ZyXEL Communications IES-1248-71 User Manual page 270

Chapter 41 Diagnostic
Table 89 ToneDiag Parameters (continued)
LABEL
log(dB)
QLN(dBm)
SNR(dB)
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DESCRIPTION
This is a format for providing channel characteristics. It provides magnitude
values in a logarithmic scale. This can be used in analyzing the physical
condition of the ADSL line.
The Quiet Line Noise for a DMT sub-carrier is the rms (root mean square) level
of the noise present on the line, when no ADSL signals are present. It is
measured in dBm/Hz. The QLN can be used in analyzing crosstalk.
This is the upstream and downstream Signal-to-Noise Ratio (in dB). A DMT
sub-carrier's SNR is the ratio between the received signal power and the
received noise power. The SNR can be used in analyzing time dependent
changes in crosstalk levels and line attenuation (such as those caused by
temperature variations and moisture).
IES-1248-71/73 User's Guide