[linux-dvb] How does bad reception influence quality of macroblocks?

Morgan Tørvolt morgan.torvolt at gmail.com
Fri Feb 16 12:45:45 CET 2007


> I am a little puzzled as to why the second entry in your example is
> showing uncorrected errors and yet has a ber of 0.

Many (at least professional satellite modems) receivers calculate BER
rather than actually measuring them, and the other way around. The
theory is very clear here, and quite good in regards to real life
performance. If one have the Carrier to Noise level, one can calculate
the Eb/No value, which more or less directly translates to bit-error
rate. It goes the other way around also, so if you have the bit-error
rate you can calculate the CNR. (of course you have symbol-rate, fec
and the other parameters for the carrier)
This could cause the receiver to see the signal level as very good,
and calculate a good BER, but still the actual Reed Solomon/FEC error
correction will know that there where some errors there anyway because
of poor syncronization. One should never assume that things are all
good after only a few seconds.

That could be it. Could also very well not be. It could also be that
the BER and UNC reported are not for the same period of time.



More information about the linux-dvb mailing list