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

Manu Abraham manu at kromtek.com
Thu Jun 9 15:56:46 CEST 2005


Andrew de Quincey wrote:
> On Wednesday 08 June 2005 23:04, Andrew de Quincey wrote:
>>>Incidentally, my latest test was to set the tone every 60 seconds in the
>>>frontend loop. This didn't work though - it still lost the lock, and went
>>>into the patch I posted earlier and regained it simply by setting the
>>>tone.
>>My mistake - there was a bug in this code which meant it wasn't actually
>>doing the above. I've corrected it and am waiting to see if it still loses
>>the lock.
> 
> Nope - its just lost it and ran the auto-regain-by-setting-tone code.
> 
> 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.
> 

I will verify this on Wednesday or Thursday when i am back. Maybe 
somebody else too can verify it in the meantime ..


Manu




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