System information

FCD 901 48
Issue R2A, 07.2009
XMP1 Release 5.5 System Description
Functioning of the SETS
Aastra Proprietary Information Page 3-17
The SETG (Synchronous Equipment Timing Generator) receives the clock
from SELECT B and uses it to generate clock T0 required by the network
element itself and made available to the modules.
SELECT A passes on the clock to the adjustable "Autom. squelch" switch.
The latter decides whether the clock quality is sufficient and whether the
clock will be switched through to selector switch SELECT C. SELECT C
chooses the clock to be sent out at T4 (previously T3out). Both switches can
be adjusted at the Operator Terminal.
Clock T0 can also be used for clock recovery in the PDH kernel. Clock T0
is then routed from SETG to PET of the PDH section. If one of the XMP1
nodes recovers its clock from the SDH clock, this clock will still be
distributed in the network with priority 65535 via the 2MB ports of XMP1.