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

Johannes Stezenbach js at linuxtv.org
Thu Jun 9 01:32:45 CEST 2005


On Thu, Jun 09, 2005 at 12:21:16AM +0100, Andrew de Quincey wrote:
> > So to summarise my current findings:
> > *) Setting the tone every 60 seconds does not help.
> > *) Setting the tone when the lock is lost causes it to be regained in under
> > 100ms.
> > *) If you don't set the tone/reg0x08 on lock loss, you will never regain
> > the lock.
> > *) The contents of register 0x08 of the stv0299 stay constant.
> > *) It cannot be noise/traffic on the i2c bus changing other registers since
> > the only thing needed to fix the issue is to set register 0x08 again.
> > *) No i2c traffic to the stv0299 besides reading the lock status occurs
> > after the initial tuning attempt.
> > *) Only a few cards are affected. Cards tuned to the same channels on other
> > sites are fine. Cards using the same multiswitch at the same site are fine.
> > *) At a site with the issue, channels can be manually reassigned between
> > cards/machines until a stable situation is found. This is very time
> > consuming though.
> > *) Temperature is unlikely to be a cause.
> > *) This problem occurs across a whole range of stv0299 based cards (we have
> > several vintages of them from the last few years).
> > *) There is no pattern temporally to the lock loss.
> > *) The problem occurs across different multiswitches by different
> > manufacturers.
> > *) The signal is perfect (BER==0) up until the time the lock is lost.
> > *) The problem _may_ affect stv0299 based Twinhan cards as well, but this
> > needs verified.
> 
> Another one:
> 
> *) It is not interference from other DVB cards in the same machine - the 
> machine I am testing stuff on only has one DVB-S card in it (and it doesn't 
> have any DVB-T cards in it either).

Maybe some dried up electrolytic capacitor making it
senstive to small power drop outs, like in:
http://defiant.wavecon.de/~alex/dvbbug/dvbbug.html

Johannes




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