ZyXEL Communications MSC1000G User Manual page 165

Figure 88 LDM Test
The following table describes the labels in this screen.
Table 63 LDM Test
LABEL
LDM Test
Items
End
Get LDM Graph
Management Switch Card 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 6 Diagnostic Screens
165