Timing And Synchronisation - Toshiba Strara CTX Series Installation And Maintenance Manual

Timing and Synchronisation

In the Strata CTX, one PRI or BRI can be programmed to extract the Stratum clock signal. It uses the
signal as the Strata CTX system Primary clock reference. The clock provider should be a reliable
source, such as a network operator. All other PRI or BRI lines connected to the Strata CTX will be
synchronised to the same clock provider. If the PRI or BRI are not synchronised to the same clock
provider, the Strata CTX could experience "slip" problems.
The timing or synchronisation program determines how the Strata CTX digital voice or data
transmission path is synchronised with the far-end digital path. For proper PRI or BRI operation, the
equipment at each end of the line must be synchronised.
The Strata CTX processor time switch is synchronised as the slave to the PRI or BRI line (Line 1 in
Figure 5-20).
If a malfunction occurs and Primary reference synchronisation is lost, the Strata CTX automatically
switches modes and synchronises to the Secondary reference, provided that there is another PRI or
BRI installed in the Strata CTX system.
Digital
Telephone
Standard
Telephone
5439
Figure 5-20 Primary and Secondary References
Figure 5-20 shows the Primary reference PCB. The clock signal from Line 1 passes through the
PCB Software Switch (SS
passes the clock source through the time switch and synchronises the Strata CTX digital
transmission voice or data path.
The Secondary reference is activated if the Primary reference fails. The Strata CTX automatically
switches over to the Secondary reference PCB by opening its synchronisation circuit (SS
closing the synchronisation circuit (SS
Strata CTX is synchronised to the Line 2 clock source.
Strata CTX I&M September 2002
CTX
Processor PCB
Synchronisation
Circuit
Time
Switch
Clock
Primary Reference PCB*
PDKU
Synchronisation
SS 1
Digital Voice
RSTU
Secondary Reference PCB*
Synchronisation
SS 2
Digital Voice
Other RPTU or RBSU
Synchronisation
SS 3
Digital Voice
) and the synchronisation circuit of the RCTU PCB. The RCTU clock
1
Line 1
Circuit
Path
Line 2
Circuit
Path
Line 3
Circuit
Path
Clock not synchronised properly
with Stratum-1 Clock Source
). When this occurs, the digital voice or data path of the
2
ISDN Interfaces
Public Switched
Telephone
Network (PSTN)
PRI or BRI
BT or
Stratum-1
other provider
Clock
PRI or BRI
Source
Clock synchronised properly
with Stratum-1 Clock Source
Other
Other
Clock
PRI or BRI
Source
provider
) and
1
5-21