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Timing and Synchronization
7-36 Strata CTX I&M 06/04
The Strata CTX processor time switch is synchronized as the slave to the PRI, BRI, or T1 line
(Line 1 in Figure 7-31).
If a malfunction occurs and Primary reference synchronization is lost, the Strata CTX
automatically switches modes and synchronizes to the Secondary reference, provided that there is
another PRI, BRI, or T1 installed in the Strata CTX system.
Figure 7-31 Primary and Secondary References
Figure 7-31 shows the Primary reference PCB. The clock signal from Line 1 passes through the
PCB Software Switch (SS
1
) and the synchronization circuit of the RCTU PCB. The RCTU clock
passes the clock source through the time switch and synchronizes 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 synchronization circuit (SS
1
) and
closing the synchronization circuit (SS
2
). When this occurs, the digital voice or data path of the
Strata CTX is synchronized to the Line 2 clock source.
If the path is not synchronized to the Stratum – 1 clock source, calls connected through that path
experience “slipping” or “jitter” in the digital voice or data path (channels). Figure 14-7 shows an
unsynchronized signal from Line 3. The unsynchronized signal produces a clicking or popping
sound that is heard by the people connected through this path or causes data errors on data
transmissions.
5439
PDKU
Primary Reference PCB*
Secondary Reference PCB*
Other RDTU, RPTU, or RBSU
CTX Digital Transmission Voice Path
Synchronization
Circuit
Synchronization
Circuit
Synchronization
Circuit
Digital Voice
Path
Digital Voice
Path
Digital Voice
Path
Strata CTX
Digital
Telephone
Standard
Telephone
SS
1
SS
2
SS
3
Line 1
Line 2
Line 3
Public Switched
Telephone
Network (PSTN)
PRI, BRI, or T1
AT&T or
other provider
PRI, BRI, or T1
Other
PRI, BRI, or T1
provider
Stratum-1
Clock
Source
Processor PCB
Clock not synchronized properly
with Stratum-1 Clock Source
Time
Switch
Clock
Synchronization
Circuit
Clock synchronized properly
with Stratum-1 Clock Source
Other
Clock
Source
RSTU