Section 360-880-202
7
4.
CIRCUIT DESCRIPTION
4.1
Normal (Drop and Re-Insert) Mode Configuration
The T1-S provides the centralized control, multiplexing and test features for the 360-80 ICB. T1 signals from and
to the WEST (primary T1) direction are first routed through the ST1U to the T1-S. The ST1U uses timing from the
T1-S and must be loop timed to the WEST to operate correctly.
T1 signals from and to the EAST (secondary T1) direction are routed to the ST1U. The ST1U includes a monitor
jack access to the T1.
The ST1U provides a bypass relay path for the T1 facility as part of the assembly, as shown in Figure 8. When
de-energized, these relays bypass the ICB and connect the WEST (primary) T1 to the EAST (secondary) T1.
When the ST1U and T1-S are installed and functioning properly, these relays are energized. Figure 8 shows the
relay contacts in this mode. If either of these modules fail or the T1-S is removed, the relay will release and by-
pass the T1. The ST1U can also be manually selected to bypass the T1.
The ST1U provides various front panel indicators to monitor operation .
X
M
T
R
C
V
MON
WEST
PROTECTION
BYPASS
CONTROL
X
X
X
X
X
X
X
X
EAST
TIMING &
FRAMING
TIMESLOT
CONTROL
CABLE
TO
T1-S
VOICE & DATA CIRCUITS
T1 (J6)
PRIMARY
During normal operation bypass,
relay is energized as shown.
EAST
T1 (J4)
SECONDARY
(J5)
T1-S
T1-S
BYPASS
CIRCUIT
Figure 8. Secondary T1 Unit Block Diagram
