Nortel Circuit Card Installation Manual page 838

Page 838 of 906
553-3001-211 Standard 3.00
NTRB21 DTI/PRI/DCH TMDI card
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
Option 11C cabinet. A cabinet that has a digital trunk must have a clock
controller.
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.
Clock rate converter
The 1.5 Mb clock is generated by a Phase-Locked Loop (PLL). The PLL
synchronizes the 1.5 Mb DS1 clock to the 2.56 Mb system clock through the
common multiple of 8 kHz by using the main frame synchronization signal.
August 2005
IMPORTANT!