Nortel Circuit Card Installation Manual page 571

Card interfaces
The NT8D14 Universal Trunk card passes voice and signaling data over
DS-30X loops, and maintenance data over the card LAN link. These
interfaces are described in "Intelligent Peripheral Equipment" on
Trunk interface units
The NT8D14 Universal Trunk card contains eight identical and
independently configurable trunk interface units (also referred to as circuits).
Each unit provides impedance matching and a balanced network in a signal
transformer/analog hybrid circuit.
Also provided are relays for placing outgoing call signaling onto the trunk.
Signal detection circuits monitor incoming call signaling. Two codecs are
provided for performing A/D and D/A conversion of trunk analog voiceband
signals to digital PCM signals. Each codec supports four trunk interface units.
The following features are common to all units on the card:
• trunk type configurable on a per unit basis
• terminating impedance (600 or 900 ohms) selectable on a per-unit basis
(minimum vintage BA)
• balance impedance (600 or 900 ohms or complex impedance network)
selectable on a per-unit basis (minimum vintage BA)
• control signals provided for RAN and paging equipment
• loopback of PCM signals received from trunk facility over DS-30X
network loop for diagnostic purposes
• switchable pads for transmission loss control
NT8D14 Universal Trunk card
Circuit Card
Page 571 of 906
page
Description and Installation
32.