Nortel Networks Circuit Card 사용자 설명서

 NTAK20 Clock Controller daughterboard

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.

The NTAK20 clock controller card can support 1.5 Mb, 2.0 Mb, and 2.56 Mb 
clock recovery rates.

Note: Clocking slips can occur between MG 1000S systems that are 
clocked from different COs, if the COs are not synchronized. The slips 
can degrade voice quality.

The clock controller circuitry synchronizes the system to an external 
reference clock and generates and distributes the clock to the system. The 
system 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:

•

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

Each MG 1000S that has a digital trunk must have a clock controller 
clocked to an external reference clock.

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 
cabinet.