[linux-dvb] Re: Question about inversion and DVB-S

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

On Monday 01 March 2004 21:49, w-thiel@gmx.net wrote:
> Hi,
>
> On Mon, Mar 01, 2004 at 01:02:19PM +0000, Andrew de Quincey wrote:
> > Hi, I've just encountered something very weird about frequency inversion.
> > With my new stv0299 code, I'm able to get a much better signal for lots
> > of channels. Except one. 11747000 on hotbird (EDTV Dubai etc). This is
> > with inversion turned OFF BTW.
> >
> > With the new code I'm not able to lock on 11747 at all. But.. as I was
> > despairing of things to try, I tried turning inversion ON. Now I can lock
> > on to that signal perfectly (but none of the others, 'cos they require
> > inversion OFF).
>
> According to my rev. 1.3 ff card, this transponder uses inversion=on.
> I also have to use a symbolrate of 27504: I don't get a lock at 27500.

Aha! So you have the same thing; inversion is ON for that channel.

The frontend on mine can get a lock at 27500, but I'd noticed when I read the 
values back from the hardware that it had actually detected 27504.. What 
frontend is on your card BTW?

Another thing is that 11747000 is _really_ close to the lnb switch frequency 
of 11700000.. could that have something to do with it I wonder?

Is there any actual point in being able to specify the inversion then? It 
sounds like we should always be using INVERSION_AUTO to ensure we don't get 
these problems.


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