Noise Margin (AKA Signal to Noise Margin or Signal to Noise Ratio)
Relative strength of the DSL signal to Noise ratio. The higher the
number the better for this measurement. In some instances interleaving
can help raise the noise margin to an acceptable level.
6dB or below is bad and will experience no synch or intermittent synch
problems
7dB-10dB is fair but does not leave much room for variances in conditions
11dB-20dB is good with little or no synch problems* (but see note below)
20dB-28dB is excellent
29dB or above is outstanding
Line Attenuation
Measure of how much the signal has degraded between the DSLAM and the
modem. This is largely a function of the distance from the exchange. The
lower the dB the better for this measurement.
20dB and below is outstanding
20dB-30dB is excellent
30dB-40dB is very good
40dB-50dB is good
50dB-60dB is poor and may experience connectivity issues
60dB or above is bad and will experience connectivity issues
Znaci, Noise Margin treba biti sto veci (od 11 dB navise), a Line
Attenuation treba biti sto nizi (od 20 dB nanize).
Lako je izracunati i koliko je kabela izmedju vaseg modema i centrale.
Svaki kilometar kabela povecava Line Attenuation za +13.63dB. Npr. ako
je vas Line Attenuation = 11 dB onda izmedju vas i centrale ima cca 800
metara kabela.
Evo pa nekima mozda pomogne