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Circuit Pack Descriptions
7-16 Issue 1 December 1997
Synchronization 7
Synchronization Functions 7
The DDM-2000 OC-12 Multiplexer supports three synchronization modes:
1. DS1 timing input from stratum 3 or better office clock for CO applications
2. Free-running in CO applications when external timing inputs are not
available
3. Line (formerly loop) timing for remote timing functions.
In addition, the BBF2B/BBF4 TGS/TG3 circuit pack provides a DS1 timing output
that is used for network synchronization and allows line (formerly loop) timing and
DS1 Output timing to be derived from the main OLIUs.
The timing circuit packs distribute clock and frame signals, derived from the
selected reference source, to the transmission circuit packs.
BBF2B/BBF4 TGS/TG3 Circuit Pack Description 7
Purpose of Circuit 7
The synchronous timing generator (TG) circuit pack provides timing for the shelf.
Other functions include a derived DS1 output for use as a reference signal by a
building integrated timing supply (BITS) or a DS1 MULT capability for
synchronizing other shelves in the bay. The derived DS1 is traceable to timing
from the main OLIUs.
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