Nortel Networks 1000 - Manual (Page 848)

848 NTAK79 2.0 Mb PRI card
If the incoming reference is unstable, the internal clock controller remains
continuously in the tracking stage with the LED flashing green all the
time. This condition does not present a problem, rather, it shows that the
clock controller is continually attempting to lock onto the signal. If slips
are occurring, however, it means that there is a problem with the clock
controller or the incoming line.
Free-run (non-tracking) In free-run mode, the clock controller does not
synchronize on any source, it provides its own internal clock to the system.
This mode can be used when the Option 11C is used as a master clock
source for other systems in the network. Free-run mode is undesirable if
the Option 11C is intended to be a slave. It can occur, however, when both
the primary and secondary clock sources are lost due to hardware faults
or when invoked by using software commands.
Clock controller functions and features
The NTAK79 clock controller functions and features include:
• phase lock to a reference, generate the 10.24 MHz system clock, and
distribute it to the CPU through the backplane. Up to two references at
a time are accepted
• primary to secondary switchover (auto-recovery is provided)
• prevent chatter
•
error burst detection and correction, holdover, and free running
capabilities
•
compliance with 2.0Mb CCITT specifications
• software communication
•
jitter filtering
•
use of an algorithm to detect crystal aging and to qualify clocking
information
The NTAK79 clock controller functions and features include:
• phase lock to a reference, generate the 10.24 Mhz system clock, and
distribute it to the CPU through the backplane. Up to two references at
a time may be accepted.
• provide primary to secondary switchover (auto-recovery is provided)
•
prevent chatter
•
provide error burst detection and correction, holdover, and free running
capabilities
• comply with 2.0Mb CCITT specifications
• communicate with software
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
.