Page504 of 544 NTAK20clock controller
553-3011-100 Standard14.00 January 2002
•NTBK22 MISP card (page261)
•NTRB21 DTI/PRI/DCH TMDI card (page461)
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 NTAK11Fx cabinets). It will not work in slots 4
through 10 in these cabinets.
NTAK20 provides 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
Clocking modes
The clock controller can operate in one of two modes: tracking or non-
tracking (also known as free-run).
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
Option11C cabinet. A cabinet that has a digital trunk must have a
clock controller.