ADC MM702G, User Manual

Page: 70 / 168

Complete a DSL Advanced Configuration
62 MM701G and MM702G User Manual
Power Spectrum Distribution
The Power Spectral Density (PSD) plots the variations of signal power with signal
frequency for the G.shdsl transmission between the modem and the DSLAM or the
modem and another modem.
Symmetric PSD indicates that the PSD mask for both sides
of the transmission (the CO- and remote-side) are the same (symmetric).
Asymmetric PSD indicates that the PSD mask for both sides of the transmission
(the CO- and remote-side) are not the same (asymmetric). There are two unique
numeric values (
AsymmetricRate1 and AsymmetricRate2 ) used to determine the
asymmetric PSD mask based on the Annex A or Annex B standard that you selected
(see
page 60 ). AsymmetricRate1 is 784 kbps for Annex A and 2312 kbps for Annex B.
AsymmetricRate2 is 1552 kbps for Annex A and 2056 kbps for Annex B.
Both ends of the connection must be set for the same Symmetric or Asymmetric PSD.
The default is
Symmetric .
Bit Rate Mode
Bit rate mode indicates how the modem synchronizes with the device to which it is
attached in either a
Fixed or Adaptive mode. The default for the MM702G modem is
Fixed mode. The default for the MM701G modem is Adaptive mode.
• Fixed mode indicates that the modem will synchronize with the other end (a
DSLAM or another modem) at a fixed bit rate through negotiation. The modem
will synchronize at the best rate, up to the data rate specified (
page 61 ), that can
be achieved by both ends.
• Adaptive mode indicates that prior to modem negotiating a rate, the modem
performs an adaptation phase during which it determines a best possible rate based
on conditions of the line. After adaptive mode, the modem will then negotiate the
best rate that can be achieved with the other end, based on the adaptation results.
An MM702G in
Dual Wire Pair Mode
cannot be used in
Adaptive Bit Rate Mode
.
Test Bit Rate
This bit rate is used by the manufacturer for internal use only.
SNR Margin Limit
Identifies the minimum SNR margin (in decibels) that must exist when the G.shdsl
connection is synchronized and in order for the DSL MAR LED to be lit ON Green.
The range of values is -64 to 63. The default value is 4.
3 Click
Apply
then save changes using “Saving Changes” on page 53 .