Circuit Pack Descriptions
7-78 Issue 8.0 July 2002
Power Circuitry 7
The OC12 (1.3 STD) circuit pack receives two sources of −48 volts that are diode
OR'd, fused, and filtered. A modular DC-to-DC power converter produces +5 volts
used on the circuit pack.
If the OC12 (1.3 STD) circuit pack detects the failure of the onboard fuse or power
converter the red FAULT LED will light. If the fuse or power converter fails, the
LNCTL circuit pack provides +5 volts to light the FAULT LED on the OC12 (1.3
STD) circuit pack.
Quick Reference Summary 7
Transmit Functions 7
The OC12 (1.3 STD) circuit pack performs the following transmit functions:
a. Receives one OC-12 (622.08 Mb/s) non-return-to-zero (NRZ) SONET
compatible optical signal from a lightguide cross-connect panel (or
equivalent)
b. Converts the optical OC-12 signal to an electrical STS-12/12c signal
c. Recovers a 622.08 MHz clock signal from STS-12/12c signal and retimes
the STS-12/12c signal with the recovered clock
d. Descrambles and demultiplexes the STS-12/12c signal into four STS-3
signals (155.52 Mb/s)
e. Scrambles and multiplexes the four STS-3 signals into four STS-3/3c
signals (each at 155.52 Mb/s)
f. Provides four STS-3 signals to an OC48 TRMTR circuit pack (s)
g. Accepts the OC-12 SONET section DCC bytes from the TOHCTL circuit
pack.
Receive Functions 7
The OC12 (1.3 STD) circuit pack performs the following receive functions:
a. Receives four STS-3 signals (each at 155.52 Mb/s) from an OC48 RCVR
circuit pack(s)
b. Recovers a clock signal from one of the STS-3 signals and retimes the
STS-3/3c signal with the recovered clock
c. Performs frequency adjustments and pointer processing on the four STS-3
signals
d. Scrambles and multiplexes the four STS-3 signals to an STS-12/12c signal
(622.08 Mb/s)
e. Converts the electrical STS-12/12c signal to an optical OC-12 signal
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