Toshiba STRATA DK14 Installation And Maintenance Manual page 690

ISDN Interfaces
Timing and Synchronization
Digital
Telephone
Electronic
Telephone
Standard
Telephone
4773
Figure 16-31 Primary and Secondary References
Figure 16-31
the PCB Software Switch (SS
clock passes the clock source through the time switch and synchronizes the DK424 or DK424i
digital transmission voice or data path.
The Secondary reference is activated if the Primary reference fails. The DK424 or DK424i
automatically switches over to the Secondary reference PCB by opening its synchronization
circuit (SS
or data path of the DK424 or DK424i 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.
16-40
DK40i, DK424 or DK424i
Processor PCB
Synchronization
Circuit
Time
Switch
Clock
Primary Reference PCB*
PDKU
Synchronization
SS 1
PEKU
Digital Voice
RSTU
Secondary Reference PCB*
Synchronization
SS 2
Digital Voice
Other RDTU, RPTU, or RBSU
Synchronization
SS 3
Digital Voice
shows the Primary reference PCB. The clock signal from Line 1 passes through
) and the synchronization circuit of the RCTU PCB. The RCTU
1
) and closing the synchronization circuit (SS
1
* Primary/Secondary reference
PCBs are assigned in
Programs
can be an RDTU, RPTU,
RBSU, RBUU, TBUS or TBUU.
Line 1
Circuit
Prg *42-1-1
Path
Line 2
Circuit
Prg *42-2-2
Path
Line 3
Circuit
Prg *41-1[blank]
Prg *42-1[blank]
Path
Clock not synchronized properly
with Stratum-1 Clock Source
). When this occurs, the digital voice
2
42-1/ 42-2 and
* *
Public Switched
Telephone
Network (PSTN)
PRI, BRI, or T1
AT&T or
Stratum-1
other provider
Clock
PRI, BRI, or T1
Source
Clock synchronized properly
with Stratum-1 Clock Source
Other
Other
Clock
PRI, BRI, or T1
Source
provider
Strata DK I&M 6/00