363-206-295
Circuit Pack Descriptions
7-24 Issue 1 December 1997
Note: Distance in feet for 22 gauge PIC (ABAM) cable.
Figure 7-9. TG Option Switches for DDM-2000 OC-3 (Sheet 2 of 2)
TG Quick Reference Summary 7
Provisioned Modes 7
The TG circuit pack can be provisioned through on-board option switches to any one of
three timing modes: (a) External timing mode (b) Line (formerly loop) timing mode or (c)
Free-running mode.
In addition, the BBF2B TGS circuit pack can be provisioned through on-board option
switches to provide a DS1 output for network timing distribution or for shelf timing
distribution. Line (formerly loop) timing from the main OC-12 line is the factory default.
Holdover Mode 7
The holdover mode maintains the last good reference frequency during unprotected
failure of external or line (formerly loop)-timing references.
Maintenance and Control 7
The following maintenance functions are provided on the TG circuit pack: (a) DS1
reference monitoring, (b) TG and OLIU circuit pack protection switching, and (c) inventory
information (
CLEI
code, date of manufacture, etc.).
DS1 Output 7
— DS1 Output (MULT) — a buffered copy of the external DS1 input reference used
for intershelf timing
— DS1 Output (SYNC OUT) — derived from received OC-3 line for network timing
distribution.
Equalizer Switch Settings
Equalization (Note) S2-1 S2-2 S2-3
0' to 131' ON ON OFF
131' to 262' ON OFF ON
262' to 393' ON OFF OFF
393' to 524' OFF ON ON
524' to 655' OFF ON OFF
Invalid OFF OFF OFF
Invalid OFF OFF ON
Invalid ON ON ON
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