System information

FCD 901 48
Issue R2A, 07.2009
XMP1 Release 5.5 System Description
Wander filter
Page 2-20 Proprietary Information Aastra
In order to use such clock sources for clock recovery in the local node, the
latter can be configured via the central card slot data (info no. 2) in such a
way that the local clock sources (T3in or ports with configured clock priority)
of this node are preferred.
With this configuration, the node then uses the configured local clocks
according to their clock priority. The clock priority received at the ports in bit
Y5 is not evaluated.
Only if these local clock sources have failed, clock priorities possibly
received at other ports in the service digits are used for clock control.
For this purpose, info no. 2 must be set to "1" in the central card slot data of
the Central Unit.
2.3.6.4 Wander filter
If several HDSL links are switched in series, the low-frequency jitter
(wander)) caused by the HDSL units can be reduced by setting info no. 10
to "1". The wander reduction, however, leads to an increased phase noise,
i.e. high-frequency jitter, which is filtered out again in the next node.
2.3.6.5 Using T3out
For the clock supply of external units, the Central Unit provides a clock
interface T3out. This T3out clock is distributed via the X6 connector of the
Central Unit. With the default setting, the system clock of the node is
provided under all operating conditions.
In case of failures, e.g. BER 10-3, loss of sync etc. at the port from which
the receive clock is recovered, the T3out clock can be switched off.
For this purpose, the following settings are possible in the Central Unit
(central card slot data) of the node:
Info no. 6:
Recover T3out from receive clock.
Info no. 5:
Switch off T3out in case of a port failure.