906 NTAK20Clock Controller daughterboard
The NTAK20clock controller card can support 1.5 Mb, 2.0 Mb, and 2.56 Mb
clock recovery rates.
ATTENTION
IMPORTANT!
Each Media Gatewaythat has a digital trunk must havea clock controller clocked
to an external reference clock.
Note: Clocking slips can occur between Media Gateways that are
clocked from differentCOs, if the COs are not synchronized. The slips
can degrade voice quality.
The clock controller circuitry synchronizes the CS 1000 system to an
external reference clock and generates and distributes the clockto the
system. The CS 1000 can function either as a slave to an external clock or
as a clocking master. The NTAK20AD versionof the clock controller meets
the AT&TStratum 3 and Bell Canada Node Category D specifications. The
NTAK20BDversion meets CCITT Stratum 4 specifications.
The NTAK20card performs the following functions:
•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
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).
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
Copyright© 2003-2008, Nor tel Networks
.