ZyXEL Communications MSC1000G Series, User Manual

Page: 166 / 1168

Chapter 6 Diagnostic Screens
Management Switch Card User’s Guide
166
6.2.1 Loop Diagnostics Test Parameters
Figure 89
LDM Test Result
The following table lists the loop diagnostics test parameters that display, see the ITU-T’s G.992.3
for more information.
6.3 Loopback Screen
Click Diagnostic > Loopback in the navigation panel to display this screen. Use this screen to
perform loopback tests.
Table 64
Loop Diagnostics Test Parameters
LABEL DESCRIPTION
near end (NE) This column of diagnostics results is for the upstream traffic (coming from the subscriber
to the IES).
far end (FE) This column of diagnostics results is for the downstream traffic (going from the IES to the
subscriber).
attainable bit rate
(kbps) This is the upstream and downstream attainable net data rate in Kilobits/s.
loop attenuation
(dB) This is the upstream and downstream line attenuation, measured in decibels (dB).
Loop attenuation is the difference between the power transmitted at the near-end and
the power received at the far-end. Loop attenuation is affected by the channel
characteristics (wire gauge, quality, condition and length of the physical line).
signal attenuation
(dB) This is the upstream and downstream signal attenuation (reductions in amplitude of the
DSL signal). It is measured in decibels (dB).
Signal attenuation is affected by factors such as noise, heat, crosstalk and loop
attenuation.
snr margin (dB) This is the upstream and downstream Signal-to-Noise Ratio margin (in dB). A DMT sub-
carrier’s SNR is the ratio between the received signal power and the received noise
power. The signal-to-noise ratio margin is the maximum that the received noise power
could increase with the system still being able to meet its transmission targets.
actual Tx Power FE
(dBm) This is the upstream and downstream far end actual aggregate transmit power (in dBm).