A-24 Issue 4 February 1997
363-208-011
Applications
Network Synchronization
DS1 Timing
The SONET standard requires that the
SLC
-2000 system be integrated into the
digital synchronization network. The network will be synchronized to a local
central office clock via DS1 external synchronization references. The
SLC
-2000
COT accepts two external DS1 synchronization references (one primary and one
secondary from the local clock which must be Stratum 3 or better, with timing
traceable to a Primary Reference Supply.
For Remote Site 2 the example depicted in Figure A-10 shows the far-end RT
terminal recovering the timing signal from the incoming OC-3 line (loop-timed).
Remote Site 1 is configured to provide a sync output for the Building Integrated
Timing Supply (BITS) clock and the TGS circuit packs are externally timed to the
DS1 reference. This arrangement must utilize the special ED8C724-20 G-394
Sync Input Timing Cable in series with the incoming Reference Timing Cable
ED7C723-37, G27–29 or ED8C724-20 G339–341. This special cable prevents a
timing loop when the TGS pack supplying a DS1 timing output is removed.
Figure A-10 also shows the cabling for multiple bays within the Central Office site.
Composite Clock
The DLC section of the
SLC
-2000 system requires 8/64 kHz composite clock
connections for Dataport, ISDN, etc. service. The composite clock source can be
the Synchronization Distribution Expander (SDE) which takes the DS1 timing
reference from a Stratum 3 or better source. The SDE must be traceable to the
same Primary Reference Source (PRS).
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