Circuit Pack Descriptions
7-102 Issue 8.0 July 2002
The pointer processor performs phase, frequency, and frame realignment. The
input data is descrambled and fed into an elastic store that accommodates input
signal phase and wander. Frequency alignment is accomplished by using pointer
adjustments (byte stuffs). New overhead frames are generated with respect to the
local frame synchronization, and new pointer values are inserted into the outgoing
overhead. After pointer processing, the 155.52 Mb/s signals are
frame-synchronized and phase-aligned to the local system clock. The 739B2,
739B4, 739C2, 739J2, 739J3, 739J4, 739R2, and 739S2 OC48 TRMTR A/D
circuit packs then pass the 155.52 Mb/s signals to the transmit byte processor.
The 739B5, 739C5, 739E[1-16], 739G[1-8], 739H[1-16], 739J5, 739P5, 739R5,
and 739S5 OC48 TRMTR A/D circuit packs pass the 155.52 Mb/s signals to the
STS-1 time slot assignment (TSA) device.
The STS-1 TSA device in the 739B5, 739C5, 739E[1-16], 739G[1-8], 739H[1-16],
739J5, 739P5, 739R5, and 739S5 OC48 TRMTR A/D circuit packs demultiplexes
the 155.52 Mb/s (STS-3) signals to 96 STS-1 signals. Forty-eight STS-1 signals
can be cross-connected to output time slots in the OC-48 signals. The STS-1
cross-connections are based on the connection matrix loaded into the STS-1 TSA
device by the board controller. The STS-1 switch fabric provisioning is fully data
hitless and 100 percent non-blocking. This allows any input STS-1 signal to be
placed in any position in the byte interleaved OC-48 line signal. The STS-1 TSA
device multiplexes the 48 STS-1 signals to sixteen STS-3 (155.52 Mb/s) signals
and sends them to the transmit byte processor.
The transmit byte processor combines the pointer and payload information from
the 155.52 Mb/s signals with internally and externally generated SONET transport
overhead to form a parallel scrambled format. The optional Overhead Controller -
Terminal [OHCTL (TERM)] circuit pack provides the externally generated SONET
transport overhead bytes. The 155.52 Mb/s signals are then passed to the
multiplexer circuit.
The multiplexer circuit byte interleaves the 155.52 Mb/s signals into a single 2.488
Gb/s STS-48 serial data stream and passes it to the electrical-to-optical module.
The electrical-to-optical module converts the STS-48 signal to an optical OC-48
signal. A single line distributed feedback laser with driver and control circuits
converts the electrical signal to optical pulses for transmission.
Fiber access to the OC48 TRMTR A/D circuit pack is via a fixed
ST
-type buildout
block and a removable
ST
-type, FC/PC-type, or SC-type lightguide buildout on the
circuit pack faceplate. Lightguide buildouts are chosen based on the type of
connector interface the single-mode lightguide jumper is equipped with. There are
three types of lightguide buildouts available for OC48 TRMTR A/D circuit packs:
ST
-type, FC/PC-type, and SC-type. All factory-equipped OC48 TRMTR A/D circuit
packs come with a removable
ST
-type 0-dB lightguide buildout. When installing or
removing lightguide buildouts, do not pull the beam (front tab) outward. Pulling the
beam (front tab) outward could result in breaking the beam (front tab).
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