtler <holger@convergence.de>]

Robert Schlabbach wrote:
> From: "Holger Waechtler" <holger@convergence.de>
>
> > Some of the VES1820 based cards have the I/Q wires between
> > PLL/Synthesizer and Demodulator swapped, so you don't know in advance
> > whether INVERSION_OFF is really INVERSION_OFF or not.
>
> Then the driver should detect the hardware type and makre sure that
> INVERSION_OFF really results in the entire card being "inversion neutral".
> We've actually had this discussion before... :)
:) yes -- if you find a way to do this reliably, patches are welcome!


> I don't think a "try&error" method at runtime is the proper solution to
> this.
well, it worked pretty good in most cases...


> > If I remember correctly the Hauppauge cards designed by Technotrend
> > and the old Siemens cards have the exactly opposite setting.
>
> I have both a Siemens-Cable card as well as a TechnoTrend budget DVB-C card
> (0x1004, with ALPS TDBE2 tuner) and they both work the same - the INVQ bit
> has to be SET for the card to be inversion neutral (the tuner spectrally
> inverts the signal by using a PLL frequency ~36MHz above the target RF).
>
> i.e. for those two cards:
>
> INVERSION_OFF -> SET INVQ bit in CONF
> INVERSION_ON  -> CLEAR INVQ bit in CONF
hmmm, don't remember off-hand which card revisions caused the troubles 
exactly...

Holger



--
Info:
To unsubscribe send a mail to ecartis@linuxtv.org with "unsubscribe linux-dvb" as subject.