From: Hendrik Sattler <ubq7@st...> - 2005-05-22 00:22:03
Am Samstag, 21. Mai 2005 20:34 schrieb J=FCrgen Kofler:
> I have a question: In the channels dialog panel of Kaffeine one will
> =A0find a signal meter and a signal to noise ratio meter.
> =A0I only know of SNR meters showing db values. What does it mean, if
> =A0SNR is 71% for example? 71% of what? ;)
SNR =3D signal/noise
You can measure in in dB or not, dB simply means
SNR[dB] =3D 10 * SNR[B] =3D 10 * lg(SNR)
Since they probably measure powers: SNR[dB] =3D 20 * lg(signal[V]/noise[V])
Wikipedia is very informative about this.
> =A0Same goes for the signal meter. I get =A07%. What does it mean? What is
100% is the expected maximum power for DVB-T. You'll surely never get that.
> =A0I am a little confused, since I get "only" 7% signal but 71% SNR....
71/100 =3D (7/100) / x
<=3D> x =3D 7/(71*100) ~=3D 0,1%
You don't have a strong signal but not much noise either :)