[linux-dvb] Re: My DVB-c patch (Re: The drivers and HTV)

[Ralph Metzler <rjkm@metzlerbros.de>]

Holger Waechtler writes:
 > >  > that both frontends loose lock due to RF interferences.
 > > 
 > > 
 > > Does this really happen with multiple cards or only if two tuners are
 > > on the same card/board right next to each other?
 > 
 > The strongest effect you can see when 2 poorly shielded frontends are 
 > connected directly side by side. But if the GND routing is not optimal 
 > this happens even when the frontends are placed wider away.
 > 
 > The good thing about PCI cards is that they usually have a solid GND 
 > plane in the PCB between the 2 tuners, but for STBs this is rarely the 
 > case...

That's what I meant. Is it necessary to use bending when using several
PCI cards or only in multi-tuner STBs?
When using PCI cards with 2 tuners one probably also needs it.

 
 > >  > >>- Has anyone ever tested this auto inversion thing?  DVB-c is far too slow
 > >  > >>  to tune and lock for this auto inversion code to work.  Therefore you
 > >  > >>  need to manually set it.
 > >  > > 
 > >  > > 
 > >  > > I had inversion turned off with the reg0 |= 0x20 code in ves1820.c
 > >  > > (Your HTV channels.conf specifies inversion off for all channels, hope that 
 > >  > > was right :)
 > >  > 
 > >  > You should use INVERSION_AUTO if you don't know for sure your providers 
 > >  > inversion settings.
 > > 
 > > 
 > > But it should also be possible to set it manually.
 > 
 > This is only possible if you know how Tuner and frontend are connected. 
 > For the ves1820 are both versions out there, as well for the stv0299 
 > based frontends. Some verndors simple swapped I and Q pins, so the 
 > spectrum is virtually mirrored.

For the stv0299 I let the driver configure this according to card type.
Works nicely for Nova, KNC, Flyvideo, etc. who all seem to be
determined to use a different combination of settings/ports for
inversion, voltage and power ...

I'll add it for ves1820 as soon as I know which inversion I really
have. To make it more confusing, ISH (the cable provider here in
Nordrhein-Westfalen, who used to be KabelNRW, who were part of
Callahan, who bought it from Deutsche Telekom ...) just changed the
inversion last year when they modified their cable for internet (2Mbit, very
nice :-) and I still don't know which one I really have.

Which inversion do you have and which setting of the ves1820 on a 
Siemens card corresponds to it? 


Ralph





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