Specifications

Watson TDM
Operating Manual
Watson-TDM-Manual-W.doc
Version 2.0-01
4-2
Revision: 2008-02-07
4.3 Cascading
The Watson TDM Regenerator can be cascaded to form long links. The maxi-
mum allowed length of a link is 9 spans, i.e. 8 regenerators in series:
...
LTU
DSL A
DSL B
C-Side
(STU-C)
R-Side
(STU-R)
REG
1
Remote Power
Remote Terminal
connection
CON 3 CON 4
CON 2 or
CON
REG
2
NTU
REG
8
CON 10
Local Power
Figure 4-2: Cascading and addressing regenerators
4.4 Powering
The Watson TDM Regenerator can be powered locally or remotely.
A local DC power source can be connected to the regenerator directly, see 9.7.
The alternative is to use remote powering from the LTU. Both local and remote
powering can be present simultaneously. No powering configurations have to be
done in the regenerator.
Warning
The local powering inputs are galvanically connected to the DSL wire pairs.
Power supplies used for local powering must be certified according to EN
60950-1.
If a battery is used for local powering then all other devices connected to this
battery must be protected against overvoltage from the DSL wire pairs.
Installation of the local powering circuitry from the power supply or the battery
must ensure that it is not possible to touch any conductive parts of the installa-
tion that are connected directly or indirectly with the local powering inputs.
The distance achievable with remote powering depends on both the cable char-
acteristics (ohmic resistance) and the number of remotely powered nodes (re-
generators and the NTU). As a general rule one node can be remotely powered
per wire pair, i.e. one regenerator or the NTU on a single-pair system and two re-
generators (or one regenerator and the NTU) on a two-pair system. For longer
links both the NTU and the regenerators must powered be locally.
Two factors limit the powering distance:
• The regenerator requires a minimal voltage (57 VDC) at its input for proper
operation
• The feeding current per pair is limited by the LTU to comply with relevant
safety requirements (the DSL link is classified as a TNV-3 circuit according to
EN 30069.