[linux-dvb] Lost lock problems over extended periods of time

Andrew de Quincey adq_dvb at lidskialf.net
Wed Jun 8 17:36:13 CEST 2005

On Wednesday 08 June 2005 14:58, Manu Abraham wrote:
> Andrew de Quincey wrote:
> > On Wednesday 08 June 2005 10:13, Manu Abraham wrote:
> >>Andrew de Quincey wrote:
> >>>>>That is sort of what I was thinking in desperation and my first hack
> >>>>> :) The only thing it didn't do is set the tone/voltage settings again
> >>>>> - which may explain why the first hack didn't retune - thats what I'm
> >>>>> trying now - a combination of set tone/voltage plus reset & FE
> >>>>> settings.
> >>>>
> >>>>But i was thinking whether we would treating the symptom in that case
> >>>> .. I was wondering why the lock goes off at all in the first case ..
> >>>
> >>>Oh yeah, I agree the hack is doing stuff with the symptoms - I'm just
> >>>trying to identify what fixes it so we can track down the cause.
> >>>
> >>>Do the multiswitches where you saw the problem support anything about
> >>>tone/voltage switching BTW?
> >>
> >>No switches.. connected directly..
> >>DVB-Card-->Splitter-->Amplifier-->LNB.
> >>
> >>The amplifier was there because of a long RG-11 cable.. The Amplifier
> >>was near the LNB (approx 10m away, to reduce input noise)
> >
> > Hi, I've managed to get it to auto-retune. However it is very weird....
> > All I've done is the following in the else clause of "if (s &
> > FE_HAS_LOCK)":
> Originally as per the DVB API the default behaviour was to auto tune if
> there was a loss of lock (?)
> I think somebody (Johannes ?) a while stated that i was a bug that
> caused it not to retune..
> So i believe you hit that bug instead.. Sometimes it so happens that
> searching for something else you find something else..

I'm fairly sure it retunes when it loses the lock - in the current code it 
enters the FESTATE_ZIGZAG_FAST state if it loses the lock - which will kick 
off the zigzag scan from the place it left off the first time.

I know it does in fact - try unplugging a DVB-T aerial cable from a tuned 
card, and then plugging it back in after a while - it will relock when you 
restore it.

Secondly, my first test - that forced it to retune when the lock was lost, and 
that did not work.

Anyway, I'm _not_ retuning just now - all I'm doing is setting the 
tone/voltage to what they were before, and it comes back perfectly. 

I'm just waiting for it to die again to find out whether it is the setting of 
the voltage, the tone, or both that is needed to fix it. 

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