[linux-dvb] Re: New UK DVB-T channels testing

[Lauri Pesonen <lauri.pesonen@iki.fi>]

On Wed, Oct 09, 2002 at 11:51:18AM +0200, Holger Waechtler wrote:
> Klaus Schmidinger wrote:
>
> >  The NIT reports frequencies like 283000000Hz when I'm using 282750000Hz
> >  with VDR. So The NIT reports the 'official' freqs without the offset.
> >  Offsets are -250kHz for QAM_128 freqs and -125kHz for QAM_64 freqs.
> >
> >Therefore it should be sufficient to store the "center frequency" and 
> >allow for
> >an offset handling, which in case of DVB-T could be done by an 'O' 
> >parameter
> >(note that it's the character between 'N' and 'P', not the number 'zero'), 
> >and in case of DVB-C a table of offsets for the various QAM modes should 
> >do the trick.
> 
> Are you sure that these offsets are related to the used modulation? What 
> makes you sure of that?
> 
> Holger

I emailed about theo ffset in DVB-C in Finland (the text segment Klaus 
quoted above). 

Some guy in Finland (sorry, I can't remember your name) came up with the 
offsets after trial and error. There is no guarantee that they are correct 
or that the offset is related to the modulation. Actually the only QAM_64 
bouquet in my providers network is on 162MHz and all QAM_128 bouquets 
(that I'm whatching) are above that, e.g. in the range of 283MHz. So the 
offset might also be related to the freq rather than the modulation (which 
would make more sense to me).

All I can say for sure is that I have offset the QAM_64 bouquet by -125kHz 
and all the QAM_128 bouquets by -250kHz and all channels work perfectly. 
Before I applied the offset 80% of my channels switches across bouquets 
failed.

-- 
  Lauri


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