Nortel Circuit Card 311 Reference page 904

904 NTAK20 Clock Controller daughterboard
IMPORTANT!
Each Media Gateway that has a digital trunk must have a clock controller clocked
to an external reference clock.
If an IP Expansion multi-cabinet system is equipped with digital trunk cards, it is
mandatory that at least one trunk card is placed in the Main cabinet.
The clock controller circuitry synchronizes the system to an external
reference clock and generates and distributes the clock to the system.
The system can function either as a slave to an external clock or as a
clocking master. The NTAK20AD version of the clock controller meets the
AT&T Stratum 3 and Bell Canada Node Category D specifications. The
NTAK20BD version meets CCITT Stratum 4 specifications.
The NTAK20 card performs the following functions:
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The NTAK20 clock controller daughterboard mounts directly on the following
cards:
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Copyright © 2003-2008, Nortel Networks
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Note: Clocking slips can occur between systems that are clocked from
different COs, if the COs are not synchronized. The slips can degrade
voice quality.
phase lock to a reference, generation of the 10.24 Mhz system clock,
and distribution of the clock to the CPU through the backplane
accept one primary and one secondary reference
primary-to-secondary switchover and auto-recovery
chatter prevention due to repeated switching
error-burst detection and correction, holdover, and free running
capabilities
communication with software
jitter filtering
use of an algorithm to detect crystal aging and qualify clocking
information
"NTAK09 1.5 Mb DTI/PRI card" (page 859)
"NTBK50 2.0 Mb PRI card" (page 967)
"NTBK22 MISP card" (page 961)
"NTRB21 DTI/PRI/DCH TMDI card" (page 1053)
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
ATTENTION