Nortel Networks NN43001-301 - Manual (Page 156)

156 Clock Controller description and installation
Introduction
This chapter introduces the NTRB53 Clock Controller, and provides
procedures on how to install this clock controller on Large Systems.
The NTRB53 Clock Controller replaces the QPC471H and QPC775F in
new systems. QPC471H and QPC775F Clock Controllers continue to be
supported.
Note: The NTRB53 Clock Controller cannot be combined with a
QPC775 or a QPC471 card in one system
The illustrations used in the description section depict a Small System.
However, the system can also be representative of a Large System.
Description
This section provides an overview on the use of clock controllers. For Large
Systems, the following clock controllers are supported:
• NTRB53
• QPC471
• QPC775
Note: Clock controllers cannot be mixed in one system.
The NTRB53 Clock Controller is available for all markets. The QPC471
Clock Controller is available for U.S. markets. Vintages A through G of the
QPC471 Clock Controller can be used in one system; vintage H of QPC471
Clock Controllers cannot be mixed with clock controllers of other vintages.
The QPC775E Clock Controller card is available for only Canadian and
International markets.
Need for synchronization
Digital trunking requires synchronized clocking so that a shift in one clock
source will result in an equivalent shift of the same size and direction in all
parts of the network.
When digital signals are being transported over a communication link,
the receiving end must operate at the same frequency (data rate) as
the originating end to prevent loss of information. This is referred to
as link synchronization. If both ends of a communication link are not
in synchronization, data bit slips occur and therefore a loss of data
results. In general, accurate timing is very important, but more importantly
synchronized timing is a must for reliable data transfer.
Nortel Communication Server 1000
ISDN Primary Rate Interface Installation and Commissioning
NN43001-301 02.03 Standard
Release 5.5 7 December 2007
Copyright © 2003-2007, Nortel Networks
.