Toshiba Strata DK40 Installation & Maintenance Manual page 128

DK40 Universal Slot PCBs
there is another PRI or BRI installed in the DK40. The Secondary reference PCB is assigned
in Program *42-2.
Clock
Digital
Telephone
PDKU
Electronic
PEKU
Telephone
Standard
Telephone
RSTU
2757
* Primary/Secondary reference PCBs
are assigned in Program *42-1/*42-2
and can be an RPTU,
RBSU, or TBSU.
Figure 3-19
Figure 3-19
the PCB Software Switch (SS 1 ) and the synchronization circuit of the CTU PCB. The CTU
clock passes the clock source through the time switch and synchronizes the DK40 digital
transmission voice or data path.
The Secondary reference is activated if the Primary reference fails. The DK40 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 DK40 is synchronized to the circuit 2 clock source.
If the path is not synchronized to either the Primary or Secondary clock source, calls
connected through that path experience "slipping" or "jitter" in the digital voice or data path
(channels).
signal produces a clicking or popping sound that is heard by the people connected through
this path or causes data errors on data transmissions.
3-38
Refer to the Strata DK40 Programming Manual or DK Library CD-Rom for more details.
DK40
Base KSU (CTU PCB)
Synchronization
Circuit
Time
Switch
Primary Reference PCB*
SS 1
Secondary Reference PCB*
SS 2
Other RPTU, RBSU or TBSU
SS 3
Primary and Secondary References
shows the Primary reference PCB. The clock signal from circuit 1 passes through
Figure 3-19 shows an unsynchronized signal from Line 3. The unsynchronized
Synchronization
Circuit
Prg *42-1
Digital Voice
Path
Synchronization
Circuit
Prg *42-2
Digital Voice
Path
Synchronization
Circuit
Prg *41-1[blank]
Prg *42-2[blank]
Digital Voice
Path
Timing and Synchronization
British Telecom
Line 1
ISDN
PRI or BRI
AT&T or
Line 2
other provider
PRI or BRI
Clock synchronized properly
Clock Source -1
Line 3
Other
PRI or BRI
provider
Clock not synchronized properly
Clock Source 1
Strata DK40 I&M Manual Spring 1999
Clock
Source
-1
Clock
Source
-Other