Timing And Synchronisation - Toshiba strata CT Installation & Maintenance Manual

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Timing and Synchronisation

The Digital Network is connected by timing clocks that synchronise the network and have
various degrees of precision (stratum levels). There are four stratum levels – 1 is the highest
and 4 is the lowest. They are associated with the following sources:
N
N
N
N
In the Strata CT, one PRI and BRI PCB can be programmed to extract the Stratum clock
signal. It uses the signal as the CT system Primary clock reference. The clock provider should
be a reliable source, such as a Telco or common carrier. All other PRI and BRI lines
connected to the Strata CT will be synchronised to the same clock provider. If the PRI and
BRI are not synchronised to the same clock provider, the Strata CT could experience "slip"
problems.
Timing reference assignments for PRI and BRI are made with the Program *42 series. The
timing or synchronisation program determines how the Strata CT digital voice or data
transmission path is synchronised with the far-end digital path. For proper PRI and BRI
operation, the equipment at each end of the line must be synchronised.
H
The CT processor time switch is synchronised as the slave to the PRI and BRI line (Line 1 in
Figure
reference (Program *42-1, DATA=1 for this PRI and BRI).
If a malfunction occurs and Primary reference synchronisation is lost, the Strata CT
automatically switches modes and synchronises to the Secondary reference, provided that
there is another PRI, BRI, or T1 installed in the CT system. The Secondary reference PCB is
assigned in Program *42-2.
C
10-22
Stratum – 1: Public Telephone Network clock
Stratum – 2: #4 ESS Toll Switches
Stratum – 3: #5 ESS Exchange Lines
Stratum – 4: Digital PBXs
10-17). The Strata CT PRI and BRI in any slot number can be assigned as the Primary
Strata CT I&M Manual October 2000