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

Andrew de Quincey adq_dvb at lidskialf.net
Tue Jun 7 21:59:49 CEST 2005


On Tuesday 07 June 2005 20:31, Oliver Endriss wrote:
> Andrew de Quincey wrote:
> > Just a thought - could it be the DiSEQC? I'm just using simple
> > tone/voltage control myself. Do all these cards use the same LNB chip on
> > them? The DVB-S stv0299 ones I have here all seem to use an LNBP16A chip.
>
> Cable ok? Loss of frontend power will reset the switch.
>
> It _might_ be possible to produce bogus Mini-A or Mini-B commands
> on the cable if the 22kHz tone gets interrupted for some reason
> (noise on the cable).
>
> Retuning would fail, since the DiSEqC commands will not be repeated.

Thats an interesting idea.. However at all but one site our switches are the 
dumbest ones possible (on purpose). They only support tone/voltage 
switching... so that should just keep signalling even if the cable is 
disconnected and reconnected.

At the remaining site the switches do have tone burst support - I'll look into 
resending that. It would be very simple to add resending of simple tone burst 
commands during a retune-due-to-signal-loss to the drivers. 

The problem affects some sites with the dumb switches as well though...




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