Clocking Modes - Meridian Nortel 1 Option 11C Technical Reference Manual

Page 504 of 544

Clocking modes

553-3011-100 Standard 14.00
NTAK20 clock controller
• NTBK22 MISP card (page 261)
• NTRB21 DTI/PRI/DCH TMDI card (page 461)
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.
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.
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
The clock controller can operate in one of two modes: tracking or non-
tracking (also known as free-run).
January 2002
IMPORTANT