Hi Wolfgang, > the SNR value is only dependent on the demodulator you use, so even with > a different frontend, the values can be directly compared as long as you > use the same demodulator IC (and firmware, maybe...). > For most demodulators, you can give a (more or less) simple equation to > calculate the S/N (or C/N, whatever you want to call it) from the register > values, but unfortunately there are some exceptions: STV0297 DVB-C for > example. You are right. What I said was very wrong. I did think correctly though, I was just thinking without writing it down =) What I meant to say was, that even with the same frontend, two cards synced on the same signal from the same antenna could have different snr as a result of the sensitivity of the tuner and possibly also the shielding and the noise coming from the tuner and the signal amplifier itself. That said, the snr is probably the best data you have on the quality. Unfortunately devices like avemerdia volar A808 (I have one of those) does not give you snr at all. That is very unfortunate. In such a case the best thing for the driver to do is to calculate the snr from the ber. It will not be accurate though. >From a professional point of view, the actual BER could be the most important one, but also that is implemented differently, probably in hardware as well as in the drivers. > The signal strength, in turn, is most often not even useful when comparing > devices of the same type - the tolerances are too big, you can only get > a rough idea of "any signal present" or "no signal present". (Which is, > BTW, sometimes very nice too have, too.) Absolutely! > Regards, > Wolfgang -Morgan- _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
