ZyXEL Communications MSC1024G Series User Manual page 177

Figure 92 LDM Test
The following table describes the labels in this screen.
Table 55 LDM Test
LABEL
LDM Test
Items
End
Get LDM Graph
MSC1000G/1024G/1224G Series User's Guide
DESCRIPTION
Select slot and port numbers from the Slot and Port drop-down list boxes and
click Set LDM Port to perform loop diagnostics on the specified port. Only slots
with an active ADSL line card display in the Slot drop-down list box. The ADSL
port must be set to ADSL2 or ADSL2+ ADSL operational mode and have a
connection. It takes about one minute for the loop diagnostics to finish.
Note: Wait at least one minute after using Set LDM Port before
using Get LDM Data.
After you use Set LDM Port, select a type of test results to display
result: Displays the basic loop diagnostic mode test results.
hlin: Displays the channel characteristics function represented in linear format by
a scale factor and a complex number. These are the maximum upstream and
downstream scale factors used in producing the channel characteristics function.
hlog: Displays channel characteristics. The format provides magnitude values in
a logarithmic scale. This can be used in analyzing the physical condition of the
ADSL or VDSL line.
qln: Displays the Quiet Line Noise for a DMT tone is the rms (root mean square)
level of the noise present on the line, when no ADSL or VDSL signals are
present. It is measured in dBm/Hz. The QLN can be used in analyzing crosstalk.
snr: Displays the upstream and downstream Signal to Noise Ratio (in dB). A
DMT tone'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).
Then click Get LDM Data to display the loop diagnostics results. Use the loop
diagnostics results to analyze problems with the physical ADSL line.
Select Near to display results for the upstream traffic (coming from the subscriber
to the line card).
Select Far to display results for the downstream traffic (going from the line card to
the subscriber).
Click this to display the loop diagnostics results as a line graph.
Chapter 8 Diagnostic Screens
177