On Sat, 2012-04-28 at 14:36 -0400, Brian J. Murrell wrote: > One more question... > > On 12-04-28 10:56 AM, Andy Walls wrote: > > > > So I see SNR values from 0x138 to 0x13c ( 31.2 dB to 31.6 dB ) when you > > have problems. For 256-QAM cable signals, I think that is considered > > marginal. > > I've never gotten my mind around SNRs and dBs, etc. Generally speaking, > am I looking for these "snr" values to go up or down (i.e. closer to 0 > or further away) to make my signal better? Higher SNR is better: Higher SNR => lower probability of bit errors Lower SNR => higher probability of bit errors SNR in dB = 10 log (S/N) S : Received signal power in Watts N : Noise power at measurement point in Watts A logarithmic scale (dB) is used to express the quantities in values that are easier for people to comprehend and deal with. Gains and losses in dB are additive. -3 dB corresponds to a drop by a factor of 1/2: 10 * log(1/2) = -3.01 +3 dB corresponds to a gain by a factor of 2: 10 * log(2) = 3.01 Regards, Andy > Cheers, > b. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
