DIRECT DIGITAL INTERFACE (DDI)
PLO
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A2195-10
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.
Clock Supply Route
NOTE: DTI 0 and DTI 1 must be mounted in PIM0.
PLO
TDSW
SOURCE OFFICE
~
SOURCE
CLOCK
RECEIVER/LOCAL-RECEIVER OFFICE
PBX
DTI
DTI
TDSW
RECEIVER OFFICE
DTI
DTI
DTI
TDSW
SUB-SOURCE OFFICE
PLO
DTI
DTI 1
DTI 0DTI
DTI
PLO
PLO
: DIRECTION OF CLOCK
SIGNAL SUPPLY
TDSW
NOTE
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