Nortel Circuit Card 311 Reference page 906

906 NTAK20 Clock Controller daughterboard
The NTAK20 clock controller card can support 1.5 Mb, 2.0 Mb, and 2.56 Mb
clock recovery rates.
IMPORTANT!
Each Media Gateway that has a digital trunk must have a clock controller clocked
to an external reference clock.
The clock controller circuitry synchronizes the CS 1000 system to an
external reference clock and generates and distributes the clock to the
system. The CS 1000 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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Clocking modes
The clock controller can operate in one of two modes: tracking or
non-tracking (also known as free-run).
The clock controller can operate in one of two modes: tracking or
non-tracking (also known as free-run).
The CS 1000 supports a single clock controller that can operate in one of
two modes: tracking or non-tracking (also known as free-run).
Copyright © 2003-2008, Nortel Networks
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Note: Clocking slips can occur between Media Gateways 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
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
ATTENTION