Toshiba Strata DK14 Installation And Maintenance Manual page 216

DK424 T1
RDTU T1 Interface Unit
Digital
Telephone
Electronic
Telephone
Standard
Telephone
1675
Notes
Primary Reference Synchronization:
In this diagram RDTU(1) is the primary reference, its synchronization circuit sends the clock
reference from the TELCO T1 span to the DK424, to the RCTU synchronization circuit, via
RDTU1 Software Switch (SS). The RCTU(1) clock synchronizes the DK424 digital
transmission voice path (via RCTU time switch) to the TELCO/STRATUM1 clock source.
Secondary Reference Switch-Over:
If the primary reference T1 RDTU(1) fails, the DK424 will automatically open the RDTU(1)
primary synchronization circuit (SS1) and close the RDTU(2) secondary synchronization
circuit (SS2). At this time, the DK424 digital voice path will be synchronized to the AT&T/
STRATUM1 clock source.
Slip example:
In the above diagram the "Other T1 Provider" is not synchronized to the STRATUM1 clock
source properly – Slip problems will occur on RDTU(3) T1 channels.
Figure 6-1 RDTU Primary/Secondary Reference Block Diagram
6-6
Strata DK424
RCTU PCB
Synchronization
Circuit
Time
Clock
Switch
PDKU
SS
1
PEKU
RSTU
SS
2
SS
3
RDTU(1) (Primary Ref)
Synchronization
Circuit
Digital Voice Path
RDTU(2) (Secondary Ref)
Synchronization
Circuit
Digital Voice Path
RDTU(3)
Synchronization
Circuit
Digital Voice Path
Span
Telco
Line 1
Central
Office
T1
Span
AT&T
Line 2
Stratum 1
Long
Clock
Distance
Source
T1
Span
Line 3
Other
T1
Provider
T1 Span Clock Not
Synchronized Properly with
Stratum 1 Clock Source
Strata DK I&M 5/99