Nortel Networks 1000 - Manual (Page 374)

374 NT6D70 SILC Line card
The clock converter converts the 5.12 MHz clock from the IPE backplane
into a 2.56 MHz clock to time the IPE bus channels and an 8 kHz clock to
provide PCM framing bits.
The PE interface logic consists of a Card-LAN interface, a PE bus
interface, a maintenance signaling channel interface, a digital pad, and a
clock controller and converter.
The Card-LAN interface is used for routine card maintenance, which
includes polling the line cards to find the card slot where the SILC is
installed. It also queries the status and identification of the card and
reports the configuration data and firmware version of the card.
The PE bus interface connects one PE bus loop that has 32 channels
operating at 64 kbps and one additional validation and signaling bit.
The Maintenance Signaling Channel (MSC) interface communicates
signaling and card identification information from the CS 1000CPU to
the SILC MCU. The signaling information also contains maintenance
instructions.
The digital pad provides gain or attenuation values to condition the level of
the digitized transmission signal according to the network loss plan. This
sets transmission levels for the B-channel voice calls.
The clock recovery circuit recovers the clock from the local exchange.
The clock converter converts the 5.12-MHz clock from the PE backplane
into a 2.56-MHz clock to time the PE bus channels and an 8-kHz clock to
provide PCM framing bits.
S/T interface logic
The S/T interface logic consists of a transceiver circuit and the DSL power
source. This interface supports DSLs of different distances and different
numbers and types of terminal.
The transceiver circuits provide four-wire full-duplex S/T bus interface.
This bus supports multiple physical terminations on one DSL where each
physical termination supports multiple logical B-channel and D-channel
ISDN BRI terminals. Idle circuit-switched B-channels can be allocated
for voice or data transmission to terminals making calls on a DSL. When
those terminals become idle, the channels are automatically made
available to other terminals making calls on the same DSL.
The power on the DSL comes from the SILC, which accepts –48 V
from the IPE backplane and provides two watts of power to physical
terminations on each DSL. It provides -48 V for ANSI-compliant ISDN
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
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