NEC NEAX 2000 Programming Manual page 217

PLO
The PLO (Phase Locked Oscillator) equipped on the MP card is responsible to synchronize the
system to the digital network clock.
When the PBX is a clock receiver office, the PLO generates the clock signals according to the
source clock received from the source office within the network. The source clock signals are ex-
tracted at DTI cards and supplied to the PLO. Two clock routes are available; one is the route 0
from the source office, and the other is a standby route 1 from a sub-source office. When no clock
signals arrive from the source and sub-source office, due to a transmission line failure, the PLO
keeps generating the clock signals at the frequency of the previous source clock. The PLO can
receive different frequency of source clocks from the route 0 and route 1.
Figure below shows an example of clock supply route when the system is a receiver office.
SOURCE OFFICE
TDSW
SOURCE
CLOCK
~
PLO
DTI 0 and DTI 1 must be mounted in PIM0.
NOTE:
Clock Supply Route
SUB-SOURCE OFFICE
DTI DTI
DTI
RECEIVER OFFICE
DTI
– 197 –
DIRECT DIGITAL INTERFACE (DDI)
RECEIVER/LOCAL-RECEIVER OFFICE
TDSW
DTI
DTI
PLO
TDSW
DTI
DTI
PLO
TDSW
DTI 0
DTI 1
PLO
PBX
NOTE
: DIRECTION OF CLOCK
SIGNAL SUPPLY
PLO
A2195-10