Chapter 28 Diagnostic
AMG1302-T11C User’s Guide
219
ATM Loopback
Test
Click this to start the ATM loopback test. Make sure you have configured at least one PVC
with proper VPIs/VCIs before you begin this test. The AMG1302-T11C sends an OAM F5
packet to the DSLAM/ATM switch and then returns it (loops it back) to the AMG1302-
T11C. The ATM loopback test is useful for troubleshooting problems with the DSLAM and
ATM network.
DSL Line Status Click this to view statistics about the DSL connections.
noise margin downstream is the signal to noise ratio for the downstream part of the
connection (coming into the AMG1302-T11C from the ISP). It is measured in decibels. The
higher the number the more signal and less noise there is.
output power upstream is the amount of power (in decibels) that the AMG1302-T11C is
using to transmit to the ISP.
attenuation downstream is the reduction in amplitude (in decibels) of the DSL signal
coming into the AMG1302-T11C from the ISP.
Discrete Multi-Tone (DMT) modulation divides up a line’s bandwidth into sub-carriers
(sub-channels) of 4.3125 KHz each called tones. The rest of the display is the line’s bit
allocation. This is displayed as the number (in hexadecimal format) of bits transmitted for
each tone. This can be used to determine the quality of the connection, whether a given
sub-carrier loop has sufficient margins to support certain ADSL transmission rates, and
possibly to determine whether particular specific types of interference or line attenuation
exist. Refer to the ITU-T G.992.1 recommendation for more information on DMT.
The better (or shorter) the line, the higher the number of bits transmitted for a DMT tone.
The maximum number of bits that can be transmitted per DMT tone is 15. There will be
some tones without any bits as there has to be space between the upstream and
downstream channels.
Reset ADSL Line Click this to reinitialize the ADSL line. The large text box above then displays the progress
and results of this operation, for example:
"Start to reset ADSL
Loading ADSL modem F/W...
Reset ADSL Line Successfully!"
Table 92 Maintenance > Diagnostic > DSL Line (continued)
LABEL DESCRIPTION
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