Toshiba Strata DK40 - Page 128

DK40 Universal Slot PCBs Timing and Synchronization
3-38
Strata DK40 I&M Manual Spring 1999
Refer to the Strata DK40 Programming Manual or DK Library CD-Rom for more details.
there is another PRI or BRI installed in the DK40. The Secondary reference PCB is assigned
in Program *42-2.
Figure 3-19 Primary and Secondary References
Figure 3-19 shows the Primary reference PCB. The clock signal from circuit 1 passes through
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). Figure 3-19 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.
2757
PDKU
Primary Reference PCB*
Secondary Reference PCB*
Other RPTU, RBSU or TBSU
DK40 Digital Transmission Voice Path
Synchronization
Circuit
Synchronization
Circuit
Synchronization
Circuit
Digital Voice
Path
Digital Voice
Path
Digital Voice
Path
DK40
Digital
Telephone
Electronic
Telephone
Standard
Telephone
SS
1
SS
2
SS
3
Line 1
Line 2
Line 3
British Telecom
ISDN
PRI or BRI
AT&T or
other provider
PRI or BRI
Other
PRI or BRI
provider
Clock
Source
-1
Base KSU (CTU PCB)
Clock not synchronized properly
Clock Source 1
Time
Switch
Clock
Synchronization
Circuit
Prg *42-1
Prg *41-1[blank]
Prg *42-2
Prg *42-2[blank]
Clock synchronized properly
Clock Source -1
Clock
Source
-Other
RSTU
PEKU
* Primary/Secondary reference PCBs
are assigned in Program *42-1/*42-2
and can be an RPTU,
RBSU, or TBSU.