363-206-295
Circuit Pack Descriptions
Issue 1
December 1997
7-71
General Description of Operation
7
The 23H/23H-U OLIU circuit pack provides an interface between an OC-12 optical
line and 12 STS-1 signals and can be used in ring applications. The 23H/23H-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 23H/
23H-U OLIU then performs an electrical-to-optical conversion and outputs an
OC-12 optical signal for transmission on an optical fiber.
The 23H/23H-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 23H/23H-U OLIU
outputs 24 STS-1 signals, 12 to service and 12 to protection TSI circuit packs.
The 23H/23H-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 23H/23H-U OLIU receives its timing signals from the TSI circuit packs.
Fiber access is via a pair of
ST (23H) or universal (23H-U) lightguide cable
connectors from the 23H/23H-U OLIU faceplate. Single-mode fiber is suggested
for optimum performance. The 23H/23H-U OLIU photonics meets SONET long
reach specifications. The 23H/23H-U is not hardened for uncontrolled
environments and is used in CO applications.
For 23H 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 loopback
testing requiring 19 dB attenuation, use the 4C Test Cable. For 23H-U
applications, see Section 10, "Technical Specifications," for a list of universal
buildout attenuators.
