[linux-dvb] FE_READ_BER and FE_READ_UNCORRECTABLE might be swapped for stv0299

Andrew de Quincey adq_dvb at lidskialf.net
Tue Aug 16 01:49:38 CEST 2005


On Sunday 14 Aug 2005 12:54, Johannes Stezenbach wrote:
> On Sat, Aug 13, 2005 Jeremy Hall wrote:
> > Is it possible that FE_READ_BER and FE_READ_UNCORRECTABLE might be
> > swapped for stv0299?
> >
> > I'm looking at a transport and the uncorrectable blocks are much higher
> > than the BER blocks.  Is this expected behavior?
>
> By definition BER is an error rate (i.e. number of wrong bits
> per 10^x received bits, with x typically = 12..18), which
> UNC is an absolute count of errored TS packets since
> the last call to FE_READ_UNCORRECTABLE.
>
> However, the stv0299 cannot measure both, so what Andrew
> implemented is rather crude: switch the error mode and
> block 100msec and return an absolute count in both cases.
>
> Which means that the number of wrong bits per 100msec
> before error correction should be higher than the
> number of errored packets per 100msec after error correction.
>
> Maybe Andrew can comment on this, I would guess that switching
> the error mode doesn't reset the error counter, and a dummy
> read needs to be added.

Yeah, it should really block for a calculated time depending on the error 
accumulation settings. I don't have the time to do this properly right now. I 
can revert the change if you want.




More information about the linux-dvb mailing list