363-206-295
Circuit Pack Descriptions
7-68 Issue 1 December 1997
Timing Circuitry 7
Each TGS circuit pack sends timing signals to the 23G/23G-U OLIU circuit pack
via the TSI circuit packs.
The 23G/23G-U OLIU circuit pack sends a clock signal to both TGS circuit packs
for loop timing.
Protection Circuitry 7
The 23G/23G-U OLIU provides STS-1 data path selectors for implementing a 1x1
protection switch between TSI circuit packs. The selectors are controlled by the
SYSCTL.
The 23G/23G-U OLIU is protection switched by the SYSCTL in response to fault
indications on the 23G/23G-U OLIU, or in response to fault indications on a
transmission circuit pack with which it interfaces, or in response to external
commands.
Fault Detection Circuitry 7
The 23G/23G-U OLIU circuit pack has in-service and out-of-service built-in test
capability. In-service device testing is continuous, and errors are reported to the
SYSCTL when they occur via the intra-shelf control bus. Incoming and outgoing
optical power thresholds are also monitored.
There is no electrical loopback in the 23G/23G-U OLIU. All loopbacks are external
optical loopbacks which require an attenuator.
Performance Monitoring 7
The 23G/23G-U OLIU provides PM circuitry for the following maintenance
parameters:
■ Parity error counts
■ Incoming OC-12 OOF counts
■ Outgoing OC-12 laser bias current threshold
■ Line parameters based on B2 coding violations.
Power Circuitry 7
The 23G/23G-U OLIU circuit pack uses board-mounted DC-DC power converters
that converts −48 V received from the backplane to +5 V, −5.2 V, +15 V, and −2.3
V for use on the circuit pack. The 23G/23G-U OLIU interfaces with both the A and
B feeders and provides a "diode-ORed" so that loss of one feeder will not affect
the 23G/23G-U OLIU. A fuse element is provided at the −48 V input to the DC-DC
converter.
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