Specifications

Watson TDM
Operating Manual
Watson-TDM-Manual-W.doc
Version 2.0-01
3-4
Revision: 2008-02-07
3.1.5 Power Backoff
In order to reduce interference on other transmission systems operating on adja-
cent pairs bundled in the same cable, the DSL transmit power can be decreased
by activating the power back-off mode.
With enabled power back-off the transmit power will be reduced adaptively in
function of the estimated power loss i. e. the estimated cable attenuation:
Estimated Power Loss(*) Power Backoff
< 1 dB 6 dB
< 2 dB 5 dB
< 3 dB 4 dB
< 4 dB 3 dB
< 5 dB 2 dB
< 6 dB 1 dB
≥ 6 dB
no backoff
(*) Calculated as Tx Power – Estimated Rx Power
Table 3-4: Power Backoff
Activating the power backoff setting on one end of a DSL link causes the other
end of the link to reduce its transmit power.
Power backoff can be enabled individually for both ends of the link. Since the
STU-R always follows the configuration of the STU-C enabling power backoff on
the STU-C causes a symmetrical situation with STU-C and STU-R both using
power backoff:
STU-C
STU-R
Monitor setting
BACKOFF ON
in STU-C
Transmit power
STU-R --> STU-C reduced
Transmit power
STU-C --> STU-R reduced
Monitor setting
BACKOFF ON
in STU-R
Figure 3-1: Power backoff
There is no power backoff setting in regenerators. A regenerator is however ca-
pable of reducing its transmit power if the other end of the link has power backoff
enabled: