Sagem 4450E - Manual (Page 176)

SAGEM 3P@C
3P@C Installation Manual
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SAGEM SA
„ Echo
The echo is the reflection wave caused by the unbalance of line resistance or the bridge equipment in the line.
The echo would result in the loss of signal energy, and extra interference the line, especially greatly affecting the
full-duplex service transmission quality of broadband. The changes in the Line A-B capacitance and Line A/B-
ground capacitance and inter-line insulation resistance and ground insulation resistance will lead to the change
of line resistance to generate echo, and cause attenuation and interference to the VDSL signal. The use of
resistance matching technology and the echo elimination circuit can help reduce the affect of echo. The
resistance of VDSL to the transmission line is required to be the 100Ω pure resistor.
12.2.2. VDSL Line Commissioning
1.1.1.69 Connection, Configuration and Test of Office End Equipment
1) Connection of the VDSL equipment
Subscribers need to remove the original jumpers at the distribution frame upon applying for the commissioning of
VDSL service, and connect the distribution lines and jumpers again basing on the situation of the VDSL
equipment, to separate the traditional PSTN service from the data service, as shown in Figure 12-7.
Figure 12-6 VDSL distribution
Here:
„ P refers to the distribution frame of program-control switch
„ W refers to the PSTN distribution frame of the VDSL equipment
„ N refers to the subscriber line distribution frame for the VDSL equipment
2} VDSL parameter configuration
Based on the service types selected by subscribers, the ports related to the VDSL office end equipment should
be configured with the related parameters, including the VDSL upstream/downstream rates, auto-adaptation
mode, Ethernet rate and duplex mode. These parameters are relevant to the QoS and functions of subscribers.
3) Testing the VDSL connection parameters
After the VDSL equipment has finished with its jumper setting in the distribution room, the connection test needs
to be done in the actual environment, to ensure the commissioning of the VDSL service.