Toshiba Strata CT, Installation & Maintenance Manual

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ISDN Interfaces
Strata CT I&M Manual October 2000
10-23
Figure 10-17 Primary and Secondary References
Figure 10-17 shows the Primary reference PCB. The clock signal from Line 1 passes
through the PCB Software Switch (SS1) and the synchronisation circuit of the RCTU
PCB. The RCTU clock passes the clock source through the time switch and
synchronises the Strata CT digital transmission voice or data path.
The Secondary reference is activated if the Primary reference fails. The Strata CT
automatically
switches over to the Secondary reference PCB by opening its
synchronisation circuit (SS1) and closing the synchronisation circuit (SS2). When this
occurs, the digital voice or data path of the Strata CT is synchronised to the Line 2 clock
source.
If the path is not synchronised to the Stratum – 1 clock source, calls connected through
that path experience “slipping” in the digital voice or data path (channels).
Figure 10-17
shows an unsynchronised signal from Line 3. The unsynchronised signal produces a
clicking or popping sound that is heard by the people connected through this path or
causes data errors on data transmissions.
4773
PDKU
Primary Reference PCB*
Secondary Reference PCB*
Other RPTU or RBSU
Str
ata CT Digital
T
ransmission
V
oice P
ath
Synchronisation
Circuit
Synchronisation
Circuit
Synchronisation
Circuit
Digital Voice
Path
Digital Voice
Path
Digital Voice
Path
Strata CT
Digital
Telephone
Electronic
Telephone
Standard
Telephone
SS1
SS2
SS3
Line 1
Line 2
Line 3
Public Switched
Telephone
Network (PSTN)
PRI and BRI
BT or
other provider
PRI and BRI
Other
PRI and BRI
provider
Stratum-1
Clock
Source
Processor PCB
Clock not synchronised properly
with Stratum-1 Clock Source
Time
Switch
Clock
Synchronisation
Circuit
Prg *42-1-1
Prg *41-1[blank]
Prg *42-2-2
Prg *42-1[blank]
Clock synchronised properly
with Stratum-1 Clock Source
Other
Clock
Source
RSTU
PEKU
* Primary/Secondary reference
PCBs are assigned in
Programs
*
42-1/
*
42-2 and
can be an RPTU or RBSU.
H
C