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Circuit Pack Descriptions
Issue 1 December 1997 7-65
General Description of Operation 7
The 23G/23G-U OLIU circuit pack provides an interface between an OC-12
optical line and 12 STS-1 signals. The 23G/23G-U OLIU provides 24 STS-1 input
ports, 12 from service and 12 from protection TSI circuit packs. It selects up to 12
STS-1 inputs, performs pointer processing and frame alignment on each STS-1,
inserts transport overhead, and combines and scrambles the 12 STS-1 signals
into an STS-12 (622.08 Mb/s) signal. The 23G/23G-U OLIU then performs an
electrical-to-optical conversion and outputs an OC-12 optical signal for
transmission on an optical fiber.
The 23G/23G-U OLIU receives an optical OC-12 signal and converts it to an
electrical signal. It frames on and descrambles the signal, processes the transport
overhead, and demultiplexes the STS-12 into 12 STS-1 signals. It performs
pointer processing and frame alignment on each STS-1. The 23G/23G-U OLIU
outputs 24 STS-1 signals, 12 to service and 12 to protection TSI circuit packs.
The 23G/23G-U OLIU performs maintenance and provisioning functions
associated with the STS-1 and OC-12 inputs and outputs. It provides access to
the line and section overhead in the STS-12 signal and interfaces to the TSI circuit
pack at the STS-1 rate and to the optical line at the OC-12 rate. It interfaces to the
SYSCTL and OHCTL and sends recovered timing signals to the TGS circuit
packs. The 23G/23G-U OLIU receives its timing signals from the TSI circuit packs.
Fiber access is via a pair of
ST
(23G) or universal (23G-U) lightguide cable
connectors from the 23G/23G-U OLIU faceplate. Single-mode fiber is suggested
for optimum performance. The 23G/23G-U OLIU photonics comply with SONET
long-reach specifications.
For 23G applications requiring external optical attenuators, the faceplate-mounted
transmit (OUT) connector is designed to accept a lightguide buildout. Available
buildouts are A3010B - 5 dB, A3010D - 10 dB, and A3010F - 15 dB. For 23G-U
applications, see Section 10, "Technical Specifications," for a list of universal
buildout attenuators.
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