Circuit Pack Descriptions
7-24 Issue 8.0 July 2002
In the receive direction, the receive byte processor (RBP) on the OC48 Receiver
(OC48 RCVR) circuit pack transmits the overhead bytes via the overhead channel
to the overhead byte interface. The overhead byte interface then demultiplexes
the DCC and overhead bytes and makes them available for use.
Table 7-2 shows the DCC and overhead bytes that are provided by the OHCTL
(TERM) circuit pack.
* Not available at FT-2000 OC-48 Add/Drop-Rings Terminal when there is an
FT-2000 OC-48 Repeater Bay in the high speed line.
† Reserved for use in a future release.
Power Circuitry 7
The OHCTL (TERM) 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.
The OHCTL (TERM) circuit pack monitors the two −48 volt sources to the circuit
pack. If the OHCTL (TERM) circuit pack detects a failure of the onboard fuse or
power converter, the red FAULT LED will light. If the fuse or power converter fails,
the SYSCTL circuit pack provides +5 volts to light the FAULT LED on the OHCTL
(TERM) circuit pack.
Table 7-2. Overhead Bytes
Name OverheadByte Data Rate Access
Orderwire* E1 64 kb/s Interconnection Panel
Orderwire E2 64 kb/s Interconnection Panel
Growth† Z1-Z2 1.536 Mb/s Interconnection Panel
User† F1 64 kb/s Interconnection Panel
DCC D1-D3 192 kb/s System Controller
DCC D4-D12 576 kb/s System Controller
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