363-206-295
Circuit Pack Descriptions
7-74 Issue 1 December 1997
Timing Circuitry 7
Each TGS circuit pack sends timing signals to the 23H/23H-U OLIU circuit pack
via the TSI circuit packs.
The 23H/23H-U OLIU circuit pack sends a clock signal to both TGS circuit packs
for loop timing.
Protection Circuitry 7
The 23H/23H-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 23H/23H-U OLIU is protection switched by the SYSCTL in response to fault
indications on the 23H/23H-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 23H/23H-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 23H/23H-U OLIU. All loopbacks are external
optical loopbacks which require an attenuator.
Performance Monitoring 7
The 23H/23H-U OLIU provides PM circuitry for the following maintenance
parameters:
â– Parity error counts
â– Incoming OC-12 OOF
â– Outgoing OC-12 laser bias current threshold
â– Line parameters based on B2 coding violations.
Power Circuitry 7
The 23H/23H-U OLIU circuit pack uses board-mounted DC-DC power converters
that convert −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 23H/23H-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
23H/23H-U OLIU. A fuse element is provided at the −48 V input to the DC-DC
converter.
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