[linux-dvb] Re: TechnoTrend PCI DVB-C 2.1 success

[Lauri Pesonen <lauri.pesonen@firsthop.com>]

Hello list,

I got my system working! Both cards (nova, full-featured). And VDR as 
well. The downside is, I don't know what I did differently from sunday :( 
I'm using a snapshot driver from last week and VDR 0.99pre1. VDR has been 
patched to use QAM_128 instead of QAM_64. The driver has been patched to 
support the TT card tuner chip. I also increased the waiting time that 
Ralph mentions below from HZ/2 to HZ*2. I did not disable zigzagging like 
Kenneth did (actually I had zigzagging disabled earlier, maybe that's 
it...). I have not tried any other values besides HZ*2. I think I'll try 
that today in order to find an optimal number.

A short recap: In the beginning the firmware did not load. I swapped card
slots. recompiled the driver a couple of times and played with the debug
options after which the firmware was loaded successfully IIRC. I think it 
was related to the slots/IRQs. Then came the tuner patch from Joachim, but 
my cards would not tune. After that Kenneth posted his results from 
disabling the zigzagging. Now it looked like my card would in deed tune to 
a frequncy: FE_READ_STATUS returned all the right bits, FE_HAS_LOCK etc. 
The only problem was that there was no image on composite out. That was 
fixed yesterday. I tried different driver versions (the two drivers from 
Klaus' page and the snapshot that I had from last week). I had compilation 
problems with the September snapshot from Klaus' page (EXPORT_PARM()) 
which are probably related to my kernel update (2.4.16). I switched back 
to the Januare snapshot I had and suddenly things started working!

Some problems though: while using VDR, the cards stopped tuning at some 
point. VDR switched the channel and showed the OSD entry about the current 
programme, but the was no picture. I restarted VDR and things worked 
again. I also managed to crash VDR at least oncu by using REMOTE=KBD and 
DEBUG_OSD=1 and then hitting the MENU key repeatedly (I got frustrated 
since the thing did not respond ;).

Another problem is that the cards do not seem to tune to frequencies like 
146, 154, 162, 170MHz. These are valid frequencies for my cable provider 
(I got the numbers from the cable provider), but the card does not tune to 
those freqs. It did not work under Windows either. So I'm wondering 
whether its a bug in the card; it cannot tune so low. Or if my cable 
provider has a lousy signal level.

Any how, thanks for all your help!

BR, Lauri

On Mon, Jan 14, 2002 at 12:59:04AM +0100, Ralph Metzler wrote:
> Falck Kenneth writes:
>  > Hi,
>  > 
>  > My card just tuned in here in Helsinki!!!
>  > 
>  > I made a modification to dvb_frontend.c's fe_zigzag() to always keep the
>  > initial frequency. Apparently this gives the card enough time to get a lock
>  > on the signal; otherwise the frequency zigzagging loses it.
>  > 
>  > I suppose the signal quality is so bad here, that tuning often takes very
>  > long. Or maybe some parameter is not exactly right but still makes tuning
>  > possible if one waits long enough?
> 
> 
> The default waiting time between zigtag steps already is much longer
> for DVB-C than for DVB-S (1/2 s instead of 1/10 s).
> With 1/10 s for DVB-C I also had problems.
> 
> Have you tried increasing this value for DVB-C?
> If yes, how high do you have to set it?
> 
> 
> Can you see what kind of crystal they are using for the Rev. 2.1 card?
> The Siemens card uses 57.84 MHz. I heard the DBOX2 cable version uses 
> a VES1820 with 69.6 Mhz crystal. Maybe TT also uses a slightly
> different crystal on their card?
> 
> 
> Ralph


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