INSTALLATION
Page 30
DOC_DE_User guide_B
12.2
Crosstalk interference
If the cable is made of several pairs, each pair can be used to transmit a particular SHDSL connection ; however
the SHDSL signal transmitted in one pair may disturb the SHDSL signal transmitted in another one, and, in
some cases, may decrease the effective data rate of both SHDSL connections.
The closer the pairs, the greater the crosstalk. Thus the risk of crosstalk is higher between two pairs of the
same quad.
This is why, if the cable is made up of quads, it is advisable to avoid using the two pairs of the same quad.
12.3
Shield earthing
A shielded cable provides better noise immunity and surges protection during thunderstorms.
The best protection is provided when the shield is earthed at each end of the line.
However, there may be a large potential difference between the connection points to the earth, especially when
the line is long.
Therefore, to avoid a large current flowing in the shield, it is recommended to connect the shield to the earth
at only one end of the cable.
12.4
Protecting the SHDSL switch from lightning
The XSLAN+ is coupled to the line by a transformer which provides isolation between the circuit board and the
line. Moreover, the XSLAN+ is equipped with internal protections against overvoltage.
However, if the line is vulnerable to thunderstorms, for example if it is an air line, or if it is several kilometers
long, or if the installation is in a very exposed area, it is recommended to protect each XSLAN+ with a surge
protector, as described below.
13
Connecting the XSLAN+ to the line
13.1
General precautions
The SHDSL signal is not polarized ; it is why the two conductors of one line can be inverted.
Check that the shield, if any, is properly connected to the ground.
