Nortel Circuit Card Installation Manual page 743

backplane line. It designates the DTI/PRI motherboard as a primary reference
source. The secondary reference is obtained from another DTI/PRI card,
which is designated by a technician. No other clock sources are used.
External timing interface
The clock controller provides an external timing interface and accepts two
signals as timing references. An external reference is an auxiliary timing
clock which is bridged from a traffic carrying signal and is not intended to be
a dedicated non-traffic-bearing timing signal. The clock controller uses either
the external/auxiliary references or the DTI/PRI references.
Hardware integrity and regulatory environment
The clock controller complies with the following hardware integrity and
regulatory specifications:
Item
EMI
ESD
Temperature
Humidity
Vibration/Shock
NTAK20 Clock Controller daughterboard
Specification
FCC part 15 sub- part J
CSA C108.8
CISPR publication 22
IEC 801-2
IEC 68-2-1
IEC 68-2-2
IEC 68-2-14
IEC 68-2-3
IEC 68-2-6
IEC 68-2-7
IEC 68-2-29
IEC 68-2-31
IEC 68-2-32
Circuit Card
Page 743 of 906
Description and Installation