[linux-dvb] GUI version of tzap

Petr Nejedly P.Nejedly at sh.cvut.cz
Wed Dec 7 12:22:24 CET 2005


Andy Burns wrote:

> see http://adslpipe.co.uk/linuxhtpc/images/gtzap1.png

Just a little note: BER is a Bit Error Ratio and should be the number of 
corrected bad bits.
Some drivers report vitterbi error rate (number of soft error recognized 
in the vitterbi decoder),
while some report reed-solomon error rate, that is the number of wrong 
bits on the input
of the reed-solomon decoder (while there were no uncorrected blocks).

It's a pity that the drivers mostly report an actual number of error bits
over unspecified (and maybe variable) time span.
It would be much better if the API required reporting real BER (R=ratio),
that is, the ratio between wrong bits and all bits received (over a 
reasonable period,
like 0.5s).
In that case the user would immediatelly recognize whether the signal is bad
or already good enough. It is said that DVB's RS corrector can produce
a "quasi-error free" output (i.e. very low probability of uncorrected block)
in case the BER is below 1*10^-4 (a most 1 bad bit in 10.000 bits).
You coud even have a marker on the BER meter, denoting the 1E-4 BER mark.

Somebody correct me if I'm wrong.

Nenik




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