[linux-dvb] Re: Cinergy 1200 DVB-T TDA10046H / auto mode causes problems

[Andrew de Quincey <adq_dvb@lidskialf.net>]

On Thursday 18 Nov 2004 20:31, Christian Cier-Zniewski wrote:
> Hello,
>
> I am using the latest CVS HEAD source with Kernel 2.6.8.
> The tda1004x driver seems to have problems with quickly tuning to
> another frequency. Sometimes it did not tune at all. I tried this with
> vdr-1.3.16. Switching channels was very slow.
>
> After studying the code a little bit, I found the following comment:
>
> // Hardcoded to use auto as much as possible
> // The TDA10045 is very unreliable if AUTO mode is _not_ used. I
> // have not
> // yet tested the TDA10046 to see if this issue has been fixed
> //fe_params->u.ofdm.code_rate_HP = FEC_AUTO;
> //fe_params->u.ofdm.guard_interval = GUARD_INTERVAL_AUTO;
> //fe_params->u.ofdm.transmission_mode = TRANSMISSION_MODE_AUTO;
>
> After commenting out the above three lines, everything worked pretty
> fine and quick. My frontend uses a TDA10046H.

Hi, I tried the sample of that card I have out. However, the one I have gives 
terrible reception - errors constantly. I know it isn't the signal because 
all other types of DVB-T card in the same machine give a perfect signal. I 
assume the signal you're getting is OK, otherwise you would have mentioned 
it.

There are two possible causes as far as I can see:

1) I've heard these cards are supposed to be quite picky about PCI buses. 
Certainly dvbtune reports a BER of 0 from the demod, but the actual data 
received by my test program is full of errors.

2) Could there be some difference in the type of signal? The one I am trying 
is:

frequency: 634166670
bandwidth: 8Mhz
hp-rate: FEC_3_4
lp-rate: FEC_3_4
modulation: qam-16
transmission-mode: 2K
guard-interval: 1/32
hierarchy: none

The only other time I tried this demod (tda10046) was on a TT USB Nova-T. 
However, it worked fine there.