Introduction 905
It is consequently located in slots 1 to 9 of the main and IP expansion
cabinets and can support 1.5 Mb, 2.0 Mb, and 2.56 Mb clock recovery rates
Note: The card is restricted to slots 1 through 3 in EMC- type cabinets
(such as NAK11Dx and NTAK11Fxcabinets). It does not work in slots 4
through 10 in these cabinets.
ATTENTION
IMPORTANT!
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 Option 11C cabinet.
A cabinet that has a digital trunk must have a clock controller.
NTAK20provides the following features and 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
•accepts 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 aid in detecting crystal aging and to qualify
clocking information
Digital trunking requires synchronized clocking so that a shift in one clock
source results in an equivalent shift in all parts of the network. In the CS
1000 system, synchronization is accomplished with an NTAK20clock
controller daughterboard in each Media Gateway that contains a digital
trunk card.
The NTAK20clock controller daughterboard mounts directly on the following
cards:
•NTAK091.5Mb DTI/PRI
•NTBK50 2.0 Mb PRI
•NTRB21 DTI/PRI/DCH TMDI
•NT6D70 SILC
•NT6D71 UILC
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
Copyright© 2003-2008, Nor tel Networks
.