[linux-dvb] Initial tuning data for Hastings, UK, transmitter

Christoph Pfister christophpfister at gmail.com
Wed Sep 12 12:39:43 CEST 2007


Am Mittwoch 12 September 2007 schrieb nigeltamplin at f2s.com:
> Quoting Christoph Pfister <christophpfister at gmail.com>:
> > Hi,
> >
> > Am Dienstag 04 September 2007 schrieb nigeltamplin at f2s.com:
> > > Hello,
> > >
> > > I created the below initial tuning data file for the Hastings, UK,
> > > transmitter. I used information from this web-page
> > > http://www.ukfree.tv/txdetail.php?a=TQ806100
> > >
> > > It works ok for me.  Can / should someone add this file to the main
> > > repository?
> >
> > Adding it, thanks :)
> >
> > Note: according to
>
> http://www.ofcom.org.uk/static/reception_advice/digital_trans_guide/show_tr
>ansmitter.asp-siteID=71.html
>
> > some of the frequencies use a negative offset (-167khz) - can you please
> > check whether the corrected version still works as expected?
>
> Would this explain why the output of scan lists most channels twice?

Yes ...

<snip>

> A difference of -166.670khz.
>
> How does scan know to check 553833330 when only 554000000 is in the initial
> tuning data file?  I have also noticed that if I only specify one frequency
> in the initial tuning data file scan finds all the other frequencies and
> all the channels, is this by the same method?

The stream contains information where to find the other transponders (just 
that you can't really rely on it as it's sometimes wrong).
So 554 comes from the initial scan file and 553.833 from the network 
information tables in the stream.

> Furthermore both
> $ dvbstream -f 554000 600 601
> and
> $ dvbstream -f 553833 600 601
> Work for BBC ONE.
>
> So now that I have two frequencies I can use for most channels I wonder
> which I should use?  Is there any advantage of one over the other?  Why
> broadcast the same stream twice?

It's only broadcasted once (on 553.833). But many cards / drivers 
(unfortunately not all, that's why I committed a corrected version) can still 
find the transponder if the supplied frequency is somewhat near the real 
frequency.

> Regards,
>
> Nigel

Christoph



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