Timing Options
Timing Option Descriptions
076R155-000
SpectraComm 553 Fractional T1 DSU
D-9
Issue 7
Installation and Operation Manual
Station Timing
When the SC553 is optioned for station timing, it times data at its DS-1 network interface by means
of a 1.544 Mbps timing signal supplied from the Telco central office on a separate circuit. The
station clock signal is input to the SC553 at the lower RJ48 jack located at the rear of the
SpectraComm/UAS shelf on Zone1.(Refer to Chapter 2, Installation and Setup ). The timing
signals are transferred through that jack using a standard EIA RS-422 interface. See
.
Figure D-6
Station Timing
SC553 CSU/DSU
Lower RJ48 jack
at Zone 1
SpectraComm/UAS Shelf
S
h
el
f B
a
ck
p
lan
e
Cascade Equipment
Station
Clock
Interface
Network Transmit Timing Source
Station
Shelf
Cascade
Internal
Receive
Transmit
Interface
to
Backplane
Data
Highways
Cascade
Interface
Network
Interface
