[linux-dvb] Re: Siemens DVB-C and QAM_128

[Panu Kekäläinen <pkekalai@cc.hut.fi>]

On Fri, May 03, 2002 at 09:58:50AM +0300, Lauri Pesonen wrote:
> On Thu, 2002-05-02 at 18:03, Panu Kekäläinen wrote:
> > On Sun, Apr 28, 2002 at 07:24:56PM +0300, Panu Kekäläinen wrote:
> > > I have installed a Fujitsu-Siemens DVB-C card. The problem is that it can not
> > > tune to multiplexes which use 128QAM modulation.
> > > 
> > 
> > I have started to debug this problem. Is there any documentation for VES1820
> > available? Currently I'm interested about the registers that are set when
> > modulation type is selected, but of course I would like to see the full
> > documentation.
> > 
> 
> FYI: I have a TechnoTrend DVB-C full featured card which tunes both to
> QAM_&¤ and QAM_128 bouquets. I'm using VDR with my DVB-C card and I
> hacked VDR to parse the used QAM value from the channel definition in
> channels.conf. 

Yes, that was the first thing I did also. But since it did not work I started
to dig a little deeper. For example, I'm using dtv_scan, different version for
both modulations. The only QAM_64 bouguet available tunes and locks always at
first try.

If QAM_64 scanner finds signal and carrier occasionally in QAM_128 frequencies,
but of course can not lock.

But if I try to scan QAM_128 modulated channels. Frontend finds occasionally
signal and carrier around the QAM_64 frequency. But it cannot lock to
QAM_128-bouquets either. Tuner starts zigzagging around the set frequency. (I
also tried to disable the fe_zigzag and increase the waiting time - with no
success)

> Are you sure that the driver is the problem and not the software
> interfacing to the driver?

No, not sure at all. :) But it was my best guess after hours of hacking with
sources. Could you please send me the patch you have made to vdr sources, I
could try those also. If that does not work, I guess I must install windows and
test the card in that environment, not that I'd like to. 

It would also be nice to hear if someone with Siemens card has succesfully
tuned to QAM_128 multiplex. (Which seems to be used only in Finland...)
Funny, I bough Siemens instead of Technotrend card because I had read that
TT-cards had problems with HTV-cable...

	-Panu





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